The Po Delta Lagoons by the Consorzio Di Bonifica Delta Del Po October - 2013

THE PO DELTA LAGOONS BY THE CONSORZIO DI BONIFICA DELTA DEL PO OCTOBER - 2013

THE PO DELTA AND THE HYDRAULIC EFFICIENCY OF ITS DISTRIBUTARIES AND OUTLETS: THE STATE OF THE ART OF STUDIES AND KNOWLEDGE

MONITORING THE WATER QUALITY IN THE PO DELTA LAGOONS: ANALYSIS OF CHEMICAL-PHYSICAL PARAMETERS MEASURED BETWEEN 2005 AND 2010

SHELLFISHING IN THE PO DELTA LAGOONS, VENETO: SOCIO–ECONOMIC ASPECTS

ELEMENTS OF ENVIRONMENTAL ENGINEERING IN THE STABILIZATION OF THE SACCA SCARDOVARI THE PO DELTA LAGOONS

OCTOBER - 2013 1

THE PO DELTA LAGOONS BY THE CONSORZIO DI BONIFICA DELTA DEL PO

2 PREFACE Presentation by Maurizio Conte (Veneto Region)

3 MANAGEMENT AND STUDYING OF THE PO DELTA by Fabrizio Ferro (Consorzio di Boniﬁca Delta del Po)

4 THE PO DELTA AND THE HYDRAULIC EFFICIENCY OF ITS DISTRIBUTARIES Studies & Research AND OUTLETS: THE STATE OF THE ART OF STUDIES AND KNOWLEDGE by Marco Zasso and Italo Saccardo (ARPAV Belluno), Giancarlo Mantovani (Consorzio di Boniﬁca Delta del Po), Bruno Matticchio (IPROS Padova), Alberto Agnetti and Silvano Pecora (ARPAEM Parma), Tommaso Settin (ARPAV Belluno, AIPO Rovigo)

22 MONITORING THE WATER QUALITY IN THE PO DELTA LAGOONS: ANALYSIS OF CHEMICAL-PHYSICAL PARAMETERS MEASURED BETWEEN 2005 AND 2010 by Pietro Traverso and Angelo Rubino (Università Ca’ Foscari di Venezia), Davide Zanchettin (Max Planck Institute for Meteorology)

40 SHELLFISHING IN THE PO DELTA LAGOONS, VENETO: SOCIO–ECONOMIC ASPECTS by Francesco Donati (Professor of Agricultural Policies and Economics) and Elena Fabbro (Università di Udine)

58 ELEMENTS OF ENVIRONMENTAL ENGINEERING IN THE STABILIZATION OF THE SACCA SCARDOVARI by Andrea Bonometto (Environmental Engineer), Lorenzo Bonometto (Società Veneziana di Scienze Naturali), Pippo Gianoni (Iuav Venezia and Dionea Sa Locarno)

84 THE FAO-IMOLA PROJECT Various Activities by Lino Tosini (Fondazione Ca’ Vendramin), Massimo Sarti (Chief Technical Adviser for the IMOLA project), Bruno Matticchio (IPROS Padova)

88 DELTAMED ASSOCIATION ACTIVITIES 2011-2012 by Lino Tosini (Fondazione Ca’ Vendramin)

90 ON THE TIDALLY AVERAGED DIFFUSION IN THE VALLONA LAGOON (PO Thesis Review RIVER DELTA) Andrea Deﬁna (Università degli Studi di Padova), Graduate Alice Sgarabottolo

92 SALTWATER INTRUSION IN THE PO DELTA: PROBLEM OR OPPORTUNITY FOR THE TERRITORY? ADAPTATION PROPOSALS FOR AN INTERREGIONAL AREA Pippo Gianoni (Iuav Venezia), Graduate Stefania Girardi

1 The Po Delta Lagoons October 2013

PREFACE

MAURIZIO CONTE The common element that characterizes the territory of the Po Delta, more so than Veneto Region Enviromental Counselor any other area, is its richness in surface water, an element that is large enough and important enough for it to be called a “place.” A place that is present both in the cultivated lands of the valleys, as well as the coastal lagoons, and that is made up of the scope that is the relationship between land and water. In its extensive ﬁelds, this scope of the relationship between land and water is present where the channels and ditches border the patches of land that make up farms at rhythmic intervals, while in the valleys and lagoons it is present along the thin strips of land bordering the stretches of water in valleys or those separating the lagoons from the sea.

Those who have worked in the Po Delta environment for a long time know that, what- ever the field, the most delicate point of a hydraulic intervention and/ or vivification is the point where the land meets the water, one conditioning the other, in fact in the Delta one intervenes on the land in order to have an effect on the water and on the water in order to modify the land. It is in this close relationship between the irrigation water and the agricultural land that the fertility of the arable land in the Delta is expressed; likewise the success of delta mussel fishing is due to the link between salt & brackish water and the lagoon bottoms.

The future also holds another equally important meeting point for the Po Delta area. A place of intangible relationships, where management and maintenance choices regarding the Delta area should be shared and, more importantly, guidelines should be identified for managing the effects that productive activities and climate change in the large hydraulic basin of the Po will have upon this delicate environment in the coming years. This new meeting point, which has its origins in the community system as implemented by national legislation, as expressed in the Contract of the mouths, which enables “those who govern, use and live off the water of the rivers, the lesser hydrographic network, the valleys, lagoons and sea, to achieve the goal of setting up local projects that are shared and verified in their environmental, economic and financial feasibility.”

As far back as the late 1980s, the Veneto delta was recognized as a laboratory for interventions in the lagoon areas, for which a special Interdisciplinary Commission was established in order to address the many planning and monitoring activities and the carrying out of interventions, whilst acknowledging that this is a difﬁcult territory, one that is prone to unpredictable transformations and adaptations caused by storms and the ﬂooding of the Po.

With the passing of the Contract of the mouths for the Delta area, the original intervention implemented through the Interagency Committee will be replaced by the adoption of a system of shared rules for the integrated management, the exploitation of land, and water resources management. The Contract of the mouths Action Program will be used as a point of reference for all actions resulting from voluntary agreements and must meet environmental sustainability criteria. It is with great enthusiasm that one welcomes this new institution that, in institutional terms, reintroduces the importance relationships between different systems, on which nature frequently relies, allowing those who are lucky enough to spend time in the Veneto delta to appreciate the unique- ness, richness and beauty of this area.

2 THE MANAGEMENT AND STUDYING OF THE PO DELTA

FABRIZIO FERRO The Consorzio di Bonifica Delta del Po’s previous publication regarding the wet- Consorzio di Bonifica Delta del Po President lands were very well received due to the scientific content of the topics dealt with regarding above all, the monitoring activities and studies carried out in the Management of the Po Delta Lagoons for which the Consorzio di Bonifica Delta del Po has been responsible for over 25 years.

Despite the previous issues being print editions of excellent quality and design that were also easy to consult, the Comitato Tecnico Scientifico, which advises the Con- sorzio on lagoon viviﬁcation activities, suggested a new format, no longer printed but published online and downloadable from the Consorzio di Bonifica Delta del Po and the Fondazione Ca’ Vendramin websites, as well as the website specially created by the Consorzio in order to promote the Geographical Information System on the lagoons (http://sil.deltapo.it). The reason for this choice lies in the possibility of greater exposure for the product, reaching institutions, scholars, experts, and students who use the Web as an archive for information.

In this issue important studies carried out by the Consorzio are described with particular regard to the Sacca degli Scardovari, in which we look into issues concerning the adaptation of the mathematical model that simulates the hydrodynamics of the Sacca in order to assess the impact and effectiveness of interventions and planning, the analysis of the economic aspects associated with and resulting from the implementation of interventions, and a description of interventions carried out on the sandbar, aimed at their environmental restoration, with environmental engineering and the planting of pioneer species.

In lagoon areas that are sensitive to the ﬂow of the Po distributaries, with their mouths located only a few hundred meters from the lagoon mouths, it was necessary to identify the surrounding conditions and therefore the ﬂow discharged from each mouth, which is why distribution measurements were carried out in the Pontelago- scuro section on the various distributaries under the differing hydraulic conditions of the river.

Another issue relates to the synthesis of the results of years of monitoring the quality of the lagoon waters carried out in cooperation with ARPAV. This real-time monitoring is useful in predicting anoxia and eutrophication in the study of ingression phenomena in lagoons with an excess of freshwater and the monitoring of the lagoon’s “breathing”.

It is important to continue in efforts aimed at studying the Po Delta wetlands, a wonderful area from a naturalistic point of view and a source of income for the local people.

3 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the _STUDIES & RESEARCH art of studies and knowledge THE PO DELTA AND THE HYDRAULIC EFFICIENCY OF ITS DISTRIBUTARIES AND OUTLETS: THE STATE OF THE ART OF STUDIES AND KNOWLEDGE

MARCO ZASSO Introduction and salt water mixing processes and is Agenzia Regionale per la Prevenzione e therefore among the principal factors Protezione Ambientale del Veneto, Sicurezza per il Territorio Dept., Belluno The availability and the acquisition in the delicate balance of transitional of useful information for the hydrolog - aquatic ecosystems, that consequently ITALO SACCARDO Agenzia Regionale per la Prevenzione e ic characterization of the Po River Del- influence the numerous human activi- Protezione Ambientale del Veneto, Sicurezza ta plays a pivotal role in improving and ties (fishing, aquaculture, tourism) that per il Territorio Dept., Belluno integrating the cognitive framework revolve around these unique and highly GIANCARLO MANTOVANI of an extremely complex, and con- vulnerable areas. Therefore, it is exactly Consorzio di Bonifica Delta del Po, Taglio di Po stantly evolving system. In fact, there in such contexts that in-depth knowl- BRUNO MATTICCHIO are numerous factors involved in the edge brings significant implications to IPROS Ingegneria Ambientale, Padova evolution of the Delta plain, where the quality planning and designing of ALBERTO AGNETTI geo-morphological processes linked structural interventions, be they on the Agenzia Regionale per la Prevenzione to fluvial dynamics and factors related main branch of the Po, along the coast, e Protezione Ambientale dell’Emilia Romagna, Servizio Idro-Meteo-Clima, Parma to subsidence, tidal regimes and wave or within the lagoon. action, as well as structural interven - SILVANO PECORA Agenzia Regionale per la Prevenzione tions and related works carried out In order to update and broaden the e Protezione Ambientale dell’Emilia Romagna, over the years by the institutions in base knowledge of the phenomena Servizio Idro-Meteo-Clima, Parma charge of maintaining its watercourse that govern the dynamics and behavior TOMMASO SETTIN are strongly interconnected. of the Po River in the terminal stretch Agenzia Regionale per la Prevenzione e which makes up the Delta, ARPA Vene- Protezione Ambientale del Veneto, Sicurezza per il Territorio Dept., Belluno; Adequate knowledge of the hydro- to, ARPA Emilia Romagna and Consor- Agenzia Interregionale per il fiume Po, Rovigo dynamic regime in the Po’s terminal zio di Bonifica Delta del Po have collabo- stretches under different hydrologic rated in the carrying out of hydrological conditions is certainly a basic element surveys consisting of the measurement in defining and designing structural in- of flow rates and sediment transport terventions in order to, on one hand, along the various distributaries that ensure the hydraulic safety of the sur- make up the Delta. This article, based rounding area, and on the other, to pre- on available data (as documented by dict and prevent the intrusion of salt Ufficio Idrografico del fiume PO, UIPO wedges along the river courses in low and ENEL as of the 1930s up to 1989) water regimes. It should also be noted and on new hydrological information that these studies are of particular im- acquired between 2002 and 2011, aims portance to the analysis of hydrody- to provide a contribution to the quanti- namic flow and coastal morphology in fication of the various Po Delta distribu- relation to the dynamics of inherently taries’ hydraulic efficiency through the fragile ecosystems such as the Po Delta evaluation of the distribution of river lagoons. The hydraulic efficiency of the discharges. individual distributaries, as well as the various outlets to the sea, is closely con- Measuring Campaigns nected to the way in which sediment is 2002–2011 transported along the river’s course, and its resulting distribution along the Recently conducted measuring coastal arch, and therefore plays an im- campaigns have enabled the updating portant role in the evolutionary dynam- of knowledge on flow rate distribution ics of the delta coast and lagoon inlets. in the various delta distributaries. The In fact, delta distributary sedimentation, Consorzio di Bonifica Delta del Po car- along with the tides, determines fresh ried out monitoring campaigns in Sep-

4 Flow measurement sections 2002-2011

Main areas 0 2,5 5 Km

Figure 1: overview of tember 2002 and November 2007. The campaigns. Two more campaigns were measurement section September 2002 campaign concerned carried out in 2010 (June and Novem - locations on the main distributaries of the Delta. the main distributaries of the Delta ber) that saw a productive collabo - and the Po di Pila sea outlets, while ration between ARPA Veneto, ARPA that of November 2007 also investi - Emilia Romagna and the Consorzio di gated the distribution of the Po di Tolle Bonifica Delta del Po. outlets. The average flow recorded at Pontelagoscuro in these monitoring The measurements looked into the activities was close to 2,300 m 3/s. A distribution phenomenon during the measuring campaign was carried out falling discharge phase, as explained in May 2007 with the participation of in more detail below, monitoring high ARPA Emilia-Romagna, ARPA Veneto, flow rates never previously measured. ARNI, the Provincia di Ferrara, the In conjunction with flow measure- Consorzio di Bonifica Delta del Po and ments, samples aimed at the quanti - the Consorzio I° Circondario Polesine fication of suspended sediment trans- di Ferrara regarding the measuring of port were also taken during the 2010 the Po river’s low water outflow ( Pon- campaigns. Finally, a survey involving telagoscuro average Q equal to 657 flow distribution of the Po Grande be- m3/s). Measurements taken over a tween Po di Goro and Po di Venezia tidal hemicycle (12 hours) made it pos- was carried out in November 2011 that sible to determine the average flow coincided with flooding, with a peak rate along the delta distributaries in flow rate of about 5,900 m 3/s at Pon- sections also monitored during other telagoscuro.

5 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

Figure 2a: ADCP sensor towed and 2011. Figure 1 also pinpoints the by boat used for river sections equipped with hydrom - conducting ﬂow rate measurements. eter stems or in which there are au - tomatic hydrometric stations. These stations are equipped with ultrasonic hydrometers that are part of the Re- gione Veneto real time network. Un- fortunately due to technical problems not all the hydrometers were functioning when measuring was carried out. In addition to the hydrometers in Fig - ure 1, hydrometric data from Polesella (RO), and Pontelagoscuro (FE) were available. As previously mentioned, the outflow rate for the latter section Figure 2b: view of hydrometric is available. The data from these sta - monitoring tions are useful as a reference for the installation (hydrometer stem flow rate in the upstream sections for ultrasonic hydrometer and ultrasonic the relative propagation times of hy - hydrometer) on the drometric variations along the river Po di Gnocca. course.

In order to measure the outflow, trimaran mounted Doppler flow meters were towed along a section as or - thogonally as possible to the direction of flow. In particular, for the measure - hydrometer stem ments carried out during the falling discharge phase (2010 and 2011), an ultrasonic ADCP sensor (Figure 2a & Figure 2b) equipped with four trans- This survey was conducted by ARPA of hydrometric disruptions along the ducers operating on two different fre- Veneto in collaboration with AIPO. various distributaries. In this way it quencies in order to determine verti - With the exception of that conducted was possible to get a snapshot of a cal speed, and a transducer dedicated in May 2007, all the monitoring cam - situation that resembled, as closely as to bathymetric measurement, was paigns were carried out in hydrologic possible, the conditions along the vari - used. conditions characterized by high wa- ous stretches. ter stages (average Q average at Pon- The equipment also had two RTK telagoscuro between 2,300 and 5,900 It should also be noted that the GPS receivers: a “base” on the shore m3/s). Under these circumstances the survey methodology is perfectly con- and a “rover” mounted on the trima - measurements were carried out by sistent with the operational methods ran in order to permit the location and instantaneously monitoring the flow adopted for past campaigns, to which geo-referencing of the equipment’s rate along the various distributaries the results are compared below. Fig - movements along the section of riv - while attempting to plan and execute ure 1 shows the sections in which erbed being investigated. This tech- the surveys in conditions that were as measurements of flow and sediment nological device eliminates the uncer- synchronous as possible, also in rela - transport were carried out in the vari - tainties in the estimation of speed and tion to the various propagation times ous Delta distributaries between 2002 bathymetry in moving riverbed condi -

6 Velocity magnitude (m/s) Depth (m) Depth Distance North (m) Distance

Lenght (m) Distance East (m) River Depth Top Q Depth Bottom Q Depth

Ship track Average 2000 m/s

Figure 3: ADCP tions. In the 2002 and 2007 studies, tributaries) are summarized in Table 1. measurements of the ADCP equipment used did not Values in italics are the net difference the S4-b (Po di Pila) section on utilize GPS technology. It should be while the last column shows the aver- 06/11/2010 between stressed that, given the low flow rates age daily flow at Pontelagoscuro as a 10:57 and 11:02: detected in these measuring cam - reference value of the specific hydro - showing the course (right) and speed paigns, the slower speeds reduce the logical regime during the monitoring. distribution graph effects of riverbed movement in the (left). bathymetry and speed estimation. The Similarly, Table 2 represents the Po flow measurements performed in vari- di Pila’s three outlets to the sea (Busa ous studies and distribution percent- di Scirocco, Tramontana and Busa Dritta ages in the various distributaries of or di Levante) as well as those of the Po the Delta (Po di Goro, Venezia, Gnocca, di Tolle (Busa di Bastimento, Storiona, Maistra, Tolle and Pila) in relation to and Bocca del Po di Tolle). The results the total flow (calculated from the sum of the analysis carried out on samples flow measured along individual dis- of available data in order to compare

Measurement Po di Goro Po di Venezia Po di Gnocca Po di Maistra Po di Tolle Po di Pila Po at date (S0) (S1) (S2) (S3) (S4) (S4b) Pontelagoscuro m3/s % m3/s % m3/s % m3/s % m3/s % m3/s % m3/s (average daily) 14 Sept 2002 542 23.5 1,782 76.5 338 14.7 77 3.3 390 16.9 954 40.5 2,300 30 May 2007 34 5.2 623 94.8 74 11.2 9 1.4 103 15.7 437 66.6 657 27 Nov 2007 282 11.6 2,140 88.4 387 15.9 102 4.2 492 20.3 1,158 47.8 2,422 22 June 2010 668 13.8 4,093 84.4 743 15.3 208 4.3 1,037 21.4 2,193 45.2 4,936 6 Nov 2010 655 13.6 4,139 86.3 789 16.45 215 4.5 993 20.7 2,141 44.7 5,102 11 Nov 2011* 748 13.5 4,785 86.5 ------5,803

Table 1: flow measurements carried out along the various distributaries and flow percentages for each section compared to total flow calculated from the sum of flow measured along the various branches (Goro, Gnocca, Maistra, Tolle, Pila) (italics represent the net difference). *The measurements were taken at Serravalle, monitoring the flow of the Po Grande, Po di Venezia and Po di Goro over a reduced time frame. The quantity of data acquired is confirmed by the small differences in percentage in terms of balance: the difference between the sum of the two distributaries (Goro and Venezia) and the flow rate measured on the Po Grande, again at Serravalle, is 1.1%.

7 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

Measurement Busa di Busa di Busa di Busa del Busa Bocca Po date Tramontana Levante Scirocco Bastimento Storiona di Tolle m3/s % m3/s % m3/s % m3/s % m3/s % m3/s %

14 Sept 2002 247 25.9 623 65.3 84 8.8 ------

27 Nov 2007 263 22.7 809 69.9 86 7.4 27 6.7 322 76.2 73 17.2 22 June 2010 671 31.1 1,215 56.2 275 12.5 ------6 Nov 2010 661 28.9 1,337 58.5 286 12.5 48 4.4 845 77.7 194 17.8

Table 2: flow measurements carried out along the Po’s various outlets to the sea. The Po di Pila percentages refer to total flow calculated from the sum of the individual measurements while the percentages for the mouths of the Po di Tolle refer to the Po di Tolle total flow at Scardovari (S4c) (italics represent the net difference).

the percentage of flow currently ab- The data available up to the end of sorbed by the individual distributar- the 1960s (UIPO and Canali) show the ies of the Delta with that of the past hydraulic efficiency of the Po di Goro can be seen below. Separate analysis to be very consistent and stable over was conducted on the Delta’s six main time (Figure 4). The few measurements distributaries (Po di Goro, Po Venezia, from 1970 to 1990 (source: ENEL) show Po di Maistra, Po di Tolle, Po di Gnocca an apparent change in the tributary’s and Po di Pila), the mouths of the Po di behavior pattern with an increase in ef- Pila (Busa Dritta, Busa di Tramontana ficiency in relation to low/ medium wa- and Busa di Scirocco) and on the three ter regimes. The only recent available mouths of the Po di Tolle (Busa del data (regarding “low stage” regimes) Bastimento, Busa Storiona and Bocca tends to strongly realign past behavior del Po di Tolle). patterns while showing a trend of increased efficiency for this distributary. Distribution of Flow along the This behavior pattern is even more Main Distributaries of the Delta pronounced in “high stage” regimes where the historical data tends to show For each main distributary, all avail- an asymptotic tendency in which, for able measurements are once again pro- high flow rates, the Po di Goro was able posed showing the flow percentage of to dispose of close to 10% of the total each distributary in relation to average runoff of the Po River. daily flow at Pontelagoscuro. In terms of quality, the distinction is made between However the recent 2010 and 2011 “low stage” (flow less than 1,000 m3/s at studies show the capacity of the dis- Pontelagoscuro), “medium water”(flow tributary to drain about 13-14% of the between 1,000 m3/s and 3,000 m3/s at total runoff of the Po River. This trend Pontelagoscuro) and “high stage” (flow was also evident in the Fiorotto study Figure 4: flow rate of more than 3,000 m3/s at Pontel- (2002) based on a physical model of in the various agoscuro), as proposed by Visentini and the Po di Venezia-Po di Goro hydrau- distributaries of the Po compared subsequently adopted for all analysis lic intersection node, which estimates to the average that followed. In Figure 4, for the vari- average efficiency percentages of flow of the Po at Pontelagoscuro ous distributaries of the Po Delta, data the Goro distributary that range from with respect to the relating to distribution percentage of 10.8% for incoming flow of 3,000 m 3/s total flow of the Po: comparison of flow are compared to the average value to values close to 14% for that of over the historical data estimated at Pontelagoscuro. 8,000 m3/s. available.

8 Low water Medium water High water

Low water Medium water High water

Measurements Measurements 2002-2001 2002-2001

Low water Medium water High water Low water Medium water High water

Measurements Measurements 2002-2001 2002-2001

Low water

Medium water High water Low water Medium water High water

Measurements Measurements 2002-2001 2002-2001

9 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

Figure 5: the evolutionary trend of the Po Finally one notes how, during the remained more or less constant for Grande highlights 2002 and 2007 campaigns relating the next twenty years (9.9% in 1958- a progressive weakening in to the “medium water” regime, this 1959), while today it boasts percent - efficiency to the branch of the Po was not subject to ages close to double those estimated advantage, in differing ways, of all the direct measurement. All this suggests at the beginning of the last century. lateral distributaries. that on the whole, in this distributary This behavior is opposite to that of of the Delta, there is an evolution - The hydraulic behavior of the Po the effect following ary trend that tends to increase in di Venezia (downstream from where the realization of importance in the overall outflow of the Goro distributary branches out) the significant systemization water to the sea from the Po River. is obviously a mirror image of the Po interventions carried The progressive trend of increasing di Goro’s behavior described above. out between the 1980s and today efficiency in the Goro distributary is Therefore, according to the data (straightening and also confirmed by the estimates made shown in Figure 4, there is an appar - widening of the bed). Right: Creation of by Canali in 1959, according to which ent decrease in the efficiency of that the new bed in the at the beginning of 1900 the flow rate distributary over all regimes investi - Corbola and Bottrighe coves. Left: Artificial percentage in that distributary in gated. On the other hand it should be straightening bar “high stage” regimes was 7%, which noted that, like the data provided by (drizzagno) realized later increased to 9.3% in the period ENEL between 1970 and 1990, there at the Volta Vaccari cove. between 1926 and 1939, after which it were profound differences with that

10 which had been monitored in the Regarding the Po di Gnocca, it is The Po di Maistra, of all the main past, even if such behavior was en - evident how the percentage of the distributaries, is certainly the least hanced by an “overestimation of flow portion of the outflow discharged significant in terms of the percentage in the Pontelagoscuro section, as ver- to the sea through this distributary of contributions to sea of the total ified in 1988-1989, when outflow rate maintains fairly stable in the face of outflow of the Po River. The Canali checks were carried out (by ENEL) in the Po’s significant flow rate vari - report (1959) emphasized that, based this section” (Grego, 1990). Regard- ations. On average this percentage on a period of a hundred years, it was ing the division between the Goro and amounts to values between 10 and evident how the mouths of the Po Venezia distributaries, one must em - 15%. Historical data also show that, oriented towards the Scirocco would, phasize the importance of extending over time, there has been an increase over time, become less active, as op - flow monitoring (in particular in the in efficiency in this class, a variation posed to those oriented toward the medium water hydrometric regime that came to the fore over a twenty- Bora quadrant. This phenomenon for which there is no recent available year period from 1939 to 1959, com - is common to all the rivers with sig - data), through simultaneous meas- pared to the preceding period, as re - nificant sediment transport with out - urements at the inlet to the two dis - ported by Canali (1959). In the years lets along the Padano-Veneto coast, tributaries, in order to minimize pos - that followed, and up to this day, which tend to divert their mouths in sible uncertainty due to propagation there have been no apparent signifi - the quadrant between N and E. The phenomena along the course of the cant changes in the efficiency of this main cause of this trend according to river. distributary. Cialdi (see Canali, 1959), are the pre -

11 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

vailing winds and sea induced currents, winds and subsequent wave induced elements that govern the accretion of currents.” Following interventions for sand near the mouth. the realization of the Polesine Camer- ini station, this distributary was more The Po di Maistra’s hydraulic behavior closely monitored by ENEL in the period pattern is quite clearly in line with this 1970-1990. Given the specific investiga- trend, as one notes from the data in Fig- tion aims, to look into the effects of the ure 4, how this distributary’s hydraulic intervention on the Po River in shallow efficiency has grown significantly over water conditions, monitoring focused the different monitoring periods. The mainly on “low and medium stage” re- recently performed “medium stage” and gimes. “high stage” measurements, although small, again suggest an increase in ef- In this context, there was a nota- ficiency of this distributary, when com- ble net increase in this distributary’s pared to the results of the last systemat- efficiency with values that were even ic measurements relating to the period slightly higher than those representing 1939-1959 (Canali). In such regimes, the the period 1926-1938 (18-20%) regard- flow rate percentage through the Po di ing “medium water” and well above Maistra would have been between three the 20% (some even as high as 25%) and four percent. Regarding the “low in “low stage”. This trend and similar water” regime, as in the case of the Po values were also confirmed by recent di Goro, the measurements carried out studies (even if a single value relating by ENEL (1970-1990) are contrary to the to “low stage” regime is not sufficient behavior patterns observed in the only to draw any definitive conclusion). How- recent campaign. In fact, the data from ever, regarding “high stage” regimes, May 2007 shows a very limited outflow it is evident how modern work means through that distributary. In this context have enabled the monitoring of a much the need for further instrumental stud- higher “range” of flow rates than in the ies in order to analyze these behavior past. Hence, past measurements that patterns, especially in “low stage”, is could be considered useful in making a clear. uniform comparison are not available for this “range”. However, for high flow The Po di Tolle distributary has rates, as the data in Figure 4 shows, it showed variable behavior patterns over is clear how the efficiency of this dis- time, in fact, for a period at the begin- tributary, in the falling discharge phase, ning of the last century (1926-1938), it is certainly superior to that of the past, was characterized by an outflow capac- resulting in about 20% of the total flow ity of close to 15% of the total, followed of the Po river being let out to sea. by a decrease in hydraulic efficiency in the 1939-1959 period. The Po di Pila distributary has progressively and significantly decreased in This variation had already been re- efficiency over the last century. ported by Canali (1959), thus confirm- Figure 6: historical Measurements. ing this evolutionary trend in the Delta From the data in Figure 4 one notes Anchored characterized by a “gradual decreasing how, in view of a substantial lack of be- measurement over time of the southern distributaries havior pattern variation recorded up to pontoon (above). Rod mounted reels as a result of, as previously mentioned, the end of the 1950s (even if, as reported (below). ENEL, 1973.

12 13 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

by Canali, signs of a certain reduction in (1990) highlighted how the reduction behavior patterns of this distributary, efficiency in “ medium water “ regimes of efficiency in the Pila distributary was but only suggests a possible evolution- were already evident), the following two actually amplified by the overestimation ary trend. On the other hand it is evident decades were characterized by a signifi- of flow at Pontelagoscuro, a phenome- how, over approximately 100 years, the cant drop across all regimes. It should non that came to light in checks carried efficiency of this distributary, being the be pointed out how, as of the 1970s, the out on the outflow rate in 1988-1989. main course for outflow to the sea, has intensive monitoring program in the Po The last two available measurements, decreased by more than 10% with peaks di Pila (UIPO 1970-1971 and ENEL 1970- especially regarding the “medium wa- close to 15% in “high stage” conditions. 1990) includes measurements that only ter”, regime suggest a possible further This behavior, as noted above, was off- focused on this distributary of the del- reduction in efficiency of this distribu- set by a progressive increase in hydrau- ta. As a result, the uncertainty regard- tary that seems however, to remain un- lic efficiency in all the other distributar- ing the outflow rate at Pontelagoscuro, changed compared to the two extreme ies. which provided the flow reference, has regimes of “low stage” and “high stage”. resulted in the propagation of uncer- It is also clear how the relative lack of A final consideration puts together tainties in the evaluation of the hydrau- available measurements does not per- data analysis relating to all distributar- lic efficiency in the Po di Pila. Grego mit the univocal definition of hydraulic ies up to now considered precise. In all the graphs proposed, there is a strong dispersion of the “low stage” regime data; such behavior patterns are con-

Figure 7a: nected to difficulties in systematically LOW water percentage of monitoring all the Po’s distributaries in average daily flow at Pontelagoscuro hydrometric conditions markedly domi- carried into the nated by the effect of the tide, under sea from the Busa di Tramontana. homogeneous conditions (over an en- Graphic comparison tire tidal cycle). Therefore, in such con- between the ditions, it is difficult to find a function measurements and the recent data that is able to univocally summarize the available. patterns, while it is certainly easier to assess an “average efficiency” in these MEDIUM water HIGH water distributaries.

Distribution in the Mouths to the Sea

The hydraulic efficiency of the Pila and Figure 7b: Tolle distributaries’ mouths to the sea percentage of flow has been investigated with less continu- carried by the Busa di Tramontana ity over the last century (Figure 7) com- compared to the pared to surveys conducted to estimate total flow of the Po di Pila. The results the flow rate distribution along the main of the comparison distributaries. There is however data for were obtained by interpolating the measurements carried out on the three available data from Po di Pila (UIPO 1940) mouths from 1927 1970 to 2010. The flow rate obtained to 1938, those provided by ENEL (1990, from the sum of the 1991) relating to the measurements car- measured values in ried out from 1972 to 1991 on the mouths the three mouths is indicated as QPILA. of the Po Pila and Po di Tolle.

14 As of 2002, ARPA Veneto, ARPA expressed as a percentage of the aver- The Busa di Levante or Dritta is the Emilia Romagna and the Consorzio di age flow at Pontelagoscuro, is also af- central mouth of the Po di Pila and most Bonifica Delta del Po have carried out fected by morphological changes and of the flow that comes from this distribu- four studies to assess the flow rate dis- variations to hydraulic efficiency in the tary is carried out to sea. The compari- tribution of these two delta distributar- Po di Pila distributary as a whole. It is son between the recent measurements ies. The distribution of the Po di Tolle possible to partly exclude these effects and the historical data (see Figure 8) (Bocca di Tolle, Busa Storiona and Busa when comparing flow values measured shows a marked reduction in hydraulic del Bastimento) was only investigated at the Busa di Tramontana with the flow efficiency over time of the Busa which, in the 2007 and November 2010 cam- of the Po di Pila (see Figure 7b. The avail- compared to the average daily flow at paigns (Table 2). ability of data relating to measurements Pontelagoscuro, now stands between carried out over the past 40 years, in 20 and 30%. In the 1920s and 1930s, the The Po di Pila Mouths: Busa di this case allows the calculation of the Busa di Levante was capable of dispos - Tramontana, Busa di Levante and flow percentage difference between the ing of up to 50-60% of the total flow of Busa di Scirocco Busa di Tramontana and the Po di Pila the Po River. Measurements carried out by means of a power law, the results of by ENEL from the 1970s to the 1990s had From the data available for the Busa which are shown in Figure 7b. already revealed a significant decrease di Tramontana (Figure 7) one can see that, except for some measurements carried out in the 1930s by UIPO that show higher distribution, there is a Figure 8a: growth trend between the flow at Pon- percentage of average daily flow telagoscuro and the hydraulic efficiency at Pontelagoscuro of the Busa di Tramontana. This trend, carried into the sea from the Busa di on the basis of available historical data, Levante. Graphic shows flow of less than 1,800 m3/s at comparison between the measurements Pontelagoscuro to be more pronounced. and the recent For outflow of up to 5,000 m3/s, there available data. is a reduction in the hydraulic efficiency increase rate of the Busa di Tramon- tana (also confirmed by the most recent surveys), which tends to be reflected in values between 10 and 13 % of flow at Pontelagoscuro.

The higher distribution levels of col- Figure 8b: lected data with flow of less than 1000 percentage of flow carried by the 3 m /s at Pontelagoscuro (the experimen- Busa di Levante tal data seem to indicate a significant compared to the total flow of the Po reduction in hydraulic efficiency from di Pila. The results 1940 to 1990 in “low stage” conditions) of the comparison may in part be due to the inherent dif- were obtained by interpolating the ficulties in carrying out flow measure- available data from ments in river sections subject to tidal 1970 to 2010. The flow rate obtained regimes and frequent changes that af- from the sum of the fect the riverbeds near the mouths. It measured values in the three mouths should be underlined that the hydraulic is indicated as efficiency of the Busa di Tramontana, QPILA.

15 The Po Delta Lagoons October 2013

The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

in efficiency compared to the values re- (with an overall flow of less than 500- general, covers between 1 and 6% of the corded in from previous studies, mainly 600 m3/s) in which the data collected flow rate at Pontelagoscuro, and can be for flow of less than 2,000 m3/s at Pon- by ENEL seem to show an increase in considered fairly stationary over time telagoscuro. hydraulic efficiency at the mouth, com- with weak variations in relation to the Po pared to the Visentini historical data. River hydrometric regime (Figure 9). Such a marked reduction in the effi- Analyzing the most recent data (1970 ciency of the Busa di Levante compared to 2010) one can see a certain inertia of In more detail, again in Figure 9, one to flow at Pontelagoscuro is partly linked the flow capacity of the Busa di Levante can see that at one time, based on his- to the reduction in overall efficiency of in all hydrometric river conditions, with torical data, the efficiency of the Busa the Pila distributary. By comparing the a slight tendency to decrease with flow di Scirocco was greater than 3% in “low flow values measured at the Busa Dritta channeled to augment the total flow of stage” conditions, while medium and with total flow of the three mouths it is the Po di Pila (Figure 8). “high stage” hydrometric conditions re- clear how, as of the 1920s up to today, ported less than 3%. Today this data has the hydraulic activity of the Busa di Le- The Busa di Scirocco is the mouth changed slightly due to a growth trend of vante has generally decreased, except of the Po di Pila characterized by low - efficiency in “high stage” regimes. If one for low water hydrometric conditions est hydraulic capacity. Its efficiency, in analyzes the distribution of flow measured in the Busa di Scirocco compared to the total value of the three mouths of the Po di Pila, the efficiency of this delta

Figure 9a: distributary seems to have increased percentage of over time. The average value for the pe- average daily flow at Pontelagoscuro riod 1927-1939 amounts to 5.2%, while carried into the sea the average value for the period 1970- from the Busa di 2010 (excluding the two measurements Scirocco. Graphic comparison between carried out by ENEL in exceptional low the measurements water conditions) amounts to 8.5%. and the recent data available. The last studies (2002-2010) seem to confirm a slight increase in the effi- LOW water MEDIUM water HIGH water ciency of the Scirocco distributary with higher values than those reported in the historical data for flow in the Pila distributary exceeding 900 m 3/s. However, for overall flow of less than 500 m3/s one Figure 9b: percentage of flow detects a sudden increase in hydraulic carried by the activity of this delta distributary (in rela- Busa di Scirocco compared to the tion to the hydraulic behavior patterns total flow of the Po of the three mouths to the sea of the Po di Pila. Comparison di Pila), even if the notable tidal motion, trend analytically obtained, based on which is even more significant in the the comparisons case of extremely low flow rates, does proposed for the other Po di Pila not always permit for the easy and ac- mouths. The flow curate simultaneous evaluation of flow rate obtained from the sum of the rates. measured values in the three mouths is indicated as Having already provided the relation- QPILA. ships between the respective flow per-

16 centages carried by the Busa di Tramon- tana and Levante, compared to the total flow of the mouths of the Po di Pila, one can analytically refer to the relationship that shows, once again as a percentage, the flow that is discharged into the sea via the Busa di Scirocco. Figure 9 shows how well the obtained relationship fits with the experimental data.

Mouths of the Po di Tolle: Busa Storiona, Busa del Bastimento and Bocca del Po di Tolle

Two recent measuring campaigns (Table 2) were carried out on the mouths of the Po di Tolle (2007 and 2010). The measurements found in the historical data were from two surveys conducted by ENEL in 1991 and 1992. The recent measurements are not easily comparable to the available historical data, as a result of the different methods of data acquisition and the signiﬁcant changes that the Sacca dei Bonelli has undergone over the last forty years. In more in detail, the 2010 measurements were carried out when the ﬂow rates of the Po di Tolle at Scardovari were approximately 1,100 m3/s, and in 2007 when the discharge at Scardovari was about 400 m3/s, while the ENEL measurements were conducted when the discharge at Scardovari was between 70 and 450 m3/s.

Figure 10: the The comparison of the distribution evolutionary trend of data from the last two surveys did not the Po Grande with progressive weakening show any particular changes in hydrau- in efficiency to the lic efficiency of the mouths of the Po di advantage, in differing ways, of all the Tolle, while there were some values that lateral distributaries. conflicted with those recorded by ENEL. Possible effect of In November 2010, the Sacca dei Bonelli growing sediment deposit more and was completely flooded, preventing the more evident in direct measuring of flow carried by the numerous stretches of the main distributary Busa del Bastimento, which was calcu- of the Po (in the entire lated as the difference from the total of Veneto stretch).

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The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

the Po di Tolle: the result was a hydrau- Comparison of Field hydraulic models. The first is the one- lic capacity equal to 4.4% of the flow of Measurements and Hydraulic dimensional (1D) DELFT Hydraulics So- the Po di Tolle, as opposed to the aver- Modeling of the Events of 2010 bek model implemented by ARPA Emilia age value of the measurements carried Romagna on behalf of AIPO (model im - out in 2007 which were equal to 5.7%, A further phase of the investigation plementations in order to predict flood- albeit under a different hydrometric involved the comparison of flow meas- ing along the Po river course), while the regime. However, the average of the urements taken during low water/ flood second is a two-dimensional (2D) finite ENEL data recorded 1.5 km upstream events in June and November 2010 elements model of the Consorzio Delta of the mouth of the Busa del Basti- and the output hydrographs obtained Po (D’Alpaos e Defina, 1993, D’Alpaos mento between 1972 and 1976 is equal from simulations carried out using two et. al., 1994, Consorzio Delta Po Adige, to 20.3% of the Po di Tolle’s total flow.

These variations can be explained Figure 11: by interventions carried out in the late comparison between the results of the 1980s/early 1990s also relating to the model and data reopening of the connection to the la - obtained in the ﬁeld regardin the June goon corresponding to the branching 2010 event. off of the Busa del Bastimento. This work was carried out as part of management works in the Volta Vaccari cove (Figure 5), with the aim of maintaining the distribution percentage between the two branches of Pila and Tolle.

The UIPO report (1940) shows that, according to measurements taken in 1938 and 1939, the Po di Tolle’s flow distributed between the mouths of Tolle and del Bastimento, equaled 27.3% and 72.2% respectively. At that time, the adaptation of the mouth of the Po di Tolle through the construction of the Busa Storiona in order to facilitate flood outflow to the sea had not yet been fully realized.

According to measurements taken in 2007 and 2010, the Bocca di Tolle carried 17.2% and 17.8% of the Po di Tolle flow measured at Scardovari, close to ENEL’s 1992 value (12.5%). Ac- cording to surveys carried out in 2007 and 2010, the Busa Storiona currently shows considerably high hydraulic efficiency with about 77% of total incoming flow being carried to the sea.

18 2006) implemented by Ipros Ingegneria upstream of the Po di Goro branch (at well represented by both models with Ambientale in the Delta area. Berra, about 45 km downstream from a maximum percentage difference the Pontelagoscuro section) all the way of 6%. However, the Po di Goro dis- The Sobek model used the ADRIA- to the sea. The upstream boundary con- charge is overestimated by both mod- ROMS model tide data as downstream dition is shown in the hydrograph pro- els by between 10 and 13%. Since the boundary conditions, which had in the duced from ARPAER’s Sobek model. 2D Consorzio di Boniﬁca model uses past provided good results with the avail- the Sobek model upstream ﬂow rates able observation points. The 2D Consor- In Figure 11 simulation results for the as boundary conditions, this can re- zio model was applied to a section of the June 2010 event are shown. The Po di sult in a possible overestimation of river that extends from about 3.5 km Venezia measured discharges seem the upstream discharge that may af-

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The Po Delta and the hydraulic efﬁciency of its distributaries and outlets: the state of the art of studies and knowledge

fect the modeling results. Regarding can configure the Consorzio Delta Po’s the other main delta distributaries, 2D model in order to be a useful analy- the 2D model seems to be more accu - sis tool that can also be applied in pre- rate, with differences between 4 and dictive phases, with the appropriate 12%. In particular, the Sobek model foresight required by the noted differ - significantly overestimates the hy- ences between the observed data and draulic efficiency of the Po di Maistra model predictions. On the other hand, and underestimates the flow through the observations obtained may serve the Po di Tolle. One should also note as an additional means of contributing an underestimation in the 2D model to the refinement of the model. of about 20% of the flow rates of the Busa di Scirocco. Conclusions

Regarding the November 2010 The recent measuring campaigns survey, the modeling results seem carried out in different hydrologi - less accurate when compared to the cal regimes (“low stage”, “medium June data. On the other hand the flow stage”, “high stage”) on the Po Delta measurements are also somewhat in- distributaries highlight the significant consistent because of the presence potential of new available technology of some deficits to the balance of the that enables the acquisition of current measured outflow. In particular, be- and flow rate data using more accu - tween the Po di Venezia and the sum rate and less expensive systems than of outflow monitored in the other dis - in the past. On the other hand, the tributaries, there is an apparent “loss” campaigns showed the concrete pos- of about 700 m 3/s. Both the two-di- sibility of retrieving and updating the mensional and Sobek models showed relevant available knowledge base, satisfactory flow rate approximations which consists of a large number of for the Po di Venezia for this event. surveys carried out between 1920 and However, both models’ overestimation 1990, in order to reconstruct trends of the Po di Goro flow is confirmed. that describe the hydraulic operation of the different distributaries, in terms For the Gnocca, Maistra, Pila and of evolution. Tolle distributaries, there is a general overestimation with errors of between The information provided by the 15 and 26% in the 2D model, while the surveys also allowed for the identi - Sobek model discrepancies are much fication of specific needs to improve bigger and follow the same trend seen knowledge regarding behavior pat- in the June event simulations: overes- terns of certain distributaries in dif - timation of the Gnocca, Maistra and ferent hydraulic regimes. The ac- Pila and underestimation of the Po di quired experience is fundamental to Tolle outflows. The Consorzio di Bon- the planning and execution of further ifica model underestimates the Busa measuring campaigns aimed at better di Scirocco’s flow by about 20%. The defining the cognitive framework only 2D model ‘s accuracy in predicting be - partially updated here. havior patterns relating to the Po di Tolle mouths is to be noted. Based on the above data, it is evident how one

20 Bibliography Canali L.; Indagine sulla ripartizione della portata del Po tra i vari rami del Delta e sulla loro attività di deflusso; Giornale del Genio Civile, v 97, no. 12, 19 pp, 1959. Consorzio di Bonifica Delta Po Adige, “Studi Idraulico marittimi nelle lagune deltizie – Lagune di Barba- marco e Canarin”. Rapporto tecnico interno, Sipim s.r.l., 2006. D’Alpaos, L. and A. Defina; Venice Lagoon hydrodynamics simulation by coupling 2D and 1D finite element models. Atti del VIII International Conference on Finite Elements in Fluids - New trends and applications. Barcellona 20-24 sett., 917-926, 1993 Defina A., D’Alpaos L., Matticchio B. - “A new set of equation for very shallow water and partially dry areas suitable to 2D numerical models”. Proceedings of Modelling of Flood Propagation Over Initially Dry Areas, ASCE Eds., Milano 1994. ENEL; Rilievi idrografici nella parte terminale del Delta del Po - Parte I - Descrittiva; ENEL-DSR.CRIS; Re- lazione H1/86 r; 1973. ENEL; Delta Po – Ripartizione della portata del Po di Tolle nei rami terminali; ENEL –DSR – CRIS Servizio Idrologico Relazione 1042; 1992. Fiorotto G., Caroni E. e Clemente P.; Modellazione idraulica, matematica e fisica dello stato di fatto del nodo idraulico Po di Venezia - Po di Goro, Università degli Studi di Trieste, Dipartimento Ingegneria Civile, Sezione idraulica e geotecnica, Trieste, 2002. Grego G., Mioni F.; Aspetti morfologici e idrologici del Delta del Po e confronto con il passato; Seminario di Studi sull’Ecologia del Delta; Parma 11-12 aprile, 1985. Grego G.; Idrologia del Delta del Po – Evoluzione dell’ultimo ventennio; ENEL –DSR – CRIS Servizio Idrolo - gico Mestre (Ve); Convegno sull’ecologia del Delta del Po, Albarella (Ro), 1990. UIPO; Idrografia e Idrologia del Po; Ministero dei Lavori Pubblici, Servizio Idrografico; Pubblicazione n.19, Roma, 1981. UIPO; Indagine sul trasporto solido in sospensione nel Delta Padano relativa agli anni 1960-1961; Annali Idrologici 1962; Parte Seconda, Sezione F, pp 141-152, Parma, 1962. UIPO; La piena del Po del novembre 1968; Annali Idrologici 1968; Parte Seconda, Sezione F, pp 139-154, Roma, 1971. UIPO; Ricerche idrografiche nel Delta del Po; Ministero dei Lavori Pubblici, Servizio Idrografico, Pubblica- zione n.14, Vol. 2, Roma, 1940.

21 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and _STUDIES & RESEARCH 2010 MONITORING THE WATER QUALITY IN THE PO DELTA LAGOONS: ANALYSIS OF CHEMICAL-PHYSICAL PARAMETERS MEASURED BETWEEN 2005 AND 2010

ANGELO RUBINO Since 2005, yearly monitoring cam- Knowledge of a system implies first Università Ca’ Foscari di Venezia paigns have been carried out to record of all, availability of data (primarily PIETRO TRAVERSO the water quality in the lagoons of the experimental, but also data simulated Università Ca’ Foscari di Venezia Po River Delta. Measurements of vari- using numerical models) relating to it.

DR. DAVIDE ZANCHETTIN ous chemical-physical parameters (tem- The natural environment in particular, Max Planck Institute for Meteorology perature, conductibility/ salinity and is a dynamical system: the evolution concentration of dissolved oxygen) were of its descriptive variables and param - taken at regular intervals, especially in eters is continuously shaped by multi - the summer months, in an increasing ple factors, some of which act locally, number of lagoons over the years. To- while others remotely (think for exam- day, these measurements make up an ple, about atmospheric and oceanic important database of the quality of the teleconnections). This characteristic deltaic waters and, after their reanalysis of the system poses problems of both preceding publication, are also available a theoretical and practical nature, in - to scientific research activities. volving primarily the data sampling. Theoretical problems are particularly On one hand this contribution is relevant in extremely dynamic and therefore motivated by the will to broad- varied environments as in the case of en our knowledge of physical, chemical- the lagoon ecotones. physical and biological dynamics in the Delta lagoons. On the other hand, it aims Here in fact, the preferential use at further qualifying the widespread of monitoring sites at fixed loca - commitment to the creation of this data- tions inevitably leads to problems of base, showing the importance of careful representativeness of the data. It is measuring and interpreting for a range known that in these “transition” areas of users. physical-chemical and biological conditions may vary substantially within In particular, this overview analysis both relatively small areas and tem - highlights the complexity of the inter- poral frames. Thus limited (in space actions between different physical pa- and time) representativeness of ob- rameters within the Po Delta lagoons. It servational data represents a major further reveals the existence of notably difficulty in their interpretation, i.e., strong responses to external factors their insertion within a well-defined and the variety of phenomena that are theoretical framework. This implies a at the origin of the aforementioned in- considerable logistical and therefore teractions and responses. A continued also economic effort in the activation flow of information on the parameters of the greatest possible number of describing the water quality in the Po monitoring sites capable of sampling Delta lagoons is therefore indispensable at a sufficient frequency (and for a in such a highly dynamic context that is sufficient time) in order to record the so responsive to external perturbations, dynamics of interest and their vari - not only in order to gain a deeper under- ability. standing of the variability of the system, but also from the perspective of future The complex system of lagoons and usage of this increasing flow of quantita- “sacche” that characterizes the Po Figure 1: 2005-2010 tive information for the management of Delta area provides several emblem- monitoring site positions. such a significant area. atic examples (in particular the Sacca

22 Valle Capitania

Valle Veniera Valle Sagreda

Collettore Padano Polesano

Po di Maistra

Po Della Pila Po di Venezia

Po Delle Tolle

Po Di Gnocca Sacca Degli Scardovari

Po Di Goro

1. Scardovari Internal 2. Scardovari Sea 3. Canarin 4. Basson 5. Vallona 6. Marinetta

23 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

del Canarin and the Sacca degli Scar- the different campaigns, highlight- dovari) of the heterogeneity and ex- ing the two main sampling methods treme variability typical of transition- used: 1) pole-mounted multiparameter al habitats both from a biochemical probe, with sensors constantly sub- and ecological point of view. In fact, in merged in lagoon waters and sampling the different portions of each lagoon Table 1: active sites Station 2005 2006 2007 2008 2009 2010 the evolution of the physical-chemical over the course of characteristics and degree of vivifica- Scardovari Internal B* B* BB B* B* the monitoring. Scardovari Sea BBBB B* B* tion is inextricably tied to hydrody - B: Buoy site; namics, and it is in turn influenced by Canarin -BBBBB B*: Buoy site with deeper extraction; atmospheric circulation, tides, local Vallona - B* BBBB P: Pole site. inflow of freshwater from the different Basson ---PPP distributaries of the Po and its water Marinetta ---PPP towers, morphology / bathymetry and so on. at a fixed height from the bottom, 2) The hydrodynamics therefore also buoy-mounted multiparameter probe contribute on the one hand, to the pro- equipped with hydraulic extraction/ pensity of the different lagoons (and washing system, sampling at a fixed of different regions within a lagoon) depth below the surface. to experience prolonged periods of significant stagnation or, on the oth - In the table, and generally in this er hand, to their different exposures text, the different monitoring sites are to the inflow of riverine freshwater referred to as follows: during flooding events. In particular, 1. Scardovari Internal for the buoy deviations from the natural function - monitoring site in the inner portion of ing of the system linked to the above the Sacca degli Scardovari, in the vi- mentioned factors are of major inter - cinity of the dock; est, since they may lead to disruptive 2. Scardovari Sea for the buoy anoxic events like that affecting the monitoring site in the outer portion of most internal portion of the Sacca de- the Sacca degli Scardovari, near the gli Scardovari during the summer of mouth to the sea, a few meters from 2009. In order to provide an evermore the eastern edge of the Sacca; complete picture of the environmental 3. Canarin for buoy monitoring site conditions in the Po Delta lagoons, the in the central portion of the Sacca del monitoring system of water quality Canarin, north of the northern mouth has evolved over the years, from the to the sea, a few meters from the strip two stations initially set up in the Sac- of land which separates the artificial ca degli Scardovari (2005 campaign) canal west of the lagoon; to the six active stations in the Sacca 4. Basson for the pole monitoring degli Scardovari, Sacca del Canarin, site in the central portion of the Sac- and in the Marinetta, Basson and Val- ca del Basson, a few hundred meters lona lagoons during the 2008, 2009 north of the southern mouth to the and 2010 campaigns. sea; 5. Vallona for the buoy site moni - Table 1 summarizes the character - toring in the central portion of the La- istics of the monitoring system for guna di Vallona, north of the bend;

24 6. Marinetta for the pole monitor- using, above all, statistical methods technical aspects, such as the detailed ing site in the central portion of the designed to identify correlations not description of the sampling systems Laguna di Marinetta. only between the different variables or the validation phase prior to pub - measured, but also between them lication of data. For these technical The approximate location of the and additional variables, be they lo - aspects, the reader should refer to the monitoring sites is shown in Figure 1. cal or representative of larger-scale technical reports produced at the end The data described and analyzed in conditions. In this way it is possible of each campaign. this paper refer to the following pa - to contextualize the measured vari - rameters: temperature, salinity, and ability in the quality and character - Figure 2 compares the data meas- dissolved oxygen, sampled at three- istics of the lagoon waters with lo - ured in the Sacca del Canarin during hour intervals or less. cal and larger-scale weather and the 2007, 2008 and 2009 campaigns. climate dynamics. In this context, The evolution of water temperature is Based on the framework outlined this study focuses on the analysis of characterized by notable similarities above and in order to minimize, or at daily-average values, which are in - between the different years, originat- least greatly limit the inevitable un - cluded in our database if calculated ing in the prevalence of the seasonal certainties related to the spatial and on a basis of at least five measure - cycle over the other sources of vari - temporal constraints of the sam - ments throughout the day. ability: between August and Septem- pling, we chose to focus on an over - ber, for example, temperatures can view analysis of the available data However, it glances over the more be on average up to 10 °C warmer

Comparison of temperature data (temp), salinity (sal) and dissolved oxygen (DO)

Canarin Vallona 2006 2006 40 2007 40 2007 2008 2008 30 2009 20 2009 20 2010 2010 temp (°C) temp (°C) 10 0 M J J A S O N M J J A S O N 40 40

30 20 20 Sal (‰) Sal (‰) 0 10 M J J A S O N M J J A S O N

20 20

10 10 OD (mg/L) OD (mg/L) 0 0 M J J A S O N M J J A S O N months of the year months of the year

Figure 2: Figure 3: comparison of comparison of temperature data temperature data (temp), salinity (temp), salinity (sal) and dissolved (sal) and dissolved oxygen (DO) oxygen (DO) measured at Canarin measured at Vallona over the 2006-2010 over the 2006-2010 monitoring period. monitoring period.

25 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

than those recorded in early spring thus often be monitored via remote salinity shows marked differences and late autumn. As we shall see, sensing, in particular radar-based between the campaigns, especially in dominance of the seasonal cycle is a tools, which measure the modulation July. The salinity data are consistent common feature of temperature evo - of small-scale waves generated by the in relative values with those meas - lutions in all the monitored lagoons. presence of substances at the surface ured in the Sacca del Canarin: the wa- The temperatures consistently indi- or by alterations of the surface veloc- ters are markedly saltier in July 2007 cate values of above or around 25 °C ity field. and fresher in July 2009. from late June to late August, only occasionally exceeding the threshold The dissolved oxygen data provide As with the Sacca del Canarin, dis- of 30 °C (with the exception of 2006 a substantially consistent picture of solved oxygen data provide a sub - and 2010, when there were several the general temporal evolution over stantially consistent picture of the cases of consecutive days with tem - the course of the various monitor - general temporal evolution over the peratures higher than this threshold). ing campaigns. This is characterized course of the various monitoring Autumn is generally characterized by by minimal seasonal variations (the campaigns. The yearly evolution is rapid decreases in temperature (of data generally remain around 7-8 characterized by minimal seasonal up to almost 10 °C within a couple of mg/l over the course of the year) with variations, with values generally re - weeks) interspersed with seemingly a tendency to produce minimum val - maining around 7-8 mg/l. Interesting- stationary phases that were less ap - ues (about 5 mg/l, still higher how - ly, the data collected during the late parent in 2010. ever than anoxia risk levels) in July spring of 2008 indicate a progressive and August. Nonetheless, like the decrease in dissolved oxygen with The salinity shows marked differ- other parameters dissolved oxygen is marked peaks likely highlighting algal ences between the different years, sampled close to the surface and in bloom episodes. We remark that dis - especially in July-August and in the an area exposed to flow/ebb tide. The solved oxygen is sampled at the sur - autumn, when the gap between the inner zones and deeper layers of the face, like the other parameters. The individual years reaches values above Sacca del Canarin may have experi - inner zones and deeper layers in the 10 parts per thousand. This variability enced periods in which the values of lagoon may have experienced periods is partly due to the variability in the dissolved oxygen fell well below those in which the values of dissolved oxy - freshwater inflow from the river Po, monitored. gen fell well below those monitored. and in part due to the sampling loca - tion at the front, of tidal origin, be - Figure 3 compares the data meas - Figure 4 compares the data meas - tween internal and open-sea waters. ured in the Vallona lagoon during the ured at the Scardovari Internal site On site surveys have in fact shown 2006-2010 campaigns. Considera- during the 2005-2010 campaigns. that in the area surrounding the sam - tions about the observed interannual The yearly evolution of water tem - pling site variations in surface salin - variability are similar to those made perature is characterized by the typi - ity (as sampled at 0.5 m depth) in the for the Sacca del Canarin. Water tem- cal dominance of the seasonal cycle order of tens of parts per thousands perature evolution is characterized over the other sources of variability. can occur within just a few meters. by a substantial dominance of the Unlike the previously examined la - seasonal cycle over the other sources goons, large inter-annual variability This situation of great frontal vari - of variability. Over the five years of is observed during hot periods, with ability is common in areas near riv - monitoring, the temperature consist- differences reaching 7-8 °C in late erine mouths or estuaries. The sea - ently reaches values above 25 °C be - June and in August. Moreover there water-freshwater front is sometimes tween late June and late August, only is evidence of episodes of several very sharp, and is generally linked occasionally exceeding the threshold days, in which the temperature ex - to phenomena of convergence of the of 30 °C. Autumn is characterized by ceeds the threshold of 30 °C. These surface velocity field and/or to the rapid decreases in temperature simi - occurred once or more times a year accumulation of material floating on lar to those found in the Sacca del Ca- (as in 2005) and in different periods the surface. Such discontinuity can narin, though of lesser intensity. The in the different years (for example be-

26 tween June and July in 2008 and in and Vallona. These episodes can be the mass balance of water in the re - the second half of August in 2009). attributed to the sudden intrusion of gion (precipitation - evaporation + ex- cold air typically brought by autumnal ternal sources/sinks), which typically This indicates a greater suscepti - weather perturbations. shows a lower interannual variability. bility of this portion of the lagoon to extreme weather events, such as pro - The salinity shows marked inter- As with the Sacca del Canarin and longed periods of warming calm condi- annual variability up to the month of Vallona, the salinity data indicates tions. This portion of the lagoon is in August. With the exception of 2010, a markedly saltier waters in 2007, with fact only marginally affected by tides phase of extremely reduced interan- comparable values in July 2005- and turns into a stagnant pond during nual variability sets in autumn, with 2006. Opposite trends in July charac- calm periods. The dissolved oxygen average values of 28-29 parts per terize the years 2008 and 2009, spe - data, and the anoxia episode of late thousands and deviations, in indi - cifically with an increase in the former August 2009 in particular, confirm vidual years, of only a few parts per and a decrease in the latter. Salinity this picture. We remark again that, thousands. The strong mixing forced values measured at the beginning of like the other parameters, dissolved by the autumnal winds is the likely the 2009 campaign are decidedly low oxygen was sampled at the surface. explanation for this behavior. The on - and concurrent with high values of Autumn is characterized by rapid set of quasi-homogeneous conditions dissolved oxygen, which may be due decreases in temperature similar to through the water column implies that to both, the particularly rainy preced - those found in the Sacca del Canarin salinity is essentially determined by ing winter (that of 2008-09) and the

Comparison of temperature data (temp), salinity (sal) and dissolved oxygen (DO)

Scardovari Internal Scardovari Sea 2005 2005 40 2006 40 2006 2007 2007 30 30 2008 2008 20 2009 20 2009 temp (°C) 2010 temp (°C) 2010 10 10 M J J A S O N M J J A S O N 40 60

40 20 20 Sal (‰) Sal (‰) 0 0 M J J A S O N M J J A S O N

15 15 10 10

5 5 OD (mg/L) OD (mg/L)

0 0 M J J A S O N M J J A S O N months of the year months of the year

Figure 4: Figure 5: comparison of comparison of temperature data temperature data (temp), salinity (sal) (temp), salinity (sal) and dissolved oxygen and dissolved oxygen (DO) measured at (DO) measured at Scardovari Internal Scardovari Sea over over the 2005-2010 the 2005-2010 monitoring period. monitoring period.

27 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

accentuated recirculation of waters tween the two datasets emphasize the ceed the threshold of 30 °C over the artificially induced during that period. different dynamics that characterize course of the year, if not sporadically. Unlike the Sacca del Canarin and Val- the two portions of the lagoon. Tem - lona, a seasonality is noticeable in perature evolution is characterized by Autumn is characterized by the typi- the dissolved oxygen data from Scar- the typical dominance of the seasonal cal rapid cooling events observed in the dovari Internal, with minimum val - cycle over other sources of variability. other lagoons. Like the innermost por- ues typically occurring in the hottest The year 2005 is characterized by a tion of the lagoon, interannual variabil- months (July-August). This period of seemingly anticipated seasonal cycle, ity in the annual evolution of salinity is scarce oxygenation is followed by a with a warmer June and colder Au - markedly large until August and strong- growth phase (several mg/l) in Sep - gust compared to the other years. ly reduced in autumn, when values tember. range between about 27 and 30 parts This distinctive feature occurred, per thousands. Also in this site, gener- Figure 5 compares the data meas - however, within a context of large in - ally lower salinity values make the year ured at Scardovari Sea during the terannual variability with differences 2010 exceptional compared to previous 2005-2010 campaigns. Despite the of up to 3-4 °C between the values years. Like Canarin and Vallona, the sa- data bearing similarities, in their gen- measured in individual years. Unlike linity data show markedly saltier waters eral traits, to those measured in the the inner portion of the lagoon, and in 2007, with values comparable to July innermost portion of the sacca (Fig- similar to Canarin and Vallona, the 2005-2006 and, if only for a short time, ure 4), substantial differences be - maximum temperature does not ex- July 2010.

Comparison of temperature data (temp), salinity (sal) and dissolved oxygen (DO)

Marinetta Basson 2008 2008 30 2009 40 2009 2010 30 2010 20 20 temp (°C) temp (°C) 10 10 M J J A S O N M J J A S O N 40 40

20 20 Sal (‰) Sal (‰) 0 0 M J J A S O N M J J A S O N

10 20

5 10 DO (mg/L) DO (mg/L)

0 0 M J J A S O N M J J A S O N months of the year months of the year

Figure 6: Figure 7: comparison of Comparison of temperature data temperature data (temp), salinity (sal) (temp), salinity and dissolved oxygen (sal) and dissolved (DO) measured oxygen (DO) at Marinetta over measured at Basson the 2008-2010 over the 2008-2010 monitoring period. monitoring period.

28 Salinity Dissolved oxygen Projection of the variables on the factor-plan (PC1xPC2) Projection of the variables on the factor-plan (PC1xPC2)

SEA INTERNAL SEA

INTERNAL

Figure 8: projection Slightly saltier waters are further- generally features rapid decreases in of the variables more noticeable in July and August temperature similar to those found in (different monitoring stations 2009 compared to the same period in the other lagoons. Salinity does not in this case) in the 2008. The low salinity values meas - typically show marked variations over plan defined by first and second principal ured at the beginning of 2009 further the three years of monitoring, settling components (PC1 support the hypothesis of a particu - in the July to October period with and PC2) extracted larly rainy 2008-09 winter. Like the values of 27-30 parts per thousands. from the salinity (left) and dissolved inner portion of the sacca, a seasonal The 2009 and 2010 data indicate that oxygen (right) data. component is discernible in the dis - extremely low salinity values can be The position (x,y) of each variable solved oxygen data. A noticeable measured during spring, in episodes in the factor- feature is the gradual depletion of (as in 2010) as well as over longer pe - plan reflect its correlation with PC1 oxygen measured in 2009 and culmi - riods (as in 2009). In fact this lagoon (x coordinate) and nating at the end of August, with min - is among those that are more exposed PC2 (y coordinate). “PO” indicates imum values of almost 5 mg/l below to flooding by the Po River freshwa - the position of those observed in the same period in ters, especially coming from the Po “the daily Po other years. di Levante branch, which serves as a River discharge at Pontelagoscuro” in collector for the Fissero, Tartarus and the factor-plan. Figure 6 compares the data meas - Canalbianco canals. The dissolved ured in the Marinetta lagoon for the oxygen data show a certain stability period 2008-2010. Temperature evo- throughout the year, with values typi - lution is characterized by the typical cally around 6-7 mg/l. prevalence of the seasonal cycle over the other sources of variability. As con - Figure 7 shows the data measured firmed by the 2008 data, the autumn in the Basson lagoon that are only

29 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

Figure 9: time series of daily Po River discharge at Pontelagoscuro for the period January 2005-October 2010. Discharge (m^3/s) (m^3/s) Discharge

Date (month/ day/ year)

available, like those of Marinetta, for and 2010 on the dynamics of the la - fact that the latent variables are mu - the period 2008-2010. Temperature goon. In fact this sacca is among tually orthogonal, or describe linear - evolution resembles that found in those that are most exposed to flood- ly independent portions of variability other lagoons. In particular, temper- ing by the waters of the Po as it bor - in a descending order of explained atures stabilize above 25 °C in July ders the Pila distributary. The dis- variance. and August, never exceeding (except solved oxygen data show a marked for one episode in 2010) the thresh - stability throughout the year, with Focusing the analysis on the first old of 30 °C. Autumn is character - values typically around 5-10 mg/l. variable/s extracted, it is therefore ized, especially in 2008 and 2009, possible to reduce the complexity of by the same typical rapid decreases There are therefore various tem - the phenomenon described by the ini - in temperature observed in the other perature, salinity and dissolved tial data, neglecting minor contribu - lagoons. The limited amount of avail - oxygen data for the Po Delta area, tions to the total variability (i.e. the able data (from only three monitoring “simultaneously” available for the higher-order principal components campaigns) does not allow for a clear various lagoons. Multivariate statis- extracted). This paper presents a assessment of the interannual vari - tical analysis techniques permit the PCA analysis carried out, separately ability of salinity. In the long term, analyzing of these various, often cor - for each parameter, on daily-average one notes the substantial stability related or interacting descriptors. data of temperature, salinity and dis - between August and October, super- The aim is often to reduce the size solved oxygen from the monitoring posed by several positive and nega - of a multivariate system in order to campaign in 2009. In fact, only dur - tive excursions. The spring and early simplify the interpretation of it func - ing this campaign data were recorded summer periods, for which data are tioning as a whole. Principal compo - in all the lagoons over a sufficiently only available for 2009 and 2010, are nent analysis (or PCA), in particular, long period (three months or longer, characterized by a positive trend in is a statistical technique aimed at the using different parameters) to allow salinity, in which large approximate - simplification of multivariate data. It for a robust analysis. Nonetheless, ly weekly and bi-weekly fluctuations allows one to extract a new set of “la- the results of a PCA analysis con - overlap. The extremely low salinity tent” variables (called principal com - ducted on the 2010 data will also be values measured in June confirm the ponents) from an original set of data discussed where necessary. hypothesis of a strong influence of through a linear transformation. The the particularly wet springs of 2009 advantage of the technique lies in the Regarding temperature, data meas-

30 Figure 10: Comparison between Sal and Po River discharge: 2008 comparison between Po River discharge at Pontelagoscuro and salinity measured in the Po Delta lagoons in the 2008 (top table), 2009 (middle table) and 2010 (bottom table) monitoring periods. The axis is inverted for salinity Po River discharge (m^3/s) (m^3/s) discharge River Po (ordinates on the left). per thousand) (parts Salinity

Day of the year

KEY: Comparison between Sal and Po River discharge: 2009

SEA Po River discharge (m^3/s) (m^3/s) discharge River Po Salinity (parts per thousand) per thousand) (parts Salinity

Day of the year

Comparison between Sal and Po River discharge: 2010 Po River discharge (m^3/s) (m^3/s) discharge River Po Salinity (parts per thousand) per thousand) (parts Salinity

Day of the year

31 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

ured during the 141 days in which they salinity values in spring and higher sa - are available for all the lagoons were linity values in summer (Figure 8). considered. The data are very strong - ly correlated, which confirms a clear As for temperature, this variability predominance of the seasonal cycle is associated with the seasonal cycle, and very small differences, in terms which derives from the seasonal cycle of relative variations, in the evolution of Po River discharges and from the of temperature in the different la - difference between precipitation and goons. These high correlation values evaporation. This hypothesis is sup- are reflected in the calculation of a ported by the position of the daily Po first principal component (PC1) largely River discharges1 in the factor-plan in- dominating the total variability, and dicating good correlation with PC1 and accounting for 98.2% of the total anticorrelation with the salinity data. variance. PC1 describes the tendency, The second principal component ex - common in all the lagoons, to have tracted (PC2) accounts for about 21% above or below average temperatures of the total variance, and therefore (for this reason it essentially captures describes an important part of the the seasonal temperature cycle). The system’s variability. second principal component extracted (PC2) accounts for 0.81% of the total It highlights the existence of two variability. It highlights the existence distinct patterns, one represented by of two opposing patterns, one repre - Vallona and Marinetta, and the other sented by Vallona and Scardovari In- by the remaining lagoons, with Scar- ternal, and the other by the remaining dovari Internal particularly “isolated” lagoons. Given the characteristics of compared to the other stations and in the groups of stations obtained in this clear anticorrelation with Vallona and way, it is possible that this component Marinetta (Figure 8). Given the char - discrminates between the stations acteristics of the groups of stations close to the sea and those further obtained in this way, it is possible that away. this represents the common depend - ence of Vallona and Marinetta on the Regarding salinity, data measured Po di Levante discharge regime. It is during the 131 days in which they are conceivable that PC2 also describes available for all the lagoons were con - the response of the lagoons to the pre- sidered. In this case, the correlations vailing wind direction during flooding between the data of the different sta - episodes. tions can be close to zero, as for in - stance between salinity of Scardovari Regarding dissolved oxygen, data Internal and Marinetta. This implies measured during the 126 days in which greater variability in this parameter in they are available for all the lagoons the values simultaneously expressed were considered. As for salinity, the 1 Daily-average Po River discharge data are provided by ARPA-Emilia Romagna, Servizio Idro- in the various lagoons. This results in data pertaining to the various moni - meteorologico. The data refer to the Pontela- a first principal component (PC1) that toring stations can be characterized goscuro (FE) section, which is located about 90 kilometers upstream of the river delta and is the accounts for 60% of the total variabil - by very low correlations. This is the last measurement site not affected by tides (for ity of salinity in the Delta lagoons, and case, for example, with the correla - an introduction to the Po River discharge data at Pontelagoscuro, see, e.g., Zanchettin et al. which is related to the tendency, com - tion between dissolved oxygen meas - 2008). mon to all the lagoons, to have lower ured in Marinetta and in Basson.

32 Figure 11: Comparison between DO and Po River discharge: 2008 comparison between Po River discharge at Pontelagoscuro and dissolved oxygen measured in the Po Delta lagoons in the 2008 (top table), 2009 (middle table) and 2010 (bottom table) monitoring periods. Dissolved Oxygen (mg/l) (mg/l) Oxygen Dissolved Po River discharge (m^3/s) (m^3/s) discharge River Po

Day of the year

KEY: Comparison between DO and Po River discharge: 2009

SEA Dissolved Oxygen (mg/l) (mg/l) Oxygen Dissolved Po River discharge (m^3/s) (m^3/s) discharge River Po

Day of the year

Comparison between DO and Po River discharge: 2010 Dissolved Oxygen (mg/l) (mg/l) Oxygen Dissolved Po River discharge (m^3/s) (m^3/s) discharge River Po

Day of the year

33 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

This implies a considerable variability over the period 2005-2010 are shown influenced by the competition be- in the values of this parameter simul - in Figure 9. Even at first glance one tween local biological activity, which taneously expressed in the various la - can clearly see a trend towards higher is closely linked to temperature and goons. discharges, with maximum values in ventilation, which is closely linked to 2009 both in terms of drought and watermass circulation, which is in turn Notably, the correlation between flood events. determined by the combined effects of the two stations in the Sacca degli wind and tides. It should be noted that Scardovari indicates that dissolved The absolute minimum recorded in the event of a major flooding, such oxygen series in the outermost and in- in the period 2005-2010 amounted as that of spring 2009, the waters of nermost portions share, linearly, only to 168 m3/s, measured on 22 July fluvial origin are generally poorly oxy - about 25% of the variability. These 2006, while the absolute maximum genated because of the considerable correlation values translate to a first amounted to 7403 m 3/s, measured turbulence, which makes them muddy, principal component (PC1) that ac- on 2 May 2009. It is also interesting increasing the sediment load and ham - counts for about 45% of the total var - to note that winter/spring 2008/09 pering photosynthetic processes. iability of dissolved oxygen in the la - was characterized by a number of ma - goons (see Figure 8) and is associated jor flood events with peaks exceeding The propagation of these waters with the tendency, common to all the 4000 m3/s. In contrast, the spring of inside the lagoons, although contrib - lagoons, to show lower levels of dis - 2005 was characterized by an almost uting to the recirculation of water, solved oxygen in the summer period. constant discharge below 2000 m 3/s, especially closer to the surface, may emphasizing below-average basin pre- therefore be associated with relatively The second principal component cipitation in that period. low levels of oxygen (as observed in extracted (PC2) accounts for about spring 2009 in Marinetta and Cana- 20% of the total variance, describing Figures 10 and 11 compare, as ex - rin). A lag-correlation analysis (results therefore, for the salinity, an impor - amples, the Po River discharge in the not shown) between the Po River dis - tant part of the system’s variability. It years 2008, 2009 and 2010 and salin- charges and salinity and dissolved ox- highlights the existence of two practi - ity and dissolved oxygen data meas- ygen around the flooding in April-May cally opposing patterns, that of B as- ured in the same years in the differ - 2009, sheds light on the dynamics son and Scardovari, and that of Mari- ent lagoons. The salinity time series behind the propagation of saline and netta and Vallona (Figure 8). Given overlap, once the scale is reversed, dissolved oxygen anomalies in the dif- the characteristics of the groups of with the Po River discharge data (Fig - ferent lagoons of the Delta. stations obtained in this way, it is pos - ure 10), indicating that periods of high sible that, for the salinity, this repre - discharges generally coincide with a As for the dissolved oxygen, in sents the common dependence of Val- decrease in the salinity of the lagoon some cases (Scardovari and especially lona and Marinetta on the discharges’ waters. This is particularly evident Basson) there is a tendency towards regime of the Po di Levante. The posi- in the case of the late spring floods positive correlations when a delay of tion of the daily Po River discharges (April-May), especially in 2009, when a few days is imposed upon the dis - in the factor-plan indicates that they the exceptionally high flooding of the charge data, suggesting that in these play a potentially important role in the Po (over 7000 m3/s) coincided with sa- lagoons the freshwater input helps to variability expressed by PC2, but not linity values in Basson below 5 parts dynamize the circulation in the medi - that of PC1. per thousands. um term. It should be noted, however, that in Canarin the flooding seems to The multivariate analysis highlight- Generally, the dissolved oxygen be associated with a delayed reduction ed several potentially important im- does not show a clear link to the Po in dissolved oxygen. plications of the Po River freshwaters discharges apart from the overlap- on the variability of chemical-physical ping of trends in the summer period This confirms the complexity of parameters in the Delta lagoons. The (June-August) (Figure 11). The amount possible interactions between Po Riv- Po River discharge data measured of dissolved oxygen is in fact strongly er discharges and individual lagoons,

34 Correlation between Temp PC1 and surface air temperature Correlation between Temp PC2 and surface air temperature

72°N 72°N

60°N 60°N

48°N 48°N

36°N 36°N

24°N 24°N

0° 0° 25°E 25°E 75°W 75°W 25°W 25°W 50°W 50°W

-1 -0.5 00 .5 1 -1 -0.5 00 .5 1 corr coeff corr coeff

Correlation between Temp PC1 and surface air Correlation between TempPC2 and surface air (detrended data) (detrended data)

72°N 72°N

60°N 60°N

48°N 48°N

36°N 36°N

24°N 24°N 0° 0° 25°E 25°E 75°W 25°W 75°W 25°W 50°W 50°W

-1 -0.5 00 .5 1 -1 -0.5 00 .5 1 corr coeff corr coeff

Figure 12: top Euro/Atlantic sector. panels: Correlation Bottom panels: between the ﬁrst same as top panels, and second principal but for data from components (PC1 which the long- and PC2) extracted term component, from the daily as determined by temperature data a second-order for the year 2009 polynomial ﬁt to and surface air the time series, has temperature for the been removed.

35 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

Figure 13: comparison between the near- surface water temperature, salinity and dissolved oxygen at the Scardovari Internal site and a selection of large- scale atmospheric circulation indices Salinity (‰) (left panel). All Temperature (°C) data are monthly- Dissolved Oxygen (mg/L) averages for the month of July.

year year year year

which are determined not only by the al., 1996) reanalyses for the period from ture observed along the North American influence of the riverine waters on local 01/01/2009 to 31/12/2009. The data are East coast, up to the inner portion of the hydrodynamics, but also on other im- provided by NOAA / OAR / ESRL PSD, Labrador Sea. The correlation pattern portant quality parameters such as tur- Boulder, Colorado, USA, and can be ac- extends along the coast of Greenland, bidity. Regarding salinity, the Po River cessed at: http://www.esrl.noaa.gov/ but near-zero correlations are observed flooding contributed to a general reduc- psd/. over the tropical and north-east Atlan- tion of salinity in the various lagoons, al- tic, which is rather strongly correlated though correlations are significant only In order to facilitate the description with PC2. for Marinetta. of the relationship between the two variables, principal components extracted This distinct pattern is particularly in- The lag analysis indicates that fluctu- from the Po Delta lagoons’ water tem- teresting, as it underlines how the evo- ations in the discharge and salinity sig- perature data (PC1 and PC2) were used lution (including seasonal) of Euro-Med- nals are essentially contemporaneous, rather than the original data. In fact this iterranean regional climates depends with a slight advance of the discharge allows one to limit the description to just strongly on the generation of perturba- signal (a few days) in Basson a n d Canarin. two variables that nonetheless describe tions in the Atlantic that occurs along Local factors, such as the freshwater in- most of the total variability of the origi- the east coast of North America. Similar flow associated with different wind pat- nal data. In this case, to further facilitate correlation analysis carried out for PC1 terns, are therefore extremely impor- the reading of the spatial correlation and sea-level pressure grid-data identi- tant to the variability and heterogeneity structures, PC1, which was inversely fies a dipolar structure over the North of the physical-chemical properties in correlated with the original data (Figure Atlantic, consisting of a negative corre- the deltaic area. It should be noted that 8), was inverted before the correlation lation centre over Scotland, and a belt of local weather (temperature, precipita- analysis. The analysis was carried out positive correlations over the subtropi- tion, wind, etc.) is intrinsically linked to for all the days for which PC1 and PC2 cal North Atlantic. The thus identified the larger scale meteorological dynam- were calculated. dipole resembles the positive phase of ics (Zanchettin et al., 2009). a teleconnection (i.e. a mode of large- The spatial structures (patterns) of scale atmospheric variability) known as It is interesting for example, to com- the correlations for near-surface air the East Atlantic pattern (EA). pare the Po Delta lagoons’ water tem- temperature in Figure 12 (upper panels) perature data measured throughout show that PC1 is well correlated, as one It is evident that these correlations 2009 with the surface air grid data would imagine, with the temperature in depend heavily on the seasonality of available for the Euro-Atlantic region. the Mediterranean area (especially the both PC1 and the grid-data. It was there- The climate data are the daily average western basin) and Central Europe. PC1 fore decided to carry out a further ‘NCEP / NCAR reanalysis 1’ (Kalnay et is also well correlated with the tempera- analysis on detrended data, i.e., on data

36 Surface air temperature anomalies for the period 2005-2010, DJF Surface air temperature anomalies for the period 2005-2010, JJA

-5 -4 -3 -2 -1 0 1 2 3 4 5 -1.5 -1 -0.5 0 0.5 1 1.5 2

anomaly (°C) anomaly (°C)

Figure 14: surface air temperature cleared from the long-term variability transporting warm air from Africa to- anomalies for component (in this case the seasonality), wards North Italy and colder continental winter (December- February, left panel) in order to characterize the relationship air from the Balkans towards Egypt. In and summer (June- between local and large-scale dynamics an attempt to gather more evidence to August, right panel) over the period at shorter timescales, particularly those support the hypothesis of a strong link 2005-2010 relative ranging from several days to weekly/ between large-scale atmospheric dy- to the climatology of multiple weeks. In this case (Figure 12, namics and changes in the water char- the last ~ 60 years. lower panels), the link between PC1 and acteristics of the Po Delta lagoons, the surface air temperature becomes much interannual evolution of monthly-aver- more local, with a strong positive corre- age temperature, salinity and dissolved lation centre above Italy associated with oxygen recorded in Scardovari Internal a belt of negative correlations in the at the surface for the month of July was south-east. compared with that of a selection of indices of large-scale atmospheric vari- This structure corresponds to a posi- ability. tive sea-level-pressure anomaly over the Ionian Sea, which contributes to These include the already mentioned an anomalous anticyclonic circulation NAO and EA indices, the Paciﬁc-North

37 The Po Delta Lagoons October 2013

Monitoring the water quality in the Po Delta lagoons: analysis of chemical-physical parameters measured between 2005 and 2010

American (PNA) index, the East-At- dinavia and continental Europe and be- system. In particular it has evidenced a lantic/Western Russian (EAWR) index low average over the Iberian peninsula marked heterogeneity not only between and the Scandinavian (SCA) index. The and north-western Africa. the various lagoons, but also within each monthly values of these indexes were of them, and has identified important made available by the NOAA-Climate Above average temperatures are also components of interannual variability, Prediction Center at: http://www.cpc. observed over the Ionian Sea and over not only on a local scale but also linked ncep.noaa.gov/data/teledoc/telecon- the eastern Mediterranean basin in gen- to large scale dynamics. tents.shtml. The decision to limit the eral. In summer one notes above aver- analysis to the month of July and to the age temperatures almost everywhere, It is therefore essential to continue Scardovari Internal station is linked to with anomalies of around one degree the monitoring, extending the quantity the fact that there is a sufficient amount centigrade in the Ionian and southern of observed data to larger areas and of average daily data to ensure a reliable Adriatic regions. Looking at seasonal over longer timeframes. The fine tuning monthly-average value for this month temperature data on the hemispheric of numerical models used in the study of and station. Given the small amount of scale, temperature anomalies observed hydrodynamics of lagoon areas, gradu- data available, one is limited to a visual in Europe are clearly part of a global ally allowing the acquisition of greater inspection and a qualitative discussion trend. It is in this sense therefore, that knowledge of dynamics and local vari- of the behaviors. the monitoring campaigns carried out in ability could, at the same time, con- the Po Delta lagoons between 2005 and tribute to improving the quality of the The comparison is shown in Figure 13. 2010 allow for the environmental data monitoring system, by for example, opti- The temperature evolution bears simi- refering to a particularly important pe- mizing the choice of measurement site larities with those of the EA, WP (inverse riod regarding both regional and global position and enabling an approach to correlation) and PNA (inverse correla- climatic conditions, to be made available a preparatory analysis phase for the tion) indexes. Both evolutions of salinity today. development of the capacity to pre - and dissolved oxygen are characterized dict extreme events in the Po Delta by a marked tendency to decrease, but Conclusions lagoons. they nonetheless bear similarities with those of NAO, WP and PNA. The de- Annual water quality monitoring pendencies, which are more or less pro - campaigns have been carried out in the nounced depending on the parameter Po Delta area since 2005. These have in- analyzed, of the local dynamics on those volved a gradually increasing number of at the large-scale suggest that the un- lagoons, bringing it to its current moni- derstanding of the latter, together with toring system made up of six sampling their contextualization within a longer sites: the Scardovari (two measuring time period, is preliminary for assessing sites), Canarin, Basson, Marinetta and whether the data collected for the Delta Vallona. lagoons during the few years so far describe a typical rather than exceptional The temperature, salinity and dis- state. solved oxygen data available today are an important source of information in Figure 14 shows the average winter order to understand the physico-chem- and summer near-surface air tempera- ical and biological property dynamics of ture anomalies for the years 2005-2010 the various lagoons, as well as for their compared to their climatological value effective management. for circa the last 60 years (NCAR Rea- nalysis data). In the European context, This study has shown that much can it is clear that winter temperatures are be observed in the data regarding the considerably above average over Scan- characteristics of the “Delta del Po”

38 Bibliography Kalnay et al., 1996: The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470 Zanchettin, D., Traverso, P., Tomasino, M., 2008. Po River discharge: an initial analysis of a 200-year time series. Clim. Ch., doi: 10.1007/s10584-008-9395-z, Vol 89(3-4), 411-433 Zanchettin, D., A. Rubino, P. Traverso, and M. Tomasino, 2009. Teleconnections force interannual-to- decadal tidal variability in the Lagoon of Venice (northern Adriatic), J. Geophys. Res., 114, D07106, doi:10.1029/2008JD011485

39 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects _STUDIES & RESEARCH SHELLFISHING IN THE PO DELTA LAGOONS, VENETO: SOCIO–ECONOMIC ASPECTS

FRANCESCO DONATI The research investigates the costs able, both over time and space, in terms Professor of Agricultural Policies and Economics and benefits of lagoon vivification ac- of the main physico-chemical and hydro- ELENA FABBRO tivities conducted for various motives logical characteristics: temperature, sa- Università di Udine by the Consorzio di Bonifica Delta Po. linity and oxygen concentration. Estimates are made regarding the benefits of lagoon vivification followed by Their high nutrient load, especially the calculation of the maximum financial with contributions of fresh water of commitment that the producers could the rivers, along with their particular afford to make in relation to partially mode of sedimentation, accumulation covering the said costs. It also investi- and decomposition of organic debris on gates the possibility of expanding the the bottom, favors the occurrence of production base to Tapes in the Sacca dystrophic crisis that, in the summer, is degli Scardovari. This expansion would one of the main sources of habitat dis- be aimed at achieving a sustainable in- turbance. Over the last three years, the come for the workers and increasing lo- Consorzio di Bonifica Delta Po has been cally added value in the Po Delta area. carrying out vivification interventions A major Tapes production area totaling in the lagoon habitats, investing around 240 ha would allow for, according to our € 2-3 million per year. This work has re- estimates, the reaching of both objec- sulted in a discrete conservation and has tives. At the conclusion of the work an also fostered the production of Tapes, analysis of the Polesine Tapes supply despite the absence of specific expan- chain, and operative multifunctionality sion of the production base. of the sector’s fishermen is carried out. Research Objectives Introduction The lagoons, valleys and wetlands in Most of the Italian Adriatic coast is general, as well as being productive aq- characterized by shallow and mostly uaculture environments characterized sandy or sandy-muddy alluvial bottoms. by high biological diversity, are highly The lagoons of the North Adriatic, of unstable, therefore if one cannot ensure which the Venice Lagoon is a typical their continual management, they are example, have origins dating back to bound to be rapidly reduced to their ini- 6,000 years ago when in the post gla- tial conditions. There have always played cial Wurmian age, the sea invaded the home to a wide range of activities (fish- upper Adriatic plains forming its current ing, hunting, agriculture, small-scale coastal structure. In this way all coastal crafts) brought together by a strong de- lagoons, including those of the northern pendence on the environment and func- Adriatic have become aquatic environ- tions that are mutually compatible. ments that are characterized by variable salinity and the fact that they are sepa- In the Po Delta, after centuries of rated from the open sea by sandbars or continuous interventions, a good bal- stretches of land. More specifically, delta ance has been struck as a result of a lagoons, bays formed by large estuaries “physiological” relationship between and coastal wetlands can be considered territory, the naturality of its physi- transition zones between freshwater cal elements, as well as water system habitats and marine environments1. and economic management. This came These characteristics are highly vari- about by establishing a close relation-

40 Figure 1: the study covers both the primary activities (agriculture and ﬁshing) and the effects on the production chain (production, distribution and sales).

41 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

Tapes ﬁshing area Water surface area Production area Actual yield 2006-08 Tapes per lagoon site (ha.) (ha.) (kg/m2) (%) Caleri and Marinetta 1,653.00 423.56 0.72 29% Vallona 703.00 111.36 0.79 8% Scardovari 3,000.00 320.00 1.52 32% Barbamarco 800.00 50.00 3.53 17% Canarin 850.00 50.00 2.99 14% Basson 375.00 0.00 0.00 0% Total Po Delta Veneto Lagoons 7,381.00 854.92 1.23 100% Consorzio Pescatori Polesine Lagoons 5,025.00 320.00 2.06 63%

Table 1: surface areas and Tapes production ship between production activities Territorial Economic Value in the Delta Polesano. (fishing and hunting) and ecological functions - environmental and water In addition to the economic value protection, the latter have so far been generated by the primary activities assured by periodic excavation of ca - (production and fishing), the survey also nals and interventions aimed at safe - examined other sectors, to come up with guarding and controlling emerging or an Added Value estimate for the whole reclaimed sites. Noting the high pro - production chain. The data and consid- duction values and existence of these erations that emerge could therefore be areas thanks to the vivification inter- considered an important starting point ventions, research into the socio-eco - for the assessment of the effects of vari- nomic aspects of the Delta Polesano ous kinds of changes in lagoon environ- wetlands ecosystems was promoted ments, whether attributable to anthro- proposing two main objectives: pogenic causes or not. - to assess the costs and benefits of carried out interventions or possible Clam Farming in Lagoon Habitats interventions in order to preserve and enhance production; Molluscs were among the first aquat- - to estimate, in general, the Eco - ic organisms to undergo systematic ex- nomic Territorial Value of the shell - ploitation. Awareness of their nutritional fishing industry and its production value has led man to develop ways of chain in lagoon habitats. collecting, cultivating and using them. The shellfishing industry is engaged Assessment of Costs and Benefits in the cultivation of edible molluscs including clam, mussel, scallop and oyster The reference areas for the elabora- farming; and could be considered an ex- tion of the model are the lagoons that tensive aquaculture activity, i.e. a form have already been subject to major of farming and/ or assisted production hydraulic interventions by the Consor- based on the use of the trophic resourc- zio di Bonifica Delta Po. The analysis es of natural ecosystems. mainly concerns the Tapes, for which the provision of information useful in In shellfish cultivation, production making decisions regarding produc- varies depending on the environmental tive investment, conservation and ter- characteristics (nutrient content and ritorial development is intended. water exchange speed) and manage-

42 . . .

. .

. . .

. . . of productive surface area (kg) (kg) area surface productive of 2 . . . per m

Tapes . .

Caleri e Vallona Scardovari Barbamarco Canarin Basson Total Consorzio Marinetta Delta Polesano Pescatori Lagoons Lagoons ment and protection methods set up by year, of which the Venice Lagoon pro- Figure 2: average lagoon yield (in kg their operators. In the northern Adriatic, vides about 47%, the Po Delta in the of Tapes per m2 of the need to ﬁnd appropriate solutions Ferrara area 31%, and the Venetian Po actual surface). for the cultivation of the Philippine clam Delta 20%. In addition these lagoons are emerged in the mid-1980s, when our lo- strategic to the product’s high quality cal clam stock was in danger of running that is appreciated across a large part of out. the target markets.

Clam farming underwent rapid ex- The Po Delta Lagoons: pansion with the introduction of Tapes Surface Area and Production philippinarum2 (the Philippine clam) to the Venice Lagoon in 1983, a species The survey took into account both that quickly spread to most of the Up- the total water surface area of the la- per Adriatic lagoons (Venice, Marano, goons and those actually used for pro- Caleri and the Po Delta). Today, Italy is ductive purposes. Altogether there are the leading European clam producing 7,381 hectares of water surface areas, country and its domestic production of which 11.6% (854.92 ha) are actually amounts to 10,500 tons of Tapes per used for Tapes production.

100,000 Total Consorzio production Sacca Scardovari production 92,378 90,000

80,000 76,630 72,376 68,747 70,000 65,109 60,000 56,142 50,628 46,980 50,000 49,148 41 ,749 41,861 38,632 40,620 40,000 35,796 Produttiva (qli) Produttiva 33,313 40,172 36,011 Figure 3: Tapes 34,493 30,733 30,000 Production (ql) 30,515 32,951 28,433 26,476 25,409 pertaining to 20,000 the Consorzio di 13,668 14,655 Scardovari between 10,000 11,739 2000-2008 0 (R. Rossi, University 2000 2001 2002 2003 2004 2005 2006 2007 2008 of Ferrara).

43 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

The incidence of the production ar- unreliability, but also because of the The Consorzio di Bonifica, through eas in the total area of the lagoons (Ta- criterion assumed in the definition ef- systematic lagoon vivification interven- ble 1) goes from zero in the Basson to fectively productive area. In particular, tions, contributed in improving the situ- a maximum of 29% in northern areas the percentage of productive surface ation in these lagoons. At the moment, (Caleri and Marinetta). In particular, area is high in the Caleri and Marinetta in addition to a systematic vivification with an average of 6.4%, the level of in- and the south Vallona areas (25.6% plan, fishermen and local communi- cidence is relatively low in the lagoons and 15.8% respectively), whereas, in ties are also hoping for development managed by the Consorzio Pescatori the areas in which the Consorzio Pes- interventions and the expansion of the Polesine, with a maximum of 7.3% in catori cooperatives operate, it drops to production base. The following chart the Scardovari and a minimum of 5.9% 6,4%. illustrates Tapes production trends in in the Sacca del Canarin. the Delta Polesano (2000-2008). Tapes Having said this, one observes that production in the Sacca degli Scardo- Tapes production estimates in the the actual yield per square meter has vari shows less movement than in other lagoons was based on data provided by a maximum value in the Laguna del areas; and this highlights how this la- the fishermen, to which we have added Barbamarco (3.53 kg), followed by the goon is strategically important to the information3, and amounts, for the Sacca del Canarin (2.99 kg), the Sacca entire Po Delta. 2006-2008 period, to 105,176 quintals degli Scardovari (1.52 kg); the Vallona annually: the northern area accounting (0.79 kg) and the Caleri and Marinetta Tapes 5 Sector Manpower for 28.9%, the Vallona 8.4% and areas 0.72 kg. In the Basson lagoon Tapes are pertaining to the Consorzio Pescatori di only fished when there are no adequate The fishermen and / or Tapes farm- Scardovari4 the remaining 62.7%. The operating conditions in the Canarin or ers use small, usually two-man, ves- Consorzio Pescatori di Scardovari’s Barbamarco; the 25 tons of Tapes that sels (barchini6) to carry out their work. production can be subdivided into: are caught annually therein, were divid- At the end of each collection opera- 33,350 quintals of Tapes in Sacca degli ed equally between the quotas of the tion they carry out an initial processing Scardovari, 17,641 quintals in the Lagu - other two lagoons. of the product in dedicated huts or on na del Barbamarco and 14,969 quintals specific platforms. The remaining stag- in the Sacca del Canarin. In recent years the production of es of the production chain: processing Tapes has however undergone substan- and selection, purification, packaging, Remarkably, the Sacca degli Scar- tial fluctuations. The least productive transportation and sales, are carried out dovari, with 320 hectares of cultivated year was 2003 when, according to a downstream. The Consorzio Pescatori land or orti, accounts for approximately study by Prof. Remigio Rossi of the Uni- purifies and processes almost all of its 63% of the Delta Tapes. Moving from versity of Ferrara, only 300 ha of water members’ product at its own Scardovari production totals to unitary yields, one surfaces were judged to be suitable for plants. The Tapes from other areas are has to proceed with caution, not so clams, with the surface area being re- taken to processing centers in Chioggia much because of the productive data’s duced by 50% compared to 1999. or other villages.

Occupants Age group (year) Sex

Total Per area < 30 31 - 45 46 - 60 > 60 Male Female North Area Cooperative 241 13.36% 17.30% 45.30% 30.70% 6.70% 94.20% 5.80% Scardovari cooperative consortium 1,496 82.93% 15.90% 44.10% 33.10% 6.90% 49.20% 50.80% Total cooperatives 1,737 96.29% 16.20% 44.40% 32.50% 6.90% 59.80% 40.20% Private and Vallona 67 3.71% 15.60% 45.00% 32.10% 7.30% 100.0% 0.00% Tapes ﬁshermen totals 1,804 100.0% 16.20% 44.40% 32.50% 6.90% 62.00% 38.00%

Table 2: Tapes ﬁshing-cultivation workers in the Delta Polesano.

44 AREA

FUNCTION Consorzio Pescatori Individual Cooperative (only for the South Area lagoon fishermen) Possession and management of fleet Managed by individual fisherman Manages administration Any information about the optimiza- tion of fleet Tapes seeding Materially carries out the seeding Draw up consultation plans with the Draws up plans for seeding, sees to Consorzio the acquisition of the latter and covers seed costs Tapes fishing Managed by individual fisherman Realize fishing plans Draws up fishing plans in collaboration with the Co-operative Tapes purification and sales - In the North Area lagoons and for Direct transformation and purifica- private entities, functions are carried tion operator; sells the finished out by other bodies product within its competence Risk Assumption Production risk and fishing There are apparently no specific risks Assumes the industrial and com- management mercial risks Cultivation fishery management Materially carries out the operation - Provides financial backing and know-how in its areas of competence Technical Support - - Manages technical assistance in its areas of competence

Laboratory - - Managed by the Consorzio in its areas of competence

Table 3: Tapes production chain: functions and competencies.

In late 2009, the Delta Polesano men and 38% women, while in terms farming sector, but that would allow for Tapes sector employment amounted to of age, 50.6% are under 45 years old the initiation of leisure activities and 1,804 units, for 96.29% for the coop- and 16.2% under 30. The percentage for the more efficient conservation and erative associated fishermen and 3.71% of workers over the age of 60 is very management of resources. for employees of private companies. low and is estimated at around 7%. The Regarding the allocation of employees large quantity of youth allows for the hy- The Consorzio di Bonifica, fishing co- in the fishing area, 13.36% work in the pothesizing of both production growth operatives and Parco del Delta’s future Northern Area lagoons, 82.93% in the strategies and territorial development. intervention plans therefore need to find Consorzio Pescatori lagoons (Sacca, In particular, in the Sacca degli Scardo- common moments of synthesis, with a Barbamarco, Canarin e Basson), and vari one could consider multi-purpose view to a productive valorization relat- 3.71 % in the Vallona area. Regarding interventions that could not only ensure ed to the protection of the ecosystem. employee gender distribution, 62% are the further development of the clam One should bear in mind that clam and

Tapes production Tapes GMP Tapes GMP Workers GMP/ Worker GMP/ Worker (2006-2008) (2006-2008) (2006-2008) (n) P=2.4 € / kg P=3.0 € / kg (q) P=2.4 € / kg P= 3.0 € / kg (Millions of €) (Millions of €) Delta polesano 105,175.9 25,242 31,553 1,804 13,992 17,491 Lagoons total

Consorzio Pes- catori Polesine 65,960.0 15,830 19,788 1,496 10,582 13,227 Lagoons total

Table 4: Tapes production and GMP: Delta Polesano Lagoons.

45 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

shellfish cultivation depend on the natu- faster, consume more fuel and conse- ral factor, which should be used in order quently have higher costs. to support natural cycles and production, thus ensuring sustainable econom- The Tapes fishermen carry out their ic production and providing long term fishing activities in the form of sole pro- stable employment. prietorships, while in the other management stages they are associated with Tapes Fishing Systems and cooperatives. The cooperatives plan the Early Stage Production Chain work of the individuals, in order to main- Organization tain a sustainable harvest and contain business and technical risks. The Con- The barchini are generally 40 hp. The sorzio Pescatori di Scardovari is there - Tapes fishing fleet is made up of over a fore a third-level entity that, in addition thousand vessels, while that of the Con- to providing assistance to members (co- sorzio Pescatori cooperatives amounts operatives and individual), is primarily to 700. In recent years, thanks to the concerned with the development and provision of specific contributions, forty marketing of products. The following boats with upgraded engines (110-120 diagram summarizes the various func- hp) were purchased, which although tions performed by the various entities within the Tapes production chain.

16,000 Gross Marketable Production and Production Scenarios

14,000 The Gross Production (GMP) of the primary Tapes sector in the Delta Pole- 12,000 sano for 2006-2008 was estimated at two price levels: - 2.4/kg, which corresponds to 10,000 € the average production price at the end of 2009; resulting in a GMP of 8,000 € 25,242 million; - € 3.0/kg, corresponding to the av-

6,000 erage price over the 2006-2008 period, resulting in GMP of € 31,553 million. estimated to be € 13,992 on average, 3.0/kg ( € / worker) € 3.0/kg NI st Calculating the GMP on two price lev- with a minimum of € 10,582 for Consor- 4,000 els underlines the effects of the crisis in zio Pescatori di Scardovari members. the sector at the time of the survey. This Since we are dealing with revenue and

2,000 crisis could be considered fairly cyclic not income, in order to calculate the lat- and in our opinion, depends on both a ter, one should subtract the production mismatch between supply and demand costs7. These costs were calculated over 0 with an excess product that determines both the short (considering only those Consorzio Delta Po 8 Scardovari Lagoons the low prices of Tapes, and also the in- variables ) and long-term (variable and Lagoons adequate bargaining power of produc- ﬁxed costs). In lieu of the situation at ers in the face of a near oligopoly of dis- the end of 2009, it was decided that the Figure 4: short Term NI (Tapes at tribution. The annual GMP per worker, short-term Net Income (NIst) parameter €3.0/kg). measured at a price of 2.4 € / kg, was would be used as a reference point.

46 Figure 5: mussel farming in the Sacca degli Scardovari.

The average variable costs per em- tegration of at least € 2,500 per year/ calculations were therefore formulated ployee on average for the lagoons worker would be required in order to corresponding to € 3.0/ kg of Tapes. was valued at € 2,873 (€ 2,173 for Con- reach the sustainability threshold. The Short Term NI for the entire Delta sorzio Pescatori Polesine members). Polesano was € 14,617 per year/ work- The Short Term Net Income (NIst) was Calculating the Long-Term Net In- er, with a minimum of € 11,054 in the calculated by subtracting the afore- come again at the end of 2009, one sees lagoons attributable to the Consorzio mentioned costs from the annual GMP a decrease to € 6,000/ worker, a ﬁgure Pescatori. Clam farming exclusively per worker which resulted in a total of that is way too low to ensure the eco- was not enough to ensure a minimum € 11,119/worker, with a minimum of nomic sustainability of the ﬁshermen. of socio-economic sustainability, espe- € 8,409 in the lagoons attributable to Given equal production yield, the sell- cially for the members of the Consorzio the Consorzio Pescatori. Evidently this ing price is hence the most important Pescatori. In order to overcome this cri- was not a sustainable Net Income, and parameter in determining economic sis, partly mitigated by there being two was estimated at the time that an in- and social sustainability conditions. Our workers per every household, develop-

47 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

Figure 6: minor GP G.P. (millions of €) . and minor NI no lagoon viviﬁcation. NI (millions of €) . . . .

. . .

ment solutions had to be found. tion of the lagoon habitats but also to im- soon thereafter, a production regression9 prove Tapes production in the Delta. amounting to a loss of product (Tapes) of During the on-going crisis there has between 10% and 25% in the absence of been an increase in unemployment of The Effects of Hydraulic intervention. This regression would have about 20%, with 400 employees less in Interventions on the Tapes resulted in negative scenarios for pro- just the primary sector. In light of this Industry ducers and for the whole Delta Polesano threat, the individual manufacturers, the economy. It is believed therefore that in Consorzio Pescatori di Scardovari and The hydraulic interventions carried the medium term, only conservation is the Consorzio di Bonifica have intensified out in recent years by the Consorzio di not sufficient to support the economy of efforts to not only promote the vivifica- Bonifica Delta Po have had two main ef- the area, and for this purpose one hopes fects: for interventions aimed at broadening - Maintaining fair sustainability condi- the production base, especially in the Structural Unit of Project data measure- data tions for the fish biomass, Sacca degli Scardovari. ment - Safeguarding Tapes production in Project duration years 10 the lagoons. Conservation or Vivification Employees number 20059 Interventions Average Tapes €/kg 3.5010 A model that investigates the effects price of the absence or lack of hydraulic inter- These allow for production yields to New cultivated ha 240 ventions was then prepared. According to be maintained. In fact, the work carried surfaces our estimates and also in the opinion of out by the Consorzio di Bonifica for hy- Table 5: structural data hypothesis of the project. various experts, there would have been, draulic order (safety) reasons has ben-

. .

% Contribution on RN % Contribution Figure 7: estimate Max contribution ( € /ha)Max contribution of maximum conservation value . of production function per Ha of Regression -10% Regression -15% Regression -20% Regression -25% lagoon.

48 . Figure 8: annual . investments over the . course of the project (in millions of ). Hydraulic Investments € . Fishermen Investments

......

efited the Tapes industry. The costs of come which ranged from a minimum of of € 396.6 /ha (medium-high regression). hydraulic interventions amounted to € 1.748 million per year to a maximum of Private contribution hypothesis were not around € 2.5 million annually and to- € 4.369 million depending on the level compatible with the producers’ disburse- taled € 12.5 million over a five year pe- of regression expected. One should also ment capacity at the time of the survey. riod. In relation to these amounts what consider that in the lagoons, the Tapes It was deemed appropriate to postpone can be defined as the conservation ben- fishermen are also involved in the man- any contributive hypothesis to a later efit is derived from the Tapes, being the agement of collective assets which have date. However, the problem of low profit- primary sector. Our investigation has a positive impact on the community. We ability per worker remained unresolved therefore arrived an estimate of loss of therefore attempted to come up with an at the time. In order to increase profit- product that would be recorded in the approximate value for this environmen- ability one could, in theory renegotiate absence or deficiency of a vivification tal management that we estimated to be the price and contractual power of pro- intervention. This estimate was made a third of the value of the minor income. ducers. according to four levels of possible re- Subtracting the amount attributable to gression: environmental management carried out We consider it opportune therefore to - mild (-10% of the product); by the producers from the minor NI, we direct the producers towards a broaden- - medium - low (-15%); were able to estimate the pure value of ing of the production base that should be - average (-20%); maintaining the function of Tapes pro- compatible with environmental conser- - medium-high (-25%). duction. For the lagoon environments vation as well as the dynamics of Tapes this value corresponds to the net ben- demand. By applying a supply-demand At the price of € 2.4 /kg of Tapes, efit for the private sector in the face of model designed for the domestic Tapes these production regressions would maintenance and hydraulic vivification market, we predicted that the relation- result in a loss of GMP ranging from a interventions. In theory it corresponds ship between supply and demand could minimum of € 2.524 million per year to the maximum level of contribution have normalized within three to five (-10%), up to a maximum of € 6.310 mil- that the Tapes fishermen would be able years. At the end of this period, we fore - lion. A lower GMP also involves reduc- to make, if the price allowed, in order saw the sale of an increased production tion of variable costs so by subtracting to maintain production. On average in of about 15-25%. Veneto Po Delta clam the savings on variable costs from the the Polesine lagoons, this benefit would farming would have been able to claim a minor GMP, we were able to arrive at range from a minimum of € 158.6/ ha of fair quota of the increased demand con- an estimate for the lowest annual in- lagoon (slight regression9),to a maximum sidering the high quality of their product.

49 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

Project years 0 1 2 3 4 5 6 7 8 9 10 Total

Hydraulic works 18.000 - - 3.600 - - - - 3.600 - - 25,200

Maintenance project - 0.900 0.900 0.900 0.900 0.900 0.900 0.900 0.900 0.900 0.900 9.000

Project - 0.180 0.180 0.180 0.180 0.180 0.180 0.180 0.180 0.180 0.180 1.800 overheads

Total 18.000 1.080 1.080 4.680 1.080 1.080 1.080 1.080 4.680 1.080 1.080 36.000 Consorzio Delta Po

Barchini investment 2.880 - - - - 2.880 - - - 2.880 - -

Engine investment 1.920 - - - - 1.920 - - - 1.920 - -

Hut investment 0.750 ------

Total 5.550 - - - - 4.800 - - - 4.800 - 15.150 ﬁshermen investment

Fuel (+40%) - 1.615 1.615 1.615 1.615 1.615 1.615 1.615 1.615 1.615 1.615 16.151

Barchini maintenance - 0.366 0.366 0.366 0.366 0.366 0.366 0.366 0.366 0.366 0.366 3.655

Hut maintenance - - - - - 0,150 - - - - - 0.150

Other private costs - 0.167 0.167 0.167 0.167 0.167 0.167 0.167 0.167 0.167 0.167 1.665

Total private 0.000 2.147 2.147 2.147 2.147 2.147 2.147 2.147 2.147 2.147 2.147 21.622 management costs

Total 23.550 3.227 3.227 6.827 3.227 8.177 3.227 3.227 6.827 8.027 3.227 72.772 project costs

Fishermen income - 5.013 5.013 5.013 5.013 5.013 5.013 5.013 5.013 5.013 5.013 50.125 Integration (€2,500/ year per employee)

Total 23.550 8.240 8.240 11.840 8.240 13.190 8.240 8.240 11.840 13.040 8.240 cash ﬂow to deduct

Revenue from 0.000 4.200 6.300 12.600 12.600 12.600 12.600 12.600 12.600 12.600 12.600 111.300 project development

Public intervention 11.700 - - 2.340 - - - - 2.340 - - 16.380 in hydraulic works

Total 11.700 4.200 6.300 14.940 12.600 12.600 12.600 12.600 14.940 12.600 12.600 127.680 active cash ﬂow

NPV i= 0% -11.850 -4.040 -1.940 3.100 4.360 -0.590 4.360 4.360 3.100 -0.440 4.360 4.783

NPV i= 4.1% - IRR -11.850 -3.879 -1.789 2.745 3.708 -0.481 3.419 3.283 2.242 0.305 2.907 0.000 =4.136%

Table 6: project cost-beneﬁt analysis (in millions of €) the higher market price.

V.A. P.L. totale P.L. polesano % V. A. totale V.A. polesano % extra polesano (ML di € ) ML di € P.L. polesano (ML di €) ML di € V.A. polesano (ML di €) Primary Tapes 25.242 25.242 100% 20.194 20.194 0 100% Secondary Tapes 12.095 9.07 75% 7.256 5.441 1.815 75% Primary + 37.337 34.312 92% 27.449 25.634 1.815 93% secondary Tapes Tapes terziario 10.518 2.104 20% 5.259 1.052 4.207 20% Tapes ﬁliera 47.855 36.415 76% 32.708 26.686 6.022 82%

Table 7: GP and AV at a price of € 2.4/kg in the three production sectors15.

50 Figure 9: the fishermen and/ Productive Development come; or Tapes farmers use small, usually Interventions - The co-financing of the investment two-man vessels by the fishermen. (barchini) to carry out their work. In order to plan the expansion of the production base, the Polesano district The Short Term NI per worker was Tapes production chain was analyzed, of calculated to be € 11,119 per year. With which the key elements are summarized the increase of the production area (240 below. hectares), with an average yield of 1.5 kg/ m2 of Tapes, we estimate an increased The Primary Sector annual production of 3,600,000 kg of Tapes, which would raise the annual NI to 63% of the Delta Polesano Tapes per- € 2,500 /per worker, a figure that would tains to the plants of the Consorzio Pes- meet the desired objective of sustainable catori del Polesine. In the area where this NI. According to our hypothesis, however, Consorzio does not work, Tapes are puri- a public intervention amounting to 65% fied outside of the area, or sold to trad- of the costs of hydraulic works would be Tapes to traders is well-established, one ers who carry out these operations in required. As can been seen from the ta- could continue to work in this way, and appropriate places. The expansion of the ble below, the project would require, over new facilities to cope with the planned in- production base requires both hydraulic a ten year period, the hydraulic invest- crease in production would not be need- interventions carried out by Consorzio ment of € 36.0 million. The investment ed. Since it is assumed that the interven- di Bonifica as well as the investment of in barchini, huts and other fishing equip- tions relate to the lagoons attributable to private fishermen (barchini, huts, fish- ment however, would amount to € 15.15 the Consorzio Pescatori, this consortium ing equipment etc.) In the face of these million over the same period. has three possible solutions: interventions estimates for additional - sell surplus product before processing; flow of Tapes products and related costs The Secondary Sector - process the new Tapes at the Scar- have been made. Our design hypothesis dovari facilities, without having to expand is based on two assumptions: In areas where the Consorzio Pesca- structurally; - an increase in the workers’ Net In- tori operates, and where the selling of - expand existing facilities.

51 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

In the first case one does not foresee Tapes production of up to about 30%. project are shown below. A cost-benefit any problems in particular, except for analysis was prepared using the above the loss of some territorial added value; Regarding the need to expand the data and by taking design hypothesis in the second case there could be econo- network of business services, the as- developed by sector technicians into mies of scale as fixed costs decrease per sessment is a bit broader: these are account (Table 6), which highlights how kilogram of product and in the third, the services that must be organized based the project will be able to repay, over Consorzio Pescatori would have to face on the district. It is therefore considered an economic period of one decade, investments of an industrial nature, ac- appropriate to invest in research, tech- both hydraulic as well as private invest- quiring new technology and optimizing nical assistance and monitoring (human ments, hypothesizing however, that the organization. capital rather than equipment), invest- community takes on 65% of the cost of ments that would not only help the new water projects. The internal rate of re- The Tertiary Sector production, but that would also valorize turn (IRR), the net of this contribution, the current one. taking into account the integration of This sector is divided into transport, income guaranteed to the fishermen, marketing and business services. Re- In order to quantify the costs re- would result in an average price of garding transport, there should not be ferred to in the previous graph, we made € 3.5/kg of Tapes, equal to 4.1%12. In ad- any major difficulties, as there are sever- use of information collected from key dition to the benefits of the project, the al companies that are well equipped on a players in the Polesana Tapes produc - fishermen, while exposing themselves national level that are able to deal with tion chain. The cost-benefit model that to greater technical and management production increases, like that which has follows was prepared in a flexible way, risks, could also take advantage of a been hypothesized, without any prob- in order to change certain elements surplus of income owing to. lems. Regarding the marketing, be it while maintaining other values. Differ- after the fishing phase or after the pro- ent trickle down effects such as work- The Polesine Shellfish cessing of the product (as in the case of ers’ income, the sustainable workforce Production Chain the Consorzio Pescatori), one can make and the expected internal rate of return a similar argument: the Polesine and / or (IRR) can be assessed, on equal terms, The following paragraph presents lower Veneto operators would have no via discontinuous simulations. The prin- the Gross Product (GP) and the Added problems in dealing with an increase in cipal structural data of the development Value (AV)13 of the Po Delta Tapes pro -

BENEFITS TO THE PRIVATE SOCIAL BENEFITS ENVIRONMENTAL BENEFITS Increased income in the primary sector; better Employment stability in the Delta polesano Natural Resources Conservation in synergy living conditions for fishermen with lagoon production areas Improved management security for the Con- Qualification of human capital in the shellfishing - sorzi Pescatori sector Economic benefits for the shellfish processing More employment - enterprises Economic benefits for companies that provide Employment stability - the fishermen with productive means

Economic benefits for service companies Employment stability - (transportation companies, the Consorzio’s various purifiers, distribution companies) Economic benefits for associated businesses Social capital; development of service activities - (technical assistance, credit) related to the production chain. Benefits for tourism operators and catering Development of environmental tourism; develop- Greater awareness of and attention paid to ment of culinary tourism environmental values Returns on a general local level and support for Improved perception of the image of the Delta Valorization of the Delta Polesano lagoons as multifunctionalism region ecological and productive entities

Table 8: returns on the Tapes production chain.

52 duction chain, broken down into its three sectors. The primary sector’s GP is estimated to be € 25,242,000 at a price of € 2.4 /kg14, and € 36,812,000 at € 3.5 /kg. The secondary sector’s GP is calculated from the management budget of a facility that processes and sells shellﬁsh wholesale; at this stage of the production chain, from the bagged product on the dock to when it is loaded onto ve- hicles, there is a unit cost of € 0.50 to € 0.60/ kg for puriﬁed Tapes and € 1.0- € 1.3/ kg for those already bagged.

Since the Delta Polesano produces 10,517.6 tons of Tapes annually, the GP of the secondary sector is estimated at € 12.095 million. The GP aggregate (primary plus secondary sector) thus amounts to € 37.337 million while it would rise to € 48.907 million fetching an average price of € 3.5/kg.

The GP of the distribution sector located immediately downstream of the processing is estimated to be on average € 1.0/kg of Tapes, and still does not include the last distribution link (large- scale retail channels, ﬁsh shops and other outlets). Applying this unit value to the amount of Tapes involved in the ﬁrst marketing stage, one estimates a tertiary sector GP of € 10.518 million.

For the entire Polesine Tapes production chain, the GP is € 47.855 million, and rises to € 59.425 when fetching a price of € 3.5/kg. The Added Value (AV) was then calculated, which for Tapes at € 2.4 /kg, amounts to € 20.194 million in the primary sector, € 7.256 million in the secondary and € 5.259 million in the tertiary sector. Summing up the three

Figure 10: the processing and preparation of shellﬁsh for sale.

53 The Po Delta Lagoons October 2013

Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

Figure 11: the Figure 12: through processing stage. co-operatives and the consequent planning of the individuals’ work, one can ensure the sustainable harvesting of shellﬁsh.

sectors one arrives at an AV of € 32.708 sector, would generate a higher income timates, the 1804 workers had 1,269 mul- million which would rise, with an average in the primary sector, higher employment tifunctional positions. The biggest group, price of € 3.5/kg, up to € 41.965 million, in the manufacturing sector (20-25 new with 949 people, was that of the fishing an increase of 28% compared to 2009. units16), in addition to considerable so- activities (mussel, small internal fishing cial benefits. In the Delta municipalities fisheries and marine fishing). In Table 7 one can see the GP and AV involved in the Tapes production chain, of the Polesine Tapes production chain these effects combine to significantly im- One could then synthesize that Tapes for 2009. In addition, in the same table, prove social stability. One could add that fishing plays an important role in ensur- one can see the Tapes’ territorial value or the economic benefits of the privates, of ing the survival of ancient water trades, that which lies with the operators and the a social and environmental nature, have while the integration of income from companies in the Polesine. A further con- no clearly defined boundaries. traditional fishing and mussel farming sideration regards the possible econom- proves decisive for the economic sustain- ics of the production chain. It is foresee- The development and conservation ability of the calm fishermen, crucial in able that bigger production will reduce projects, as well as involving a large part these times of crisis. On the other hand, unit costs in the processing section. For of the Po community either directly and traditional fishing’s low income would example, if this section were expanded at indirectly, are strategically important condemn this activity to all but disap- Scardovari, there would be an estimated for the lower Veneto area, and one could pear, if it were not for clam fishing. Put- average unit cost for the new immobiliza- conclude that the benefits to the fisher- ting together all the trades in whichever tion of € 0.50/kg of product, compared men, businesses and communities of the way the Tapes fishermen are employed, to € 0.66/kg for having created installa- Delta fully justify the assumed costs of one arrives at 70% for secondary operations from scratch, this shows a discrete public intervention. The final diagram tive positions, a figure that also highlights advantage in investing in the present lo- shows the possible effects related to the working flexibility of the Delta fisher- cation. these interventions. Another fact that men. Thanks to this multi-functionalism emerges from the research is the high they are able to protect trades that would The Socio-Economic Impact of level of compatibility between the clam otherwise no longer survive on their own. the Delta Polesano Tapes and other activities of the primary sec- It is also for this reason that the lagoon tor. Tapes fishermen also often carry out, vivification interventions provide essen- The proposed works, for both lagoon to a lesser degree, other activities. At tial social benefits to the sustainable de- conservation and expansion of the Tapes the time of survey, according to our es- velopment of the area.

54 1 (Barnes, 1980; Knox, 1986 Odum, 1988). 2 An Asian species already introduced along the American coasts between 1930 and 1940 and later introduced to Europe in the 1970s. 3 Our estimate data are slightly lower than those provided by Turolla (Eduardo Turolla – L’allevamento della Vongola verace nel delta del Po, Istituto Delta Ecologia Applicata, Ferrara, 2008). In our survey, the Tapes production total was obtained by adding the actual data of the Consorzio Pescatori (the average conferral in the period 2006-2008), the estimated data in the Caleri-Marinetta areas and that of the Vallona lagoon. The latter were also collected during a previous survey conducted in collaboration with Prof. R. Rossi of the University of Ferrara, during the filiera ittica polesana project. In order to go back to the Caleri and Vallona’s current production data, an average expansion coefficient was applied to the previous data, which took into account the average increase that occurred over the area. 4 On a national level, the Consorzio Pescatori accounts for approximately 13% of the total production volume. 5Table 2 includes manpower data up to the end of 2009. They do not include the 200 Delta fishermen/women that had already applied for Tapes fishing permits, including about 60 women registered with the Cooperative. 6 barchini: a term used by fishermen to refer to small motorboats. 7 These costs were calculated according to “standard boats” operating 250 days a year with a crew of two. 8 The variable costs are those that vary with the production and, in theory, amount to zero when production ceases. For the barchini, fuel and maintenance costs of both engines and hulls fall under variable costs. They are fixed management costs that do not depend directly on production volume (deprecia - tion, overheads and insurance). The cost of labor is not included because it makes up part of the operators’ Net Income (NI) together with the interest on capital and eventual profits. 9 By production regression one means a lower annual production of Tapes that is calculated in this report in relation to the average over the years 2006- 2008. 10 In late 2009, there were 1805 workers; the 200 workers waiting to enter the sector were taken into account in the project predictions. 11 Average expected Tapes price, based on recent prices (2011-2012) and market forecasts. 12 Rate of return one supposes is approximately equal to the price of money should the fishermen file for facilitated bank loans. 13 Albeit in an improper manner, the term added value denotes the total of remuneration relating to labor, capital and management, before amortization of capital projects and taxes. 14 Price at the time of the survey (end of 2009). 15 In this case the primary sector is calculated using the GMP instead of the Added Value; a methodological adaptation that does not affect the validity of the analysis model proposed however. 16 The additional investment would result in 20-25 new employees in the secondary sector, with an average immobilization of around € 100,000/employee, a fairly low amount since our hypothesis would benefit from economies of scale and the relationship with the already existing Scardovari plant.

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Shellﬁshing in the Po Delta lagoons, Veneto: socio–economic aspects

Bibliography A.P.I. (2003): Acquacoltura A.P.I. informa, Anno XVII, n°11. AA.VV., (2005). La filiera della vongola Tapes philippinarum in Italia. A cura di Boatto V., Pellizzato M., Milano, Franco Angeli Ed., 185 pp. AA.VV., (1990). Tapes philippinarum. Biologia e sperimentazione. Regione del Veneto, ESAV, 299 pp. Boatto V., Silvestri S., Rossetto L. (2005). Analisi economica della filiera di Tapes philippinarum, in: Boatto V., Pellizzato M. (a cura di), La filiera della vongola, Milano, Franco Angeli Ed., 185 pp. Cesari P., Pellizzato M. 1985 – Molluschi pervenuti in Laguna di Venezia per apporti antropici volontari o casuali. Acclimazione di Saccostrea commercialis (IREDALE & ROUGHELY, 1933) e di Tapes philippinarum (ADAMS & REEVE, 1850). Boll. Malacologico, 21(10-12):237-274. Donati F., Vasciaveo M., Zoppelletto M., (1998), Environmental and multi-functional management of lagoons and coastal wetlands, Aquaculture and water: fish culture, shellfish culture and water usage, Atti Conferenza Internazionale Aquaculture Europe, Bordeaux 1998, European Aquaculture Society, Special Publication no. 26, 1998 Donati F., Vasciaveo M., 1998, Sistemi per la gestione integrata degli ambienti lagunari e vallivi, Volu- me Atti Conferenza: “Le ricerche sulla pesca e sull’acquacoltura nell’ambito della legge 41/82”, Roma, 1998, Vol. 5, fasc. 3. Donati F.,Agostini P., Costi e benefici della vallicoltura in Italia, Il pesce, n. 1/1992. Donati F., valutazione delle funzioni economiche nelle valli da pesca, Genio Rurale, n. 5/1992 ICRAM (1994): Guida pratica di mitilicoltura. Ed. ICRAM. ICRAM (2004): Pesca ed ambiente in laguna di Venezia e nell’Alto Adriatico. Ed. Il Leggio, Chioggia. Ismea (2002): Elaborazione su dati API ICRAM. Filiera Acquacoltura, Roma. Ismea (2005), Filiera pesca e acquacoltura – Roma Ismea (2006), Il settore ittico in Italia e nel mondo: tendenze recenti, Roma Ismea (2007), Il settore ittico in Italia e nel mondo: tendenze recenti, Roma Ismea (2007), Outlook dell’agroalimentare italiano –Rapporto annuale– Indicatori del sistema agroalimentare italiano volumi I e II, Roma Mipaf (2005), Azione di monitoraggio delle produzioni ittiche dell’acquacoltura Italiana (reg. CE N°1263/99 e 2792/99 SFOP) – seconda relazione intermedia anno 2003 Paesanti F., Pellizzato M., 2000. Tapes philippinarum. Manuale di divulgazione. Serie acquacoltura. Padova, Veneto Agricoltura, 2ª Ed., 74 pp. Prioli G. (2000): Censimento nazionale sulla molluschicoltura. Consorzio UNIMAR. Quaderni Provincia di Venezia, 2000. Piano per la gestione delle risorse alieutiche delle lagune della Provincia di Venezia. Benevento, Sannioprint Ed., 102 pp. Rossi R., (1996). Allevamento di vongola verace filippina (Tapes philippinarum): gestione della semina e del trasferimento in campo naturale per la ottimizzazione del raccolto. Ministero delle Politiche Agricole. III Piano Triennale (DM 04/92 del 18.02.1993) Rossi R., (2000). Elementi di valutazione ecologica, economica e sociale per fronteggiare la flessione produttiva di vongole filippine nellÁlto Adriatico. Ricerca 5C02, V Piano Triennale. Rossi R., 2000. Gestione produttiva della Sacca di Goro (Delta del Po): analisi dei parametri ambien - tali, biologici e socioeconomici per la valutazione del regime concessorio. Ricerca 5C04, V Piano Triennale. Spencer E.E., 2005. World shellfish production keeps growing. Fish Farming International, 32 (1):38. Turolla E., 2008. L’allevamento della vongola verace nel Delta del Po. Grafiche Adriatica, 96 pp. Uni - versità di Trieste – Dipartimento di Biologia, 2005. Identificazione di linee guida per lo sviluppo di forme di acquacoltura responsabile ed ecocompatibile di Tapes philippinarum (ADAMS & REEVE , 1850) nelle lagune dell’Alto Adriatico. Ricerca 6-C-70. Ministero per le Politiche Agricole e Forestali. Relazione finale.

56 Figure 13: shellﬁsh in the Sacca degli UILA (2006), Un nuovo futuro per la pesca italiana. Serve innovare per ridurre i consumi, ciclostilato Scardovari. presentazione ricerca curata da Cres e Osservatorio nazionale della pesca, Giulianova Lido (Te), 31 ottobre 2006. Regolamento (CE) n. 708/2007 del Consiglio dell’11 giugno 2007, relativo all’impiego in acquacoltura di specie esotiche e di specie localmente assenti. Zentilin A., Corso G. I., Zanutti G., Pelusi P., Orel G., 2003. Criteri per attività di pesca ed allevamento sostenibili nella laguna di Marano e Grado (UD). I Quaderni di Venzone per l’Europa “La pianiﬁcazione territoriale di un’area S.i.c.: verso i piani di gestione e conservazione”, Venzone (UD), 18 gennaio 2003, 12 pp.

57 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari _STUDIES & RESEARCH ELEMENTS OF ENVIRONMENTAL ENGINEERING IN THE STABILIZATION OF THE SACCA SCARDOVARI

ANDREA BONOMETTO The stabilization of the sandbar that tieth century the lagoon was character- Environmental Engineer closes the Sacca Scardovari is a prior- ized by a planimetric configuration that LORENZO BONOMETTO ity in the Consorzio di Bonifica Delta corresponds to its current perimeter. If President of the Società Veneziana Po’s vivification of the Sacca, within the however, the margins of the basin, with di Scienze Naturali broader context of the overall mainte- the exception of some areas on the west- PIPPO GIANONI1 nance of the lagoons. This article is a ern side, are the same as those today, IUAV Venezia Professor and Dionea Sa and Terra srl Environmental Engineer summary of the research proposals and the internal morphology is substantially operational evolution of the sandbar and different, being characterized in the past the possible integration project involving by vast emerged areas along the edges hydrodynamic, environmental and man- that today have entirely disappeared, agement aspects aimed at, in particular, and by bottoms with a lot more structure the requalification thereof, based on our than the current ones. The conformation knowledge of the dynamics character- of the current sandbars separating the izing similar coastal systems (Gianoni et lagoon from the sea has also changed al., 2010). profoundly, having undergone considerable changes over the years and gradually The Sacca di Scardovari and its withdrawing over time. From the exami- sandbar nation of historical maps, it is clear how, as of the early 1950s, the location, shape The Sacca Scardovari sandbar owes and size of Scanno del Palo have been its current shape to the ebb of dredged subject to constant changes, indices of sediments and proposes once again, in conditions of instability and dynamics the innermost position, the pre-existing subject to, on the one hand, seasonal Scanno del Palo, a peninsula jutting out changes and annual storms, and on the from the coast to the north-east (known other to the changing intensity of river as Punta Barricata). It is for this reason and coastal sediment transport. that in this paper the name “Scanno del Palo” is used when referring to the previ- The combined action of subsidence, ous situation, and Scanno di Sacca Scar- violent storms, and defensive interven- dovari when referring to the geography tions by several different entities, as that followed the ebb that gave rise to well as coastal erosion phenomena are the current state. factors behind the important dynamics that have fundamentally changed the Figure 1: the The genesis of the Scanno del Palo sandbar over the last few decades, with evolution of the Sacca degli goes back to the end of the twentieth a gradual pulling back in recent years Scardovari sandbar century when, due the rapid advance towards a configuration closer to that of (Photo: Consorzio Bonifica Delta Po). southwards of Po di Tolle and Po di Gnoc- the late twentieth century, mainly due ca mouths, a second outer basin (Sacca to interventions being carried out by di Bottonera) that was hydraulically the Consorzio Delta Po Adige which, on connected to the Sacca di Scardovari the one hand, were aimed at reconstruc- 1 Andrea Bonometto: responsible for geo-mor- formed, thus creating a single lagoon. tion via beach nourishment of a sandbar phological and environmental engineering; Lorenzo Bonometto: responsible for ecosystems similar to the preexisting Palo sandbar, and wildlife; Pippo Gianoni: responsible for the The southward advance of the mouths and on the other hand, at maintaining coordination of methodological systems and ecosystems. This work also called on the exper- of these Po distributaries came to an end the efficiency the Southern Mouth in its tise Eng. Bruno Matticchio, who collaborated around 1900, mainly due to the combined current position by means of periodic in the study of the morphological and hydro- effects of subsidence and the lessening dredging and moving of sand (Mattic- dynamic aspects as described in Issue 0 of the Quaderno Cà Vendramin (Matticchio, 2009). of river sediment. For most of the twen- chio, 2009).

58 OCTOBER 2002

DECEMBER 2004

OCTOBER 2006

AUGUST 2008

JUNE 2010

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

Figure 2a: beached logs and tufts of In general, within the changes taking causing strong points of discontinuity Spartina juncea place, erosion phenomena outweighs with major risks to the stability of the aligning the shoreline (Photo L. deposit phenomena which overall, ap- front of the sandbar; Bonometto, 2009). pears to be weakening, with very different trends at the two mouths and areas - along the coastline around the in front of the sandbar: Southern Mouth something very different seems to be happening, there is a - in the north one observes significant clear westward migration of the axis of zone lagunari dell’Adriatico settentrion- lowering of the bottoms in the section be- the mouth channel with material being ale (EEC Regulation 2088/85)”, initiated tween the mouth of the Po di Tolle (Punta deposited. This evolution is also related a series of interventions aimed at stabi- Barricata) and the Northern Mouth, likely to the dredging carried out by the Con- lizing the sandbar and the vivification of due to a lack of sediment discharge in sorzio, which limits the tendency of the the lagoons. In 1997 an intervention was turn primarily due to reduced flow (and channel to move towards the southern carried out to open the new northern thus also solid transport) compared to sandbar and emerged land of the Punta mouth, consisting of the partial dredging the past, from the southern distributary del Polesine, creating a dynamic equilib- of channels branching off from it and the of the Po di Tolle (mouth of Punta Bar- rium point to guarantee the maintenance realization of an intertidal emerged em- ricata); of the southern mouth’s efficiency favor- bankment (labeled, improperly, as a “salt ing the circulation of tidal currents. marsh”) in the central part of the Sacca. - in front of the sandbar’s line of de- Then in 2003, the Consorzio carried out fense, where the bottoms are charac- The “Progetto Generale di sistemazi- the restoration and stabilization of the terized by a system of bars, recent ba- one idraulica e di risanamento idro- Scanno through the realization of a de- thymetric surveys indicate how the bars geologico della Sacca degli Scardovari” fensive reef on its sea facing side, and migrate with remarkable speed, whilst prepared in 1994 by the Consorzio di Bon- a filtering structure on its lagoon facing maintaining fairly stable overall bottom ifica Delta Po Adige as part of the “Pro- side (recently reinforced, again with reef quotas of about 2.5 to - 3.0 a.s.l., but gramma integrato mediterraneo per le elements), filling in the areas between

60 Figure 2b: artificial sandy embankment these elements with the material from mouth, showed how the inclusion of characterized the dredging of the lagoon. solid works, even more so in an area as by abnormal vegetation (Photo L. complex and active as that of the Delta, Bonometto, 2009). These interventions are in their final can trigger rapid evolutionary process- stages, as shown in Figure 1. The inter - es both constructive and destructive, ventions for the reconstruction and associated with the intense transport stabilization of the sandbar in the new dynamics along the coast. It is for this location between two existing outlets reason that future sea defense inter - bilization of emerged areas through en- to the sea are of primary importance ventions must be adequately identi- vironmental engineering works; and the in maintaining the separation of lagoon fied and designed, based on an overall management of periodic maintenance and marine environments and the cir- evaluation of the affected system, and and dredging activities in the channels culation of tidal currents necessary must be preferably accompanied by ex- and mouths, sources of sediment to be for the vivification of the lagoons; a perimental pilot interventions followed managed in an increasingly differenti- condition that is also indispensable to by appropriate monitoring programs in ated way, and designed to be sources of the productivity of the fisheries. The order to assess effectiveness in com- enrichment for beach nourishment ac- eventual elimination or significant re- parison with the expected results and tions and processes. duction of the sandbar would lead to a possible negative impacts on adjacent radical transformation of the Sacca’s coastal waters. The sandbar was conceived in the lagoon system, affecting the Sacca del- 1980s as an artificial functional struc- la Bottonera in particular, that would On the other hand, it is likely that the ture created as part of a lagoon vivifi- become part of the sea. The changes maintenance of the sandbar’s configura- cation project, with multifunctional re- to the coastline’s structure carried out tion, including the two mouths is, in any percussions (primarily environmental, in the past, both the stabilization of case, dependent on two factors over economic, productive, and natural). As the sandbar in the late 1980s and its time: the completion of construction such it is necessary that its manage- division in order to open the northern works to the sandbar, including the sta- ment ensures sufficient spatial stability

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

through periodic maintenance (if not, is similar to the natural characteristics vegetation. there is the risk of losing the sandbar of the coastal environments of the Delta. resulting in the alteration of the whole It should also be noted that the Adri- lagoon system). The management of this Environmental specificity and atic’s high sandy coastlines show, on environment should, where possible, be morphogenetic dynamics the whole, certain peculiarities due to integrated with the natural forces and their geographic position. The location dynamics of the whole system, thereby A specificity of primary importance, of a narrow and shallow stretch of sea reducing the workload and maintenance a direct consequence of the origin of the to the north, along a coastline affected expenses while accentuating the self- sandbar, can be noted in the geo-pedolog- by the cooling and sweetening effects conservation capacity similar to that ical characteristics, significantly different of river water, implicates an attenuation of analogous natural systems. This ap- to those of natural sandbars and beaches. of Mediterranean characteristics, with proach requires in-depth knowledge for Unlike natural ones, formed by the accu- the absence of, among other things, cer- the monitoring of often non-linear evo- mulation of sand selected and classed by tain typical plant species as opposed to lutionary processes and the taking on marine and wind energy, the Sacca Scar- those found elsewhere along the Italian of a flexible maintenance concept that dovari sandbar presents heterogeneous coast; in contrast, similar to other Medi- is able to be continuously adapted de- sediment with very diverse grain sizes terranean coasts and contrary to what pending on the situation. and sand, shells and clayey-silty elements one sees along the European Atlantic in different layers resulting from the qual- coast, the prolonged summer drought The current state of the Scanno ity and inflow localization of materials at that characterizes our climate means di Scardovari2 various stages. Only in the areas that have that the relationship between vegetation been flattened and reshaped by wave and and soil moisture requires, in order to get The current characteristics of the wind action does the sandbar show, at through critical periods, deeper connec- Scanno are the result of evolutionary least on its top layer, sediments that are tions between vegetation and dune sand, phenomena induced by human interven- partially selected, with notable differ- held firm by their root systems and, as in tions (dredging, ebb tide and some re- ences between the sea facing surfaces, the case of Ammophila, by the capillary modeling) and spontaneous processes. in which the maritime climatic energies action of moisture in the groups of bur- The result is a complex of heterogene- produce profound and rapid remodeling ied trunks (Bonometto, 1992), leading to ous environments in which, starting with effects by selecting grain size and favor- evident technical implications. far from natural conditions, spontane- ing the triggering of morphogenetic pro- ous processes tending towards typical cesses best suited to the site, and those It should also be noted that the Vene- beaches environment features progress- on the lagoon facing side, where the en- to coastline’s geographical location, being in several places at different times ergies have a lesser effect on the depth ing in a transitional area between the and speeds, and also over larger areas, of the fills and show more modest results. nearby Alps, the Mediterranean and the have been triggered. The Scanno while gates of Eastern Europe, results in fur- remaining mostly by its very origin, a A direct consequence of this can be ther floral and faunal peculiarity and, in “secondary” habitat with abnormalities seen in the abnormalities of the veg- a eco-mosaic where, in addition to some in its faunal population and vegetation etation compared with the well-recorded endemic species, there are species that cover, dynamics and geomorphology, al- succession of their own natural sand- merge together from the continental and ready has some natural habitats of inter- bars (see for example: Gehu et al., 1984; Asian steppes, alpine and Mediterranean est and shows enough potential for the Fiorentin R., 2007), with the presence of species for which our dunes make up the system to be brought to a structure that ruderal and nitrophilous species and in- geographical limits of their distribution terior populations that differ from those patterns (Bonometto, 1992; Fiorentin R., in the dunes. Abnormalities that have 2007a, b). This particular and wide diver- 2This work is mainly based on a study carried out spanning the years 2009-2010. Some characte- important implications on stability, since sity in a multi level ecotonal system is an ristics of the sandbar have undergone subse - coastal dune resistance and resilience are essential point of reference when evalu- quent further evolution due to natural dynamics secured by the peculiar relationship be- ating the project direction, the current and ebb flow with some modifications compared to the period of investigation. tween the habitat’s geomorphology and state and dynamics of our dune habitats.

62 The sandbars’ sediment/ vegetation analysis of recent morphological sur- to some extent, its “lagoon” character of abnormalities and the simultaneous oc- veys carried out on the Delta coastlines the sea facing side, possibly connected currence of positive dynamics cause (Regione del Veneto 2009), one can see to the inner most position compared to large differences to arise, so much so how the sandbars require, as a guideline, the preexisting “Scanno del Palo”, and that, as a result of several factors, one a depth of about 300-350 m in order to of an offshore protective reef running can currently see heterogeneous sectors. have stable structures hosting adequate parallel to the coastline. One of the ef- These include: the different sediment ecological successions. Due to the sand- fects of this was seen in unusual autumn characteristics due, in different stretch- bar’s limited depth, together with the populations of Spartina juncea (Figure es, to prior ebb flow; the quotas, profiles sedimentological and morphological 2a, left) in the zone that tides and waves and depth of the fills realized; the conse- abnormalities, affects the possible de- usually reach, having a visible stabilizing quent diversity in spontaneously estab- velopment towards the inside of typi- effect on the sands. lished vegetation structure; the locations cal coastal ecological successions and of marine weather and tidal events; quo- hence the formation of mature stabilized The zone corresponding to the em- tas and locations of ebb flow in progress; dune habitats. Along the natural sandy bryonic dunes on the sandbar only shows different sediment redistribution due to coastlines, proceeding from the sea and initial formations, with spread out Cakile spontaneously arising dynamics; the re- moving inland, one finds a typical series maritima populations accompanied to cent re-modeling, protection and system of increasingly mature habitat groups, the south-west by more strips of Sparti- interventions; the effects caused by the from the shoreline to the embryonic na juncea, sparse Agropyron junceum (= adjacent shore. dunes and the first real groups of dunes, Elymus farctus) and halophilic species, to those situated in the internal areas with Inula chrithmoides being particu- The features mentioned above are that are stabilized and interspersed with larly frequent. In the zone correspond- also behind specific critical issues re- fairly wet lowlands. This succession can ing to the first barrier of dunes, there is garding the wildlife. The large surface be seen in a very partial and abnormal an absence of spontaneous formation, areas of artificial origin are a favorite way in the Scardovari sandbar, there are seeing as the dunes are not the result of nesting place for Yellow-legged Gulls however some valuable peculiarities, and morphogenetic processes caused by the that have colonized the areas to such good possibilities of intervening to steer progressive deposition of classed sands, an extent that they have had a serious the processes toward natural, conform- but of the artificial accumulations of het- impact on other birdlife not only by ex- ing structures. erogeneous sediment (Figure 2b, right), cluding them, but by preying on other on which only recently remodeling and species’ chicks; while at the same time, In short, proceeding from the sea naturalization interventions have been the insularity prevents colonization by and moving inland, the habitat succes- carried out. the native herpetofauna and teriofauna. sion has the following characteristics as In this regard it is worth noting, by way of well as abnormalities and peculiarities. Hence the abnormalities in the quo- comparison, what happens in the nearby The strip of shoreline highlights a major tas, dynamics and vegetation: there is sandbar to the south-west, which is char- importance owed to the large quantity an absence of the more typical first bar- acterized by significant active embryonic of beached logs aligning the sea level rier dune species, including Ammophila dune systems: these favor an important reached by the winter storms (Figure 2a): arenaria (= A. littoralis) and Calystegia presence of friar that, due to the fact exactly the same situation as that which soldanella, while the environment is now that there is a high number of couples, occurred on beaches in ancient times, dominated by the under developed pres- enables them to protect themselves and and which today has been almost com- ence of Cakile associated with Cheno- the colony from the Gulls. pletely lost as a result of beach “clean- podiaceae ruderal nitriphilous (Atriplex ing”, an activity which creates specific tatarica above all) populating the area in An important specific aspect that is habitats and has important functions covering strips. The formation of a habi- common to the Delta sandbars is the lack involving sand appropriation and reten- tat similar to that of the first barrier of of depth that is at times almost visible tion. A specificity that differentiates this dunes is achievable however, as clearly on the sea and lagoon sides, as is clearly sandbar from the other Delta sandbars shown by the recent results of some visible in figure 4. From a preliminary and that characterizes the shoreline is planting of Ammophila that were able to

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

activate typical morphogenetic dynamics in values and criticality. The western portant corrective potential that can and vegetation. extreme (Figure 3, Sector a) is char - be activated through quota reductions, acterized by very low quotas. It has a sediment movement, and the introduc- Even more noticeable is the absence high natural value, with shores that are tion of light structures associated with of stabilized dunes. Even in the area subject to largely natural geomorpho- dune plants that trigger typical con- just east of the centre, where the logic and vegetation dynamics form- structive processes. Behind the sand depth of the sandbar would theoreti- ing embryonic dunes with structured embankment bordering the lagoon cally allow for them, there is instead, and differentiated halophilic low lying there is a wide slightly lower area dom- a high artificial plateau, dominated by areas, as well as a brackish pond. The inated by nitrophilous and reed veg- sand towards the sea and land which massive presence of beached logs in- etation (Figure 3, c2); that degrades is drenched in the winter and spring creases the beach naturality and stabil- sharply in the western corner, reaching months and compact in the summer in ity values, while the only area with a intertidal quotas on which a precious the internal areas, with extensive beds higher quota is an internal zone at the halophilous site has developed (Figure of reeds interspersed with nitrophil- extreme western edge of the earthy 3, c3). ous vegetation and soil elements with extensions that characterize the areas extreme differences in moisture. This that follow. The area does not currently The surface of the sandbar termi- habitat is free of dunal characteristics need priority interventions apart from nates in low quota sandy surfaces and although small groups of dunal and ret- the maintenance of its structures and with intertidal stretches towards the rodunal species show potentially posi- active dynamisms. Sacca (Figure 3, Sector d) at the east - tive trends. ern end. The pioneer vegetation is re- From the west extreme it passes stricted to these areas with Cakile and Even more so for the lack of vege- through a long bottleneck (Figure 3, Phragmites, replaced on the lagoon tated dunes (shrubs and trees are limit- Sector b) where the sandbar tapers off facing side by Suaeda and Salsola Ha- ed to a few artificially planted tamarice into an earthy diaphragm covered with lo-nitrophilous scrub populations. It is trees while even the initially present discontinuous nitrophilous ruderal veg- to be noted how the orientation of the Amorpha fruticosa, is underdevel- etation and grassland (Figure 4). In the area foresees, in the near future, once oped), which would indicate that con- internal concave slope the transition the intended surface towards the sea is ditions similar to the natural ones can zone towards the lagoon waters is par - entirely flooded, considerable depth of only be obtained over similar periods ticularly important, dominated by the the sandbar corresponding to this sec- through remodeling, with localized soil extensive and extremely shallow area tion, which could allow for an orienta- adjustments, necessary for the inser- with a sheltering formation of the bor - tion of the ecological succession up to tion of the dunes’ own vegetation. The dering embankment and progressively the interior habitats, starting from an retrodunal depressions are different in advancing tidal stretches. The sea fac- almost natural current condition. that, there is an absence of low salin- ing side has recently been subject to a ity humid habitats (there are only a few vast ebb flow, which reduced criticality The final parallel and elongated elbow depressions mixed with reeds), due to the extremely thin isthmus. section is currently under construction while halophilic habitats are widespread over large parts of the sandbar The next area (Figure 3, Sector c) 3 The situation described refers to 2009. Com- and its contiguous areas, in connection is characterized by the presence of a pared to which, at the end of 2012, the structure is similar to that observed in the first highlighted with the transition intertidal surfaces broad and deep artificial embankment areas. Some changes involved: section a, further facing the lagoon. (Figure 3, c1), to which excessively high deposit of sandy materials; section b, a closed stone cell intervention and consequent impor- and poorly differentiated quotas in- tant nourishment, which has significantly ex- Zoning the sandbar3 duced abnormal dynamics compared to panded the extension towards the sea and thus its stability, section e, is currently being filled, an the natural reference dynamics. operation which started in 2009. It’s state will be As a result of the realization process monitored, taking into consideration the winter storms that periodically modify the situation and and phases, some areas of the sandbar Recent remodeling of the water- a comparison of the evolution of the transects are characterized by a wide diversity front embankment has highlighted im- will be made in the spring of 2013.

64 Figure 3: Zoning of the sandbar on the basis of different morphological characteristics Flooded Mediterranean Sandy intertidal surfaces (in orange) and Intertidal strip grasslands with Salsola and Suaeda identiﬁcation of halophilic surfaces examined in the text (Aerial photo: Consorzio Boniﬁca c3 d Delta Po, 2009). c2 a b c1 e

Brackish lagoon pond with halophilic vegetation

(Figure 3, Sector e). It is made up of are concentrated at the sandbank’s fect on all the sandbar’s habitats, but the area bordered by the two shore extremes; however it does not classify are particularly fast on muddy or sandy alignments, where there is currently the large areas of the central embank- surfaces related to active depositional ebb flow, which will cause the sandbar ment, given the abnormalities that di- systems, which means that in order to to take on the planned size and shape. minish the quality of the habitats and safeguard the biocenoses worth pro- Note how a settlement consistent with impede a qualification of the habitats tecting, rather than the preservation the character of natural sand, having under the Directive. of specific locations derived from the ebbed in late 2009 with largely silty maps, it is important that the factors sediments as a result of winter storms Instead the embankment is defined and processes that enable the lagoon’s that washed out the fine components on the Consorzio Delta Po’s habitat habitat functionality, even at different and leaving the grainy ones behind, map (Figure 5), which was prepared times and locations, are guaranteed. In has rapidly shown a colonization as part of the analysis of the ecologi- this evolutionary picture, the current conforming to the characteristics of a cal value of the lagoons (Pagnoni et situation, compared to that described natural beach, with a substantial Cakile al, 2009)4. In this work the deep sandy in the two maps referred to, needs to presence. front and the rear surface (correspond- be updated. ing to sectors c1 and c2 in Figure 3) are The sandbar habitats on naturalistic defined as “non vegetated excavation There is an evident variation to the maps sand “ and “nitrophilous anthropogen- embankment labeled as “non vegetat- ic grass community”. These different situations are reflected on the naturalistic maps. The One should always bear in mind 4 In 2008, the Consorzio entrusted the assessment of naturality and quality of the Delta del Po regional habitat maps aimed at identi- that both natural and artificial sandy habitats to the Consorzio Ferrara Ricerche. The fying the types defined in reference to coastal environments are subject to work was consigned in 2009 and a summary was presented in the Quaderno Cà Vendramin Issue Directive 92/43/EEC, clearly show that rapid changes due to spontaneous or 0. More details are also available on the Delta the values attributed to the directive induced evolution. These have an ef- mapping portal http://sil.deltapo.it/web/.

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

Figure 4: in the foreground one can philic sites, in which the evolutionary map as “Mediterranean salt meadows clearly see the small processes have led to significant dif- (Juncetalia maritimi)” (similar to the earthy diaphragm, ferentiations that tend to have struc- Consorzio Delta Po Adige’s definition), with its plastic film reinforcement tures conforming to natural habitats, currently appears much more exten- introduced during as highlighted below. sive than indicated on the maps, reach- construction separating the ing the sandbar’s lagoon banks in wide beach from the The halophilic surface on the west- areas. The surfaces are currently home lagoon, covered with sparse ruderal ern extreme (Fig. 3, a), labeled “annual to an eco-mosaic complex, on altimet- vegetation. On the Salicornia and other pioneer vegeta- ric discontinuity caused by artificial or- lagoon side (left), the presence of tion of the mud and sand areas ” on igin, which summarizes almost all high intertidal transition the regional map (the Consorzio Delta Adriatic halophilic habitats. surfaces can be Po Adige map correctly describes a noted. This photo dates back to 2009; “brackish lagoon pool“), also currently The incipient discontinuous inter- the sea facing has perennial psammophilic vegeta- tidal zone on the lagoon side running artificial beach is now much larger as tion types making up eco-mosaic belts from the western extreme to the con- a result of recent of vegetation further adding to the cavity bordered by the bottleneck (Fig- ebb flow (photo: Bonometto 2009). value, unlike on the eastern extreme ure 3, sector a, b; Figure 4) is not high- where there is a thin surface shown lighted on the regional map however, on the regional map (Figure 3, d) that probably because it had not been iden- is labeled as the same type with the tified at that time. This halophilic zone, ed excavation sand” (Figure 3, Sector same annual characteristics, how- identified however on the Consorzio c1) on which, covering populations of ever without Salicornia, but Suaeda map and an indicative of a positive Cakile and Atriplex have recently de- and Salsola halo-nitrophilous vegeta- process, has significant annual pioneer veloped. Further significant changes tion.The halophilic surfaces in Figure populations to the rear of the sandbar, can be seen in the complex of halo- 3 (sector c3) labeled on the regional covering considerable areas with pre-

66 KEY Mixed lagoon sediments emerging at low tide

Non vegetated excavation sand Sandy marine sediments (sand>75%) emerging at low tide

Sandy lagoon sediments (sand>75%) emerging at low tide

Anthropogenic nitrophilous grass communities Annual mudﬂ at or intertidal sand vegetation Annual marine deposit line vegetation

Mediterranean meadows with pioneer Salicornia vegetation Annual Salicornia pioneer vegetation with muddy and sandy areas

Junctus Mediterranean salt meadows (Juncetalia maritimi) Lagoon salt meadows

Figure 5: the Scardovari tionary dynamics of these environmen- estuarine system (Khalil, 2008; Louisi- sandbar in the tal systems. Therefore, due to erosion, ana Coastal Wetlands Conservation and Charter of Habitat (Pagnoni et al, a habitat can be here today and gone Restoration Task Force and the Wetlands 2009). tomorrow, but the important thing is Conservation and Restoration Author- to verify the potential conditions for ity, 1998). In the restoration of coastal spontaneous reformation. It is there- environments, a now widely shared ap- fore a case of overcoming a singular proach is that of looking for solutions cious silty bottoms and sandy material vision related to a habitat’s presence / that integrate with the natural dynam- subject to tidal range. This situation, as absence at a given time, and evaluat- ics, favoring and channeling morphoge- described in 2010 (Gianoni et al., 2010), ing the potential over a wider temporal netic processes in order to maximize the has already undergone changes related and geographic arc instead. environment’s self conservation ability to interventions and natural dynamics (homeorhesis), bringing a dynamic equi- (the 2011 and 2012 winter storms in par- Sandbar stabilization librium between erosion and structural ticular) that are currently being moni- factors to the beach-dune system (Rose, tored to check stability and consistency. Regarding the issues of management 2009; Thompson, 2011). This type of res- and restoration of the sandbars and toration approach and management of However the sandbar’s current situa- coastlines in general, the Italian expe- coastal dune systems, aimed at ensur- tion confirms in essence, with some new rience is different to the international ing ﬂ exibility and adaptability to chang- elements, the analysis carried out in experience. For an example of a major ing environmental conditions, is of par- 2009. Observing changes over a short restoration programs currently being ticular importance today in anticipating time reminds us that, in environments carried out, one only has to look at that rising sea levels and the intensiﬁ cation characterized by prominent evolution- of the Barrier Islands along the Gulf of of marine-related weather events asso- ary dynamics, the presence or absence Mexico coastline, especially near the ciated with climate change. of habitat value is mainly linked to the Mississippi Delta, which is a strategic conditions that form basis of the evolu- component in the defense of the entire The planning solutions envisaged for

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

Figure 6a: double the Scardovari sandbar fit into this pic- spread interventions carried out in or- row zigzag windbreak ture, aiming to favor and channel both der to stabilize and manage hydrograph- structures, Stone Harbor, New Jersey. present and future morphogenetic dy- ic basins, and the removal of aggregates (picture: www.flickr. namics and ecology towards ever more from waterways has drastically reduced com; Photo: Makz, 2006). resistant and resilient dynamic equilib- downstream sediment transport (Sime- rium conditions. In applying these cri- oni et al., 2007). This often requires, in teria to the restoration of coastal sys- the restoration of coastal environments, tems one has to bear two important yet beach nourishment through the applica- limiting factors in mind: the availability tion of sediment, with movements to ori- of natural sediment fills, resulting from ent the evolution of the profiles if need coastal sediment transport and wind be. In the case of the Sacca di Scardovari transport; and sufficient space for the the sediment available for beach nour- ecological succession predicted (Nord- ishment is derived from the integrated strom, 2008). The first factor is a critical management of the sandbar/ sacca sys- issue, not only in Italy but also in most tem, which provides for the re-use of the coastal environments in that the wide- material resulting from dredging carried

68 Figure 6b: brush windbreaks out in order to maintain the hydrody- es and avoiding armoring or compac- positioned at the namic efﬁciency of the mouths and the tion phenomena that limit and possibly foot of existing dunes to intercept sacca in general. prevent wind transport (Nordstrom, the Bora wind 2008; Gianoni et al., 2010). The second transport blowing across the These origins inevitably involve the limiting factor for the development of coastline (Alberoni, use of different size sediments, that complete ecological succession on the Venezia). (Photo: A. are at times very fine and may vary ac- Delta sandbars is the shallowness of Bonometto, 2012). cording to the localization and depth of the sandbars themselves, sometimes dredging, creating high criticality and exacerbated by subtraction of space imposing, if tending towards the mor- due to infrastructure and more gener- phogenetic evolution conforming to ally the anthropic use of the territory; the naturality and functionality of the to which can be added, as in this case, Figure 6c: an example of dunes, the use of the same sediments very intense local natural erosion. a windbreak according to the different localization module and sand and stratification criteria, favoring, The establishing of a sufﬁciently deposition (Photo: A Bonometto, 2012). where possible, classification process- evolved ecological succession, so as to

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

TAVOLA 1 sea TAVOLA 1 wind a ca. 25cm a a ca. 30cm ca. 30°

ca. 15cm

trellises wind generated sand deposit from dune (+ beach) b b

50-60 cm ca. 30°

selected sand (placed or arrived)

Figurec 7: an upper beach Ammophila a morphological and functional point of side, depending on the different hydro- system.c Planting view. It should be underlined how very dynamic and wind forces that induce and phases (a, b) and foreseen important these dune environments channel the evolutionary process. The developments (c,d). are to morphological functionality, both main intervention criteria for the Scanno The dark brown lines represent the for their ability to dissipate the tempo- di Scardovari are as follows. profi le of the sand rary increase of wave energy during the - On the sea-facing side, for the en- refl ow present in the moment of planting; more intense storm surges (Thompson, tire depth directly affected by the ma- the light brown lines 2011) and for their role as a “sediment rine weather process and wind sand are profi les of the tank “ in the exchange of sediments with transport, after the implementation of wind generated sand deposits. the beach during nourishment and for the basic structures for the formation the natural restoration of morphological of the sandbar (shoreline and ebb fl ow), d quotas in exceptional marine weather interventions should be aimed at ori- erosion events. Furthermore, the pres- enting and favoring the morphogenetic d ence of barriers of dunes on the sand- constructive factors conforming to the ensure the functionality of the environ- bars restricts overwash phenomena, natural ones. The fi nal balance profi le ment from an ecosystem point of view, is avoiding the consequent loss of sedi- should therefore be achieved thanks to a fundamental prerequisite for the suc- ment, instability and breaches. the spontaneous recharging processes cess of these interventions, at least in the induced by the said interventions. sea-facing side where the formation of a Regarding the sandbars in general, - In the internal surfaces of the sand- proper active zone that stretches from different solutions should be planned bar, which correspond to the zone occu- the fi rst pioneer groups to the “gray” and evaluated for the sea facing side, the pied by the stabilized dunes, the actions dunes is of particularly importance from internal surfaces and the lagoon facing will lead to almost fi nalized structures, e 70 e TAVOLA 1

TAVOLA 1

b a

c b

wind generated sand deposit from beach

wind generated sand deposit

ca. 2 - 3 month c dc

capping residue

d ca. 1 year d e

only leaving the settling of morphologies strategies, is the artifi cial heterogeneous These variables are of primary im- to the spontaneous dynamics (somewhat embankment in the central part (Figure portance for the identifi cation and weakenede by the absence of signifi cant 3, C1), which requires specifi c, stretch-by- adoption of intervention strategies in sand recharge). stretch evaluations in relation the follow- that they differentiate surfaces allow- -On the lagoon-facing side the tran- ing variables: ing one to identify areas that require sitional environments will be planned - distance between the various points only minor interventions, based on the foreseeing works that will bring about of the embankment being examined and principle of favoring eco-morphological morphological structures that are close the sea (adequate, excessive or small); processes that conform to the natural to those expected, leaving remodeling - morphology (dimensions, depth, processes, and those in which more functions, essentially those of improve- slope, etc.) and the dynamics of the em- substantial interventions are neces- ment and expansion of intertidal surfac- bankment compared to natural condi- sary such as beach nourishment and / es, to the tidal lagoon dynamics. tions (it is important to assess whether or sediment movement. Certain wide- they are similar to or far from natural spread and often synergistic types of Different methods of intervention equilibration dynamics); intervention can be used to initiate the should be adopted in relation to the - sedimentological characteristics of morphogenetic processes aimed at the current morphological and sedimento- the sand (especially checking for select- formation of typical coastal environ- logical features of the sandbar, arising ed sand, unselected sediment with silty, ment ecological succession: from past interventions and the evolu- clayey or gravely elements); - input and movement of sediment, tionary processes induced (Figure 3). - ongoing processes of erosion / re- with modeling of surfaces; Specifi cally, the element that basically moval, or the recharging of sand by the - insertion of windbreak structures differentiates the sandbar from its inte- wind, on the different section fronts and designed to interfere with the wind re- rior, imposing appropriate intervention surfaces. moval-transport–accumulation of sand;

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Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

- introduction of basic plant species - there must be a recharge area that The use of vegetation for in the activation of morphogenetic con- is big enough for wind transport consist- morphogenetic purposes solidation and construction processes. ing of an either poorly or non-vegetated and unsaturated (usually dry) strip of The planting of psammophilic vegeta- As well as being used for beach beach; tion in the restoration of dunes, often as- nourishment, sediment input and the - wind speed must exceed the thresh- sociated with the insertion of windbreak eventual movement thereof can be use- old for periods of time that are long structures, is carried out with two dif- ful in accelerating the reconstruction enough to move and transport sedi- ferent objectives that are in most cases process of the dune ridges. To this end ment; contextual and interdependent: the embankments are to be designed - the depth, angle and height of the - to activate, support and accelerate with heights that are possibly lower beach must be such as to dissipate the the construction and stabilization pro- than those expected, so that the said incoming wave energy on the dunes in cesses of dune systems, mostly in the heights are reached with the subse- neo-formation. Conversely, beaches bands of embryonic and “white” dunes, quent deposition of sand selected by that are too high limit their interaction favoring the capture of sand and the re- the wind transport. with the sea and marine hydrodynamic sulting consolidation ensured by the root forces, reducing and at times impeding systems; Rigid structures can be useful in pro- the continuous recharging of sand and - to have an anti erosion role protect- tecting beach nourishment from more the structuring of sediment, leading in ing existing dunes, not only in the lower intense storm surges and intercepting some cases to the phenomena of beach parts where the beach is not very deep sediment transport along the coast, but armoring (Nordstrom, 2008). (a condition that might favor the ero- must be carefully planned and designed, sive and not constructive effects of the taking into account the large scale ef- There are numerous types of wind- wind, or even cause the winter storms to fects so as not to interfere negatively, break structures, their primary differ- reach the dunes), but also in the internal aggravating erosion problems down- ences being the materials from which surfaces where the changing environ- stream. Furthermore, the use of rigid they are made (e.g. wooden palisades, mental conditions expose valuable envi- structures may be necessary to limit reed lattice, strips of branches or Spar- ronments and grey dunes to abnormal and confine the mobility of sandbars ac- tina versicolor etc.), their orientation winds. cording to specific needs: in the case of (rectilinear, sloping, brush, zigzag, open the Scardovari sandbar, to ensure the or closed groups – see Figure 6), height Morphogentically speaking, the two hydrodynamic efficiency of the mouths (generally between 50 cm and 1.2 m) most important species on the Adriatic limiting burying. and by number of rows. coasts are Ammophlia littoralis and Ely- mus farctus (Thompson, 2008; Sper- Windbreak structure Their porosity is the only parameter anza et al., 2009; Bonometto, 1992), in which there seems to be substan- thanks to their stabilizing and construc- To trigger and/or accelerate the mor- tial concurrence, referred to as opti- tive functions. Important ecological and phogenetic processes related to wind mal in values ranging from 40 to 60% therefore technical differences can be energy, windbreaks structures able to (Coastal Engineering Research Center seen in the localization and roles of the “capture” and retain sand carried by the (CERC), 1984; Khalil, 2008; Nordstrom, two species: wind are both cheap and widely used. 2008; Florida Department of Environ- - Elymus farctus supsp. farctus (= These structures reduce wind speed lo- mental Protection, 2006; Grafals-Soto Agropyron junceum = Elytrigia juncea) cally and cause small dissipative vortex- e Nordstrom, 2009). The following is a constructive species that plays a es, favoring the deposition of sediments paragraphs propose, according to its very important role in the initiation of and the formation of dunes. In order for site-specific needs and in comparison colonization processes and the forma- the dunes begin to form and develop at with the different techniques available, tion of embryonic dunes, starting from the expected increased quota, certain some possible solutions deemed suit- their initial dimensions and distances basic requirements must be met (Khalil, able for the formation of dune systems not reached by the usual storms. The 2008): in the Scanno di Scardovari. species’ position in front of the sea fa-

72 TAVOLA 3

artiﬁ cially accumulated sea heterogeneous sand embankment capping wind

ca. 15 cm

aa ca. 40 cm

ca. 35-40 cm

burial wind accumulated ca. 1,5-2 m classed sand ammophila placed directly on sand

ca. + 1,5 m.s.l.m

after 1 year

Figure 8: initial phase and the ﬁ rst year of evolution and of Ammophila plants on the artiﬁ cial embankments. For sand colours see Figure 7.

73 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

Possible internal dune Different types of Ammophila species plantation littoralis windbreak structure (Tortuleto Scabiosetum Spontaneous plantations forming white in particular) Cakile colonization dunes Possible internal Possible stabilized Natural beached dune plantations bush dune Possible sand trunks or beached (Medicago marina Shore species plantation recharge trunks in strips in particular)

Low windbreak structures Possible ulterior Possible typical associated with Agropyron junceum Ammophila littoralis halophilic species of the and Ammophila littoralis plantation associated interdunal lowlands with low reeds

Figure 9: transect 1: sea; vors sea spray and eventual contact tions is linked to the biological and type, with scheme of 2: artificial reef; initial morphology, 3: submerged with salt water. An indicator species of ecological characteristics of the spe- extending where surface between the Sporobolo arenarii – Agropyretum jun- cies, primarily for Ammophila’s need possible through reef and beach; reflow, remodeling, 4: foreshore cei, in addition to its high resistance to to be gradually planted in sand with a and subsequent (intertidal zone); salt, requires less sand input than Am- selected grain size in order to develop interventions 5: beach and initial aimed obtaining colonization zone; mophila, making it also suitable for the itself and consequently, the dune too. In (potentially at 6: first embryonic restoration of differing areas of the fact, the growth of the plant is subject least) an ecological dune; succession 7: Agropyron dune. Elymus is frequently associated to the emission of secondary root sys- conforming to the dominated with Calystegia soldanella, a species tems by the stem nodes, more than that natural one (own embryonic dune; that creates ground covering surfaces of rhizomes and stolons that allow the elaboration). 8: embryonic The numbers in dune with initial on gentler slopes, which is not found on tillering that follows with the expansion normal font refer in Ammophila growth; the sandbar. of coverage. The formation of rooted meters, on different 9: white dune scales, to the quotas 10: initial interdunal - Ammophlia arenaria subsp. austra- nodes follows the planting of the plant, of the average sea lowland; lis (= Ammophila littoralis) is the main with a density (and therefore ability to level and distance 11: initial grey dune from the shore, 12: wet interdunal constructive species, as well as dynamic “arm” the dune) related to the amount while the numbers lowland; equilibrium and evolutionary element of the periodic submersion by the sand. in italics refer to 13: consolidated the sequence of the dune plantation; between the sand, wind and vegetation different elements 14: halophilic that enables the natural construction The granulometric homogeneity of or environments, lowland; and consolidation of the dunes. An indi- the wind transported accumulations according to the 15: terminal following sequence. undulation; cator species of Echinophoro spinosae of sand is of particular importance to 16: lagoon facing - Ammophiletum arenariae, at distances the species and its functions, giving margin; 17: intertidal lagoon and quotas at which the direct effects of the substrate its physical and chemical and watery surfaces. proximity to the sea normally weaken, it characteristics (permeability-drainage, takes the place of Elymus. porosity, oxygeneity) necessary for its proper development; in the absence of The success of the system interven- such characteristics there is a lack of

74 Figure 10: diagram showing the intervention conﬁguration aimed at developing embryonic dunes with the use of 50 cm high windbreak structures and the planting of vegetation (the distance from the sea is not to scale) (own elaboration). Elymus farctus plantation 4 m Calystegia plantation

Ammophila plantation

SEA

LIBECCIO SCIROCCO BORA

growth and anomalous phenomena or wooded dunes and the inter-dunal low- depths corresponding to or exceeding degenerative phenomena (silty-clayey lands. that of system, in which wind-blown elements which, when dry, appear in sand can be deposited. Here follow a powder form, retain moisture and in Sandbar system types some operational proposals (Figure 7 fact, block the interstices, hindering and Figure 8), which differ depending oxygenation by triggering processes of The interventions’ adherence to the on whether one plants isolated tufts decay similar to those that can be seen biological and ecological characteristics or rows, and the systems that appear in the older tufts in the internal areas) of Ammophila, in particular the fact that on slightly inclined (the upper area), are established. the species requires, in order ensure its or very inclined surfaces (slopes of constructive abilities, to be gradually the artificial embankment). In any This has already occurred, also in sig- planted in sand with a selected grain case, the requirements are the same: nificant areas in the upper-Adriatic, in size, can be ensured during planting the digging of holes or trenches of a systems of unselected refilled sand and/ even through simple interventions; in suitable depth and width; the upwind or surfaces without sufficient wind re- these cases the inclination of the sur- accumulation obtained by the input of charge. The expected widespread use of face (beach or embankment slope) and removed sand; reed lattice elements Elymus and Ammophila, to which Calys- the possible presence of sand that has (or similar) to trap the sand. In both tegia can be added, requires a suitable already been selected by wind action examples one expects to plant in preparation of the specific nurseries, in are important variables in the site in groups of three to five rooted trunks, order to ensure adequate availability of question. preferably including the rhizome specimens without the need to resort to parts with multiple nodes, obtained excessive extractions from the environ- In order to enable the deep planting by fanning out the tufts removed from ment. At this point these areas can be on selected sand surfaces, some simple the nurseries or the environment. The organized for the production of the main preliminary operations are necessary interventions should be adapted to species that in nature, synergistically ac- for surfaces with heterogeneous suit the site-specific characteristics company those outlined above, in order sediment refill, consisting simply of the of the sandbar with solutions that to revitalize the stabilizing dunes, the realization of holes or trenches with can be adjusted however slightly each

75 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

PRINCIPLES AND PURPOSES time according to the planting site and of about 30 cm is required; regarding period. width, one should bear in mind that the 1. To Guarantee the sandbar’s presence at sea and hydrodnamism. section will be affected by rapid subsid- Ammophila plantations and foreseen ence of the edges before settling at an in- 2. To protect and consolidate existing environmental value. developments in the upper beach clination of approximately 30 ° (“natural heterogeneous reflowed sand slope” of the sand). 3. To recuperate ecological functions (transitional habitats, reticles, dynamisms). In the upper beach area the planting Phase 2 (Figure 7, b): an initial quan- of Ammophila (together with Elymus and tity of selected sand of 10 to 15 cm (taken 4. To activate habitat diversification mechanisms and possibly Calystegia) is carried out on very from a nearby source or obtained by siev- the formation of new habitats of gently sloping surfaces, in order to acti- ing), should be placed on the bottom (this quality. vate the formation of a first line of em- step can be omitted if the pit has been INTERVENTION AREAS bryonic dunes. The objective requires the realized in advance guaranteeing a suffi- The consolidation and improvement use of light supporting structures, capa- cient amount of equal spontaneous accu- A of the structure and dynamics of ble of starting the expected processes by mulation due to the effect of wind trans- the sandbars. quickly integrating itself, and conforming port; it may also be omitted if the plants The protection and encouraging of to what happens in nature, leads to the are already in a biodegradable container B the neo-formative dynamics of salt proposal of sparse planting schemes, with filled with a fair amount of selected sand). marsh and transitional areas on the margins of the lagoon. distanced single tufts or with short lines The system is planted by covering it with starting from a quota of considerably less the selected sand at the bottom, possibly The recuperation of habitats and C transitional functions between water than two meters; the subsequent growth supported by a single reed. Downwind, surfaces and land through structural of the plant/sand systems will determine about 25-30 cm from the plant, a reed interventions on banks both on the water-side (salt marshes, mudflats the fusion of the tufts and will reach the lattice is fixed vertically to act as a trap etc.) and on the land (woodlands, height two meters, on a reinforced embry- until the tuft is able to carry out this func- bushes, freshwater areas etc.). onic dune connected to deep layers due tion by itself once it has grown. The reed The creation of a freshwater to the gradually buried parts of the plants. lattice, between 100 and 120 cm tall, and D biotype in the lagoon through the adapted to the size of the hole or trench, controlled intake of reclaimed waters and the creation of a Figure 7 shows the planting stages (a, is buried just over halfway, with 40 to 60 submerged embankment. b) and the schematization of foreseen de- cm protruding (with single plants a con- The improving and valuation of velopments (c, d). This example refers to cave towards the sea is preferred). E ecological connections with inland the system of individual lines of Ammoph- habitats. ila; similar solutions with double lines Phase 3 (Figure 7, c): About 2-3 The guaranteeing and improving could be realized through the creation of months after planting (depending on the F of hydrodynamism within the lagoon based on the ecological a dual trench with reed lattice in the mid- age of the plant, the weather and wind objectives for the two sub- dle, so as to exploit the accumulations of transport intensity) the process should lagoons. sand that form on the trellises in front of be well under way. In fact, the hole or The reinforcing of sructural and the area that is exposed to the wind, as trench should already have been filled G functional separation / transition well as those to the rear caused by down- as a result of the sand blown by the wind elements between the two lagoons (relating to D). wind vortexes, in order to form the first coming from the adjacent accumulation undulations. and beach; an initial undulation on the trellises, in part covering the Ammophlia; Phase 1 (Figure 7, a): digging a hole a good entrenching of the plant, having (or trench if for a line of plants), with up- got over the shock of its transplanting, Figure 11: overview wind accumulation (sea facing side) of re- and the beginning of secondary root for- of recuperation moved sand (this accumulation is the first mation processes are expected. (In corre- interventions in the Sacca degli source of sand for the gradual filling of spondence with the accumulation there Scardovari (own the hole due to wind transport). A depth should only be one layer of unearthed elaboration).

76 E

77 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

shells remaining, the removal of which dynamics. Below these tops there is an (brown dashes) and that following the should be considered). It ‘s very impor- Ammophila plantation that is particularly spontaneous deposition of selected sand tant that what is expected is affirmed useful in triggering the deposition of sand (beige line); the digging of a hole and its by the summer so that the plant, possi- on the top, and the consequent growth of filling with sediment downstream just be- bly planted in late winter-early spring, is the dune. The principle behind achieving low the ridge subject to wind erosion, with able to cope with the combined effects of good entrenchment and growth of the reed lattice protection; the Ammophila drought and summer temperatures. tufts is similar to that considered in the planting method with that placed inside previous type, with some differences due the hole being buried. Phase 4 (Figure 7, d): After about 1 to inclination and altitude. It is a case of year the dune will have grown significant- digging holes just below the ridge (not Phase 2 (Figure 8, b): Expected re- ly, almost completely covering the trel- trenches, so as not to trigger land sliding sults after the first year, with remodeling lises as a result of winter wind deposition. effects) in the areas marked by erosion of the surfaces due to the accumulation The growth of Ammophila, which seemed (Figure 8, a), that are deeper than the of sorted sand (in beige), covering the to stop at the end of autumn, but actu- previous types, having to compensate for top, and expected Ammophila develop- ally continued growing and differentiat- more dehydration due to exposure to the ment with secondary root platforms. ing underground through the winter, will wind and more drainage due to altitude have permitted spring tillering and conse- and inclination. Sandbar stabilization quently, maximum growth. The embryon- intervention proposals ic dune should appear in summer having The excavation takes place on an angle grown at least 60 cm, the trellises should and this provokes more extreme verticali- The criteria and types of intervention be buried, so that the development that ty of the slope upstream, the giving way of defined can be put into practice accord- follows will be completely natural in char- which must be prevented by means of pil- ing to a general scheme defined by the acter, the tuft of Ammophila should be ing before the excavation of the inclined “transect type” (Figure 9), which sum- wide and dense, with deep growths of rhi- trellises. The same plants are planted with marizes possible types of restoration ac- zomes-stolons and the initial vegetative the submerged part at an angle (Figure 8, tions according to detectable and/or ac- formation of collateral elements. a), to improve stability and ensure larger tionable ecological succession in general distances from the surface roots exposed on the sandbar. This scheme represents Ammophila plantations and foreseen to wind dehydration and high tempera- a basic reference for the executive plan- developments in the artificial tures (highest in the south-facing slopes). ning phases, showing a general indication embankments on heterogeneous of the interventions planned for each reflowed sand The high drainage of the slope sand area. It is important to note that environ- calls for a deep trench of about 25-30 cm, mental groups 1-4, the natural forces and In particular, this condition applies to revealing only the tops of the plants in or- morphogenetic processes subsequent to the remodeled embankments with mor- der to maximize the rooting and anchor- refilling and remodeling are exclusively phology that is closer to those of natural age functions of the submerged parts. due to marine factors; in groups 5-9 they dunes, where there is a range of effects Apart from this, the method is the same are due to the prevailing wind dynamics; between the slope and the top, caused as the previous type; it is clear that by and in 10 to 17 due to attenuating and sta- by wind. Many sections of the sandbar placing tufts in individual holes, one will bilizing adjustment processes. slope show a consistent deposition of initially get fragmented lines and wavy sand transported and deposited by the ridges (Figure 8, b), so it would be bet- The diagram in Figure 9 represents wind, thicker than 20 cm in places, thus ter to use plants with slightly differing ideal conditions that are only possible in permitting the direct planting of Am- heights, which require at least a couple of some areas of the Scanno di Sacca Scar- mophila (Figure 8); on the contrary, the years to create a compact front. dovari. Actually, a factor that widely af- top of the slope shows effects of wind fects redevelopment projects inherent to erosion towards the sea, with exposure Phase 1 (Figure 8, a): Schematic environmental protection purposes is the of sediment deposits and local effects planting profile. Consisting of: the origi- shallowness of the sandbar (also com- of armoring that blocks morphogenetic nal profile of the artificial embankment mon to natural sandbars), which limits its

78 Integrated project for the environmental and produc- Morphological structuring and environmental engineering interventions favoring tive consolidation and valorization of the transitional sandbar dynamisms and the natural succession of habitats between coast-sandbar- areas of the sandbar – lagoon. Involved bodies: Park lagoon. Sandbar construction interventions taking morphological dynamisms and Entity, Consorzio and ﬁshermen natural succession of habitats between coast-sandbar-lagoon into account.

Mouth opening maintenance Mouth opening maintenance

1 2 3

Defensive reef completion and speciﬁc instability point correction.

Realization of experimental brushes, in order to stabilize the sandbar.

Beach protection interventions. Involved body: Genio Civile. Integrated beach defence intervention project in favor of Stabilization of sandbar internal areas with protecting the sandbar. the formation of cells and the progressive Involved bodies: Genio Civile and Consorzio Delta del Po. ﬁlling with sandy/silty materials. 1 Km

possible development towards the inside entire sandbar. typical of coastal ecological successions thus limiting, in large parts, distances Arrangement of windbreak structures that favor more mature internal stabi- and constructive species plantations lized dune habitats. One should note that site-specificity and certain experimental In the strip of embryonic dunes, in or- characteristics of these interventions der to promote development, the plant- favor the gradual implementation of in- ing of Elymus farctus and Ammophila terventions and constant monitoring in littoralis is foreseen, with the possible order to evaluate their effectiveness and addition of Calystegia, together with the Figure 12: make appropriate changes if necessary implementation of low windbreak struc- morphological structuring, over the course of the work. Further- tures (about 50 cm). In relation to the protection and more, different solutions can be experi- transverse direction of the prevailing environmental engineering mented with in the initial phase on a first winds characterizing the sandbar (Bora intervention portion of interventions, in order to se- and Libeccio), the positioning, as an ex- guidelines for the sandbar and lect and fine-tune those that are more periment, of the trellises in two rows in adjacent areas (own efficient and that could be applied to the modules of about 4-5 m diagonally to the elaboration).

79 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

coast (Figure 10), with the second row ori- recommended (e.g. Khalil, 2008). The ar- ented perpendicular to the first, in order to rangement of the structures can be both increase its ability to capture sand (Nord- diagonal modules (of approximately 10 me- strom, 2008, Grafals-Soto and Nordstrom, ters in length), or “zigzagging” rows (Fig- 2009), is considered favorable. ure 6a, 6b, 6c), but both are solutions used for prevailing winds blowing diagonally to The two rows of trellises must be close the coastline that lead to a more natural enough to create embryonic dunes in- morphology (Nordstrom, 2008). tended to coalesce into a single system over a width of about 10-15 meters (Figure The planting of Ammophila in front 9, zones 7 and 8), bearing in mind that, as of and/or to the rear of the windbreak is reported, the expected inclination of the foreseen with the installation of the struc- growing dune system will be about 1:4- tures (Figure 7). Also in the first zone of 1:7 (Coastal Engineering Research Center dunes, but in particular near the already (CERC), 1984). An indicative scheme of existing embankment, Ammophila will be the configuration of the intervention planted at the base and on top of the sea aimed at developing embryonic dunes facing slope, in ditches formed on oblique with oriented modules in relation to the surfaces, with supporting low reed lattice prevailing winds is shown in Figure 10. trellises (about 50 cm in height) of limited The different inclination of the modules length (approximately 2 m) to the rear, in of the two rows of windbreak structures order to reinforce the upper margin of the is for maximizing the interception of wind ditch (Figure 8). transport generated by the two prevailing winds blowing obliquely across the coast- As in nature, sparse Ammophila plan- line (Bora and Libeccio). Furthermore, it tation schemes of individually spaced helps to limit the formation of currents tufts or short rows are foreseen: it is the flowing parallel to the structures and the subsequent growth of plant/sand systems consequent removal of sand in the event of that will determine the enlargement of the sea storms reaching the edges of the em- base, the consequent fusion with those bryonic dunes. nearby, and the eventual formation of ridges of dunes. The previous examined examples ref- ered to area of the sandbar that had already Maximum distance between the plants been refilled and that were characterized is about 0.75 cm - 1 m, which would require by artificial embankments, as opposed to about 2-3 years for a continuous ridge to the refill on areas that tend to be flat (most form. Ammophlia coverings are dominant importantly, zone “e” in Figure 3). In these, in dunes that are higher than about two in the zone corresponding with the first meters. This means that, similarly to that Conclusions row of dunes (zone 9 of the transept “type” which occurs in nature, the plantations in Figure 9), the positioning of high wind- should be planned so as to start from The stabilization of the Scardovari break structures (1-1.2 m) should be carried a lower height, so that the height of two sandbar is of primary importance to the out in one or two rows, depending on the meters is achieved with dune growth and general scenario of valorization inter- slope of the embankment caused by sedi- the continuous emergence of species from ventions in the Sacca, thanks to its de- ment movement and the width of the dune the accumulated sand, which will thus be termining role of maintaining the Sacca required. In cases in which there are two reinforced and connected to the deep lay- itself. Interventions on the sandbar form rows, an optimal distance between them of ers thanks to the gradually buried parts of part of a comprehensive framework of 4 times their height (about 4-5 meters) is the plant. action (Figure 11) aimed at, on the one

80 hand, ensuring ecosystem and production maintaining the typical characteristics of functions in the area, and on the other, at the transitional water; followed by the sta- improving the Sacca’s overall ecosystem, bilizing of the sandbar, at least in a fairly with particular focus on recuperating eco- large central portion, is the essential me- system deficits. dium-term objective for the conservation of the lagoon ecosystem as defined by Figure 13: the central part of The presence of the Scanno di Scar- its qualitative, functional and productive the sandbar, early dovari, and its permanence, are crucial characteristics. environmental engineering works to ensuring the morphological and hydro- 2011 (photo: P. dynamic conditions of the lagoon, while The study enabled us to confirm that Gianoni).

81 The Po Delta Lagoons October 2013

Elements of Environmental Engineering in the Stabilization of the Sacca Scardovari

the formation and management of the system, and the carrying out of necessary d), the objective could be to take the eco- sandbar requires an approach based on corrective measures; logical successions as far as the formation an evolutionary concept that integrates - Constant monitoring of the morpho- of vegetated dunes, possibly compressing anthropic intervention and natural dyna- logical evolution with assessment tools the successions so that they fit into the misms. From this viewpoint, the knowl- (lidar surveys), the monitoring of the evo- available space. edge of the phenomena of the formation lution of the vegetation (by phytosocio- and erosion of sandbars and dune systems logical surveys on relevant plots, and the Early planning indications and sur- should be the basis of any intervention documentation of the development and veys revealed some encouraging results, project that aims to ensure the medium- species coverage), fauna and landscape which to large extent confirmed the com- term presence of stable morphological observations (with photographic docu- mencement of the predicted evolution- complexes. mentation of the evolutionary phases) are ary dynamics. However, given the pre- all essential to good medium-term results; cariousness of the situation, as a result . The analyses enabled the verification - Because the planned solutions are of the failure factors considered above, it of the dynamisms as a basis for the defin- aimed at encouraging, orienting and appears that the monitoring on different ing of the interventions aimed at orienting strengthening the morphogenetic and levels over the next few seasons is nec- the morphological evolution of the sand- ecological dynamics present, they require essary in order to adapt and implement bar towards a dynamic equilibrium capable different solutions for the sea-facing slope, planning and executive measures based of guaranteeing as much resistance and the internal surfaces and the lagoon fac- on the gradual evolution in act. resilience, and hence more overall stabil- ing side. ity, as possible in the system. Here follow some key points of particular importance In the coastal and lagoon habitats adja- to the basis of the project and the carrying cent to the sandbar, interventions should out of future interventions to be integrally be integrated into specific larger scale pro- applied: jects developed in collaboration with the - Knowledge of the types of sediments relevant entities, aimed at limiting erosion moved is essential in defining their reloca- phenomena of the coast and the valorization on the sandbar, both with respect to tion of the lagoon areas as a whole. In a dy- positioning, and possibly to the stratifica- namic environment such as the sandbars, tion of refill; and it is for this reason, fur- it is essential to overcome the sectoriza- ther to the traditional preventive analysis tion of skills and move towards a unified measures and specific methods of con- overall planning system. In terms of plan- tract procurement, that the flexible man- ning, the general approach, in line with the agement of materials according to their natural dynamisms involves defining a rap- characteristics and their final destinations port that is coherent with the height/depth is foreseen; dimensions of the sandbar, and identifying - Vegetation plays a key role in the con- the correct sediments to form structures struction and reinforcement of the sand- at the different heights and distances from bars; planting interventions should there- the sea. fore be planned whilst taking into account the general and particular conditions of For the most part this amounts to stop- the Scanno and the medium-term objec- ping the remodeling and environmental tives of the project; engineering interventions the moment - The orientation and maintenance of there are pioneer species (no further than the planted vegetation must be carried out the “gray dunes”), providing the necessary for several years (initially 5) in order to en- support structures to activate natural pro- sure, not only the correct engraftment of cesses; only in areas where the sandbar is singular species, but the functioning of the deeper (250-300 m, see Figure 3 section

82 Bonometto L., 1992. Elementi per una pianificazione naturalistico ambientale della fascia litoranea Bibliografia nella Penisola del Cavallino. In: Un ambiente naturale unico. Le spiagge e dune della penisola del Cavallino. Comune di Venezia, Grafiche Veneziane. Coastal Engineering Research Center (CERC) (1984) Shore protection manual. Ft. Belvoir, VA: US Army Corps of Engineers. Fiorentin R., 2007a. Linee guida gestionali per gli interventi di rinaturalizzazione. In “Progetto Life Natura -Azioni concertate per la salvaguardia del litorale veneto. Gestione di habitat dunali nei siti Natura 2000”. Progetto Life 03NAT/IT/000141. pp.129-168 Fiorentin R., 2007b. Habitat dunali del litorale veneto. In “Progetto Life Natura -Azioni concertate per la salvaguardia del litorale veneto. Gestione di habitat dunali nei siti Natura 2000”. Progetto Life 03NAT/IT/000141. pp.75-128 Florida Department of Environmental Protection. Division of Water Resource Management Bureau of Beaches and Coastal Systems, 2006. Sand Fencing Guidelines. (04/2006). Géhu G.M., Scoppola A., Caniglia G, Marchiori S., Géhu-Frank J, 1984.Les systèmes vegetaux de la cote nord-adriatique italienne. Documents phytosociologiques, vol. VIII, pp. 485-558. Camerino Uni- versità degli Studi. Gianoni P., Bonometto A., Bonometto L., Matticchio B., 2010:Interventi di sistemazione scanno degli Scardovari, Elementi ambientali e di ingegneria naturalistica per il progetto generale ed esecutivo, pag. 61, Consorzio Delta Po, 2010, inedito. Grafals-Soto R., Nordstrom K., 2009. Sand Fences in the Coastal Zone: Intended and Unintended Effects. Environmental Management (2009) 44:420–429 Khalil, S. M. 2008. The use of sand fences in barrier island restoration: Experience on the Louisiana Coast. ERDC TN-SWWRP-08-4. Vicksburg, MS: U.S. Army Engineer Research and Development Cen - ter, https://swwrp.usace.army.mil Louisiana Coastal Wetlands Conservation and Restoration Task Force and the Wetlands Conservation and Restoration Authority, 1998. Coast 2050: Toward a Sustainable Coastal Louisiana. Louisiana De- partment of Natural Resources. Baton Rouge, La. 161 p. Mattichio B., 2009: Evoluzione morfologica recente della Sacca degli Scardovari, Quaderni Cà Ven- dramin 2010 (0):18-52 Nordstrom K. F., 2008 Beach and Dune Restoration. Cambridge University Press. Office National des Forets (France), 2002. Connaisance et gestion durable des dunes de la Cote Atlan- tique. Manuel récapitulant les enseignements du projet européen Life – Environnement de rehabilita- tion et gestion durable de quatre dunes francaises. In Dossiers Forestiers – Office National des Forets (France), n.11, 2002. Favennec J. (Direction – coordination). Pagnoni G.A., Bertasi F., Gianoni P. Rossi R., 2009. Il valore della naturalità e a gestione degli interventi nelle lagune del delta del Po, Quaderni Cà Vendramin 2010 (0): 56-103. Regione del Veneto, Segreteria Regionale Ambiente e Territorio – Unità periferica Genio Civile di Ro- vigo, 2009. Elaborazione dei dati LiDAR rilevati sulla costa del Delta del Po. Voli del 26 aprile 2006 e del 7 marzo 2009. Elaborazioni IPROS Ingegneria ambientale s.r.l Rosati, J. D. 2009. Concepts for functional restoration of barrier islands. Coastal and Hydraulics Laboratory Engineering Technical Note ERDC/CHL CHETN-IV-74. Vicksburg, MS: U.S. Army Engineer Research and Development Center. http://chl.erdc.usace.army.mil/chetn Simeoni U., Fontolan G., Tessari U., Corbau C., 2007. Domains of spit evolution in the Goro area, Po Delta, Italy. Geomorphology 86 (2007) 332–348. Speranza M., Ferroni L., Priton G., 2009. L’intervento di vegetalizzazione della duna. In Foce Bevano: l’area naturale protetta e l’intervento di salvaguardia. Regione Emilia Romagna, Assessorato alla sicurezza territoriale difesa del suolo e della costa protezione civile. A cura di Christian Marasmi. pp.26-28. Thompson R. C., 2011 Natural habitats for coastal protection and relevant multi-stressor coastal risks. Report and European scale overview. Theseus EU FP7 Project “Innovative technologies for sa- fer European coasts in a changing climate”. Deliverable OD3.3. Contributors: H. Heurtefeux, M. Milor, A. Bichot, S. Grosset. www.theseusproject.eu

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The FAO-IMOLA Project

_VARIOUS ACTIVITIES THE FAO-IMOLA PROJECT

LINO TOSINI The general objective of the FAO Italy, this paper aims to (i) broaden our Director of the Fondazione Ca’ Vendramin IMOLA (Integrated Management of La- knowledge of the mechanisms that can MASSIMO SARTI goon Activities) project is to develop improve internal circulation of tidal Chief Technical Adviser fot the IMOLA Project a plan for the sustainable manage- currents and (ii) identify the areas of BRUNO MATTICCHIO ment of the Tam Giang - Cau Hai (Hue, the lagoon that are characterized by IPROS Ingegneria Ambientale srl Vietnam) lagoon system’s natural re- lower water exchanges than others. GIAN FRANCO CASTELLI sources. Initiated in 2008, it is now in The survey focused on the southern la- TE.MA s.n.c. its second phase in which the Regione goon, from the Thuy Tu Channel to the LUANA STEFANON Veneto, through the Consorzio di Bon- Cau Hai lagoon, with particular focus Consorzio di Boniﬁca Delta del Po ifica Delta del Po, has activated its Pro- on the Tu Hien sea inlet. The basic top- getto di Cooperazione Decentrata. ographic and cartographic data were acquired from the GIS database made This work concentrates on one of available by the IMOLA project techni- the priorities of the IMOLA project, cal office in Hue. which foresees the establishing of a program for the environmental moni- A partnership was established with toring of the system and the hydrologi- the Hanoi Water Resources University, cal modeling of the Tam Giang Cau Hai which has significant experience in the lagoon, to be implemented through study areas, from which more specific automated environmental parameter data (bathymetric surveys, hydrologi- detection methods and systematic la- cal data and studies, tidal data) were goon morphology surveys, that are acquired. Partnerships with local agen- essential to the design and monitoring cies were also established and data of interventions within the lagoon en- necessary for the compilation of a hy - vironment aimed at the mitigation of dro-meteorological database contain- ongoing environmental degradation. ing chronological records of weather data and river water levels were ob- In the light of experience gained in tained in order to characterize the the coastal lagoons of the Po Delta in system’s seasonal regime. The most

The Tam Giang - Cau Hai Lagoon.

84 relevant of the activities, however, con- sisted of carrying out field studies and the implementation of a mathematical hydrodynamic model of the lagoon.

The measurement campaigns, as well as being the first step in the IMO- LA project’s environmental monitoring program, are mainly for the collection of the data set required for the development and calibration of the mathematical model. The measurements focused on Cau Hai Lagoon, Tu Hien inlet and Thuy Tu Channel. Detailed bathymetric surveys, tide recordings, flow and current measurements at the inlet and along the main tidal pathways were conducted with an ADCP. CTD measurements were also conducted in order to map the distribution of temperature and salinity in the system.

The measurements were carried out by TE.MA. S.n.c. of Faenza, Italy from 15 to 22 April 2011, on behalf of the Fon- dazione Ca’ Vendramin in collaboration with B. Matticchio and L. Stefanon as commissioned by the Consorzio di Bon- ifica Delta del Po.

85 The Po Delta Lagoons October 2013

The FAO-IMOLA Project

Thuan An outlet Tu Hien outlet

TAM GIANG LAGOON Thuy Tu channel

Huong river

CAU HAI LAGOON 0.0 -1.0 -2.0 -3.0 -4.0 0 2 4 6 Km Bathymetry (m a.m.s.l.)

Logistic support and assistance was Hien inlets. The computational grid was Tam Giang – Cau Hai Lagoon provided by the IMOLA team, which was constructed with cells of varying sizes in hydrodynamic model coordinated by Prof. Massimo Sarti. Local order to describe the morphology of the computational operators provided the boats as well as area of interest, i.e. Cau Hai Lagoon and domain. directly participated in the survey (tide Tu Hien inlet, in more detail. gauge measurements and salinity) after adequate training. The data collected, The model was calibrated and verified having been processed and validated ac- mainly based on data collected in the cording to the standards of the project, April 2011 field campaign and other data were made available in a GIS database. collected in a previous campaign carried out by IMOLA in December 2010, in order Cau Hai Lagoon grid to verify the tidal propagation results, the Numerical modeling tools developed model. by the University of Padua, which consist of a series of modules based on a finite element formulation, and which allow the solving of different aspects regard- Thuy Tu channel ing the hydrodynamics of the currents in shallow waters in a two-dimensional domain, including tidal levels and currents, dispersion of solutes and the movement of floating particles as well as sediment transport and wind generated waves, were used in the analysis. Tu Hien outlet

A 3D baroclinic module was also employed to simulate the stratiﬁed currents pattern due to salinity differences. The model area was extended to the entire Tam Giang - Cau Hai Lagoon and portions 0 1 2 3 4 Km of the ocean in front of Thuan An and Tu CAU HAI LAGOON

86 magnitude of ﬂow through the inlets and the Thuy Tu Channel, and the identiﬁca- tion of the sub-basins pertaining to each of the two mouths. In order to identify the areas of the Cau Hai Lagoon most affected from a water exchange point of view, the mapping of the residence times was carried out, among other things.

The results identify an area next to the Tu Hien mouth (about 10 km2) characterized by very low residence times (less than 6 days) and therefore has a considerable capacity for water exchange. Longer but still relatively short residence times (less than 30 days) characterize an area inside the lagoon of approximately 40 km2.

In the remaining part of the Cau Hai Lagoon and along the Thuy Tu Channel, residence times are much longer (over 2 months), therefore these large portions of the lagoon basin are characterized by an almost complete absence of tidal action, thus water circulation and exchange is exclusively due to the much weaker and uncertain action of the wind.

The model was then used to analyze a series of scenarios involving different morphological conﬁgurations of the Thuy Tu mouth, including the possibility of proceeding with the dredging of the mouth. The results obtained can be useful in identifying possible interventions that may improve the quality and circulation of water inside the lagoon.

87 The Po Delta Lagoons October 2013

Delta Med Association Activities 2011-2012

_VARIOUS ACTIVITIES DELTA MED ASSOCIATION ACTIVITIES 2011-2012

LINO TOSINI The Delta Med Association, founded in which the following themes were dealt Director of the Fondazione Ca’ Vendramin in 2002 by the General Comunidad de with: Regantes Derecha della Canal del Ebro - The issue of rice cultivation in the Medi- and the Consorzio di Boniﬁca Delta Po terranean, Adige di Taglio di Po, and which today - The modernization of irrigation in Cata- comprises representatives from nine dif- lonia, ferent Delta and Mediterranean Wetland - The future of EU Agricultural Policy, areas has, in line with its main objectives, - The management of wetlands and del- continued to carry out its activities over tas (in reference to the Po Delta), the two year period 2011-2012. - Water resources and agriculture in Egypt, Of the various activities undertaken, - Climate change impact and adaptation it is worth mentioning the constitution of strategies in the Mediterranean deltas. the Delta Med General Assembly, which took place on 7 April 2011 at the General On this occasion Delta Med President Comunidad de Regantes Derecha della Manuel Masià Marsà, presented Mr. Joan Canal del Ebro headquarters and the Maria Roig i Gran, the “Senador” of the Delta Med Association in Amposta (Tar- Comunità Autonoma della Catalogna, ragona), during which the activities car- with a document regarding the “Decla- ried out by the Association in 2009 and ration of rice cultivation as an activity 2010 were preliminarily described, its of special interest to the deltas and wet- economic management was accounted lands and of high ecological value to the for and new member Ente Parco Region- Mediterranean Area”, which had been ale Veneto Delta del Po’s inclusion in the signed by representatives of the various Delta Med Association was discussed. In Delta Med regions in Valencia in 2003, in particular, one should not forget that the order for the aforementioned Comunità 2010 Assembly that was due to be held in Autonoma della Catalogna to commit to Alexandria, Egypt, was postponed due to submitting the said document to the rel- political instability. evant European Union department.

Among the particularly interesting In August 2011, a delegation led by the topics discussed was that of Dr. Badawi President went to Cairo to observe the Tantawi (Nile Delta) on the development evolution of a new variety of Delta Med of Delta Med rice varieties being car- rice already in its last phase of develop- ried out in the Egyptian research center ment, and for which conclusive tests may in Sakha, where the selection of certain later be carried out in order to deﬁne its rice varieties is being studied in order to behavior in Spain and Italy. be presented as a joint project between Spanish, Italian and Egyptian representa- On December 5 2011, Delta Med, in col- tives as soon as possible to enable rice to laboration with the Comunidad General adapt to the issues of climate change and de Regantes held a symposium at the salt wedges. 51st agricultural fair in Amposta in the Ebro delta. The topics covered were the On April 8 2011, the Delta Med Asso- evolution of the Spanish rice varieties in ciation organized a day of conferences Egypt, with particular reference to those on “Futuro de la Agricultura en los del- with higher yields and those that are tas y zones humedes del Mediterraneo“ more tolerant to extreme drought and

88 high temperature conditions, as well as the development of irrigation techniques for the cultivation of rice and the efﬁ- cient use of water in Egypt.

The engineer Lino Tosini, Delta Med representative in Italy, made a detailed presentation of the changes affecting the evolution of the Po delta and the problems of salt wedge ingress, in which Spanish participants were considerably interested in the proposed solutions and their connection with similar problems in the Ebro delta.

In 2012 Delta Med members were affected by the incumbent consequences of economic restrictions that all Euro- pean Union countries encountered, thus resulting a reduction of intensity of the Association’s activities. Nevertheless, its members continued in following the rice varieties’ evolution in Egypt.

An interesting project developed in conjunction with schools and aimed at broadening knowledge of the environmental, morphological and productive reality of the Ebro Delta was also launched in collaboration with the Comu- nidad de Regantes de a Derecha del Ebro. This project’s success means that in the future it will be extended to all the other Delta Med realities.

Delta Med general meeting at the head ofﬁce of Comunidad General de Regantes del Canal de la Derecha del Ebro and the Delta Med Association in Amposta (Terragona).

89 The Po Delta Lagoons October 2013

Thesis Review

_THESIS REVIEW ON THE TIDALLY AVERAGED DIFFUSION IN THE VALLONA LAGOON (PO RIVER DELTA)

ANDREA DEFINA The thesis addresses the problem of When planning tidal basin viviﬁcation Professor of Hydraulics at the hydrodynamic indicators, able to indicate works it is useful to have hydrodynamic in- Dipartimento di Ingegneria Civile, Edile e Ambientale (ICEA), the intensity of water renewal process ef- dicators that are able to clearly show the Università di Padova fectiveness in shallow, micro-tidal basins. effectiveness of the proposed works. To

Graduate: ALICE SGARABOTTOLO Up to now, residence time has been the this aim, residence time (or, alternatively, Civil Engineering Degree most used hydrodynamic indicator; how- water age) is by far the most commonly 2009 /2010 Academic Year ever, this time scale has not always proved used indicator. High residence times are to be significant in identifying critical assumed to denote ineffective water re- conditions with reference to the problem newal mechanisms that in turn indicate of water renewal. This work proposes a poor water quality. However, this relation- different parameter, i.e., tidally averaged ship is not always respected, e.g., efficient diffusion coefficient, which can, together exchange processes with the atmosphere with residence time, provide useful infor- can ensure good water quality even in mation on the state of a tidal basin and the presence of relatively long residence on the effectiveness of engineering works times. In the thesis a different hydrody- aimed at promoting lagoon-sea water ex- namic indicator (i.e., not a time scale) is change. proposed: tidally averaged diffusion coef- Andrea Defina ficient which measures the intensity, av-

Figure 1: diffusive processes affecting six spots released in the Southern part of the Vallona lagoon.

t= 0 hours t= 12 hours

t= 24 hours t= 72 hours

90 eraged over a tidal period, of dispersion The spots placed close to the mainland processes, hence the mixing efficiency along the Southern edge of the lagoon of lagoon and seawaters. This indica- (spots 1 and 2), experience relatively small tor can profitably be used in conjunction displacements and a very weak diffu- with some time scales, such as residence sion: actually, these spots remain densely time, to provide information on the state packed and their expansion, if compared of a tidal basin and on the effectiveness with that of the other spots (in particular of engineering works aimed at promoting with spots 4 and 6) can be considered lagoon-sea water exchange.The evalua- negligible. Intermediate diffusion char- tion of the tidally averaged diffusion coef- acterizes spot 5 which, despite being re- ficient uses a Lagrangian particle tracking leased in a sheltered area, is affected by model coupled with a two-dimensional the current induced by the tide along the hydrodynamic model. With these models artificial channel that cut the Santa Mar- it is possible to reconstruct the transport gherita peninsula. The study analyzed the and diffusion processes of clusters of diffusive behavior of 550 spots, uniformly particles, referred to as small spots, of a distributed within the lagoon and placed conservative tracer over a series of tidal at four different moments during the tidal cycles and, therefore, to assess the tidally cycle, each delayed by 3 hours. The tidally Figure 2: spatial averaged diffusion coefficient for each averaged diffusion coefficient was com- distribution of the “spot”, i.e., for each point where the spot puted for each spot, i.e., for each initial logarithm of the tidally averaged was released. position of the spots, and for each instant diffusion coefficient, of release; then it was averaged over the D (m2/s) for the Particles are transported by the aver- four moments of release. Once the mean Vallona lagoon. age velocity provided by the hydrody- diffusion coefficient was estimated for a namic model and by a random fluctuating large number of points within the lagoon, velocity whose intensity is related to the the map of Figure 2, showing the spatial local and instantaneous diffusion coef- distribution of the tidally averaged diffu- ficient; the latter is assumed to be equal sion coefficient, was reconstructed by in- to the eddy viscosity which is provided terpolation. by the hydrodynamic model. A number of spots are released at different places The results of this study confirm, even within the lagoon, each spot being com- if only qualitatively, the capability of this posed by a large number of particles; the parameter in identifying critical condi- trajectories of all particles of each spot tions with reference to the problem of are then reconstructed and the statistical water renewal (in the present case, very analysis of particles displacement over a small tidally averaged diffusion coeffi- tidal cycle enables the estimation of the cient is computed for the Southern area tidally averaged diffusion coefficient. This of the Vallona lagoon which is known to modeling procedure was applied to the suffer low water quality). The next step Vallona lagoon as a case study. the Vallo- is to determine, quantitatively, the effec- na lagoon, is one of the micro-tidal lagoon tiveness of this parameter through the systems in the Po River Delta, intensively estimation of any link between the tidally used for fishery activities. An example of averaged diffusion coefficient and some the modeling results is given in Figure 1 bio-chemical water quality indicators (e.g., where the different diffusion experienced Chlorophyll a, dissolved oxygen, dissolved by 6 spots released in the Southern part inorganic nitrogen), recorded in different of the Vallona lagoon is shown. lagoons of the upper Adriatic in particular.

91 The Po Delta Lagoons October 2013

Thesis Review

_THESIS REVIEW SALTWATER INTRUSION IN THE PO DELTA: PROBLEM OR OPPORTUNITY FOR THE TERRITORY? ADAPTATION PROPOSALS FOR AN INTERREGIONAL AREA

PIPPO GIANONI The thesis addresses the issue of salt The phenomenon of saltwater in- IUAV Venezia intrusion and consequences associated trusion is particularly pertinent to the with future climate change in a high risk Po Delta due to the negative effects it Graduate: STEFANIA GIRARDI area such as the Po delta via a systemat- causes in both natural and manmade Doctor of Planning and Policies for the Environment - Università IUAV di Venezia ic and multifunctional approach, compar- areas. The will to study the issue and ing some similar situations in Europe and to understand whether it is possible to identifying specific directions in choos- address the problem with an approach ing coherent integrated defense meas- that is different from that of the past has ures, including adapting parameters and led to the writing of a thesis that poses technical defense interventions. The con- a fundamental question: should saline sideration of defense as a single conser- intrusion only be seen as a problem for vation act in the current state must be the Delta, or could it be seen as an op- overcome with new integrated planning portunity instead? So far a defensive ap- and design approaches also including the proach to the phenomenon has prevailed parameter of adaptation to the natural through the insertion of anti-salt barriers instability of the most vulnerable areas in the estuarine areas. These structures in policies and projects, while initiating are expensive both in terms of construc- new territorial management experienc- tion and maintenance, and are not fully es based on more flexible and dynamic effective. models. One of the objectives of this thesis The thesis was awarded the Premio Spe- is therefore to establish if this is to be ciale per la Salvaguardia del Territorio the main tool, or whether it should only at the ‘13° Premio Ecologia Laura Conti be one of a range of proposals to be – ICU 2012’ together with a scholarship used synergistically against saline infor the thesis competition on Sustainable gress phenomenon. Today, partly due to Development promoted by the Associazi- gradual changes resulting from climate one Gabriele Bortolozzo. change, an intervention with a different Pippo Gianoni approach to that which exclusively coun- ters ingress, and one that aims at adapting to the phenomenon is indispensable. The idea, however, is not to intervene only in this sense, but through the integration of different policies that can be more effective, given this phenomenon’s close connection to other fields such as climate change, subsidence, anthropogenic interventions etc. The complexity of the delta, due to its contemporary characteristics of dynamicity and instability, should be also taken into account in adaption solutions both on a planning or single project level.

The area under consideration is that of the delta polesano, for which it was decided to use the NATREG1 area as a

92 point of reference, so that the proposals nomenon of saline ingress, the main risks presented are for the most part applica- to the delta and applicable solutions. This ble within the territory, and at the same tool is aimed at both public and private time can serve as an example for simi- administrators in order to promote wide- lar contexts. The thesis was developed spread awareness. through the analysis of issues relating to salt intrusion, followed by a description The proposals made in the fact sheet of the delta and existing works or those refer to various themes, highlighting the still under construction, to limit the phe- existence of a wide range of possibilities nomenon analyzed. It goes on to discuss that allow one to act on several fronts, all methods used in other areas, particu- the while contributing to achieving the larly in the Netherlands and Spain, which same objective. In order to define and get are considered key examples in the im- a better understanding of some issues, plementation of appropriate measures existing projects in progress in relation to reduce the phenomenon within the to various areas were considered in addi- analyzed territory. Finally the thesis pro- tion to innovative proposals. Among the posal, in which all indications concerning more important proposals, the need to the adaptation to salt intrusion in the Po apply ‘Continuous protocol ‘ in a practical Delta are looked into, is described. way and for the effective control of the waters of the Po basin by higher-level au- The achieving of the objectives of the thorities3, was evident. The conversion of thesis can be carried out along three vegetation into crops that consume less main lines, starting from the develop- water and are able to withstand higher ment of the major risks threatening the levels of salinity as well as the realization delta: subsidence, salinization and land- of multifunctional basins throughout the slides. The risk of subsidence was taken territory is also encouraged. Further pro- into consideration first and was then cor- posals both structural and not, relating related to the risk of salinization2. This to various themes have been associated was followed by the preparation of a map with the aforementioned fact sheet. of areas susceptible to salinity, taking the delta habitats and land-use into consider- The definitive guidelines will be inte- ation. The intersection of these different grated with existing projects, such as sa- maps led to the creation of a map of ar- line barriers, bearing in mind that these eas potentially at risk of salinization that, works could be part of a more compre- associated with the hydrogeological risk hensive proposal, incorporating solutions map and three different climate change of different types, and also having an im- scenarios, led to the identification of po- pact on the development of the territory. tential risk areas in the Delta del Po. The decision not to consider a single area 1 for the application for the various pro- The “Managing NATural Assets and Protected Areas as Sustainable REGional Development An adaptation map was created from posals is based on the need to deal with Opportunities” project aims to promote the the processed data obtained, which in- an environmental phenomenon as com- inter-regional sustainable development of the area through the natural resources and pro- cluded actions aimed not only at adapta- plex as salt intrusion on several fronts. tected areas’ given potential. tion and saline ingress but also at climate 2 Constructed using innovative methods due to change (such actions can be seen in The multifunctionality of some of the the lack of data. Figure 1). The proposals outlined on the proposed solutions, but above all the 3 The proposal takes the realization of the Auto- map were also included in a fact sheet, variety of themes, is aimed at covering rità di Bacino del fiume Po’s ‘Piano del Bilancio designed to raise awareness of the phe- as many geographical areas as possible Idrico’ into account.

93 The Po Delta Lagoons October 2013

Thesis Review

Master’s degree course in Planning and policies for the Environment - Thesis - Academic Year 2010-2011 Supervisor: Giuseppe Gianoni Co-supervisor: Francesco Musco Co-supervisor: Lino Tosini Candidate: Stefania Girardi [email protected]

94 KEY:

Study area boundary Source: IUAV di Venezia Constructed area Source: ADBPO Medium priority saltwater intrusion for the management of stored freshwater release Source: personal elaboration of Consorzio di Bonifica Delta del Po data High priority saltwater intrusion for the management of stored freshwater release Source: personal elaboration of Consorzio di Bonifica Delta del Po data Sandbar protection and nourishment Source: personal elaboration of Consorzio di Bonifica Delta del Po and Pianura di Ferrara data Estuary maintenance in mixed area Salt/freshwater estuary maintenance Source: personal elaboration of Consorzio di Bonifica Delta del Po data Creation of a structured ecological sea habitat of salt/freshwater Source: personal elaboration of Consorzio di Bonifica Delta del Po and Pianura di Ferrara data Priority for urban coastal areas Source: personal elaboration of Consorzio di Bonifica Delta del Po data Medium priority for coastal urban areas Source: personal elaboration of Consorzio di Bonifica Delta del Po data First defense embankment reinforcement Source: personal elaboration of Consorzio di Bonifica Delta del Po data Riverbank systemization Source: personal elaboration of Consorzio di Bonifica Delta del Po and Pianura di Ferrara data Priority towards drainage/promiscuous network Source: personal elaboration of Consorzio di Bonifica Delta del Po and Pianura di Ferrara data Conservation and enlargement of holms Source: Consorzio di Bonifica Delta del Po Conservation of existing water reservoirs and the connection thereof to the proposed ecological network Source: IUAV di Venezia supplied by Provincia di Rovigo and Provincia di Ferrara Creation of water reservoirs Source: personal elaboration of Consorzio di Bonifica Delta del Po data

Conservation of existing phytoremediation reservoirs and the connection thereof to the proposed ecological network Source: personal elaboration of C. di Bonifica Delta del Po Creation of phytoremediation reservoirs Source: personal elaboration of Consorzio di Bonifica Delta del Po and Provincia di Ferrara data Lagoon vivification interventions in collaboration with the economic activities, based on existing projects Source: personal elaboration of Consorzio di Bonifica Delta del Po and Provincia di Ferrara data Protection of the lagoon environments Source: personal elaboration of Consorzio di Bonifica Delta del Po and Provincia di Ferrara data Maintenance of existing shrub, herbaceous and poplar vegetation areas Source: personal elaboration of Provincia di Rovigo e Ferrara data Conversion to less water dependant cultivations with existing ecological de- pressed environments and widespread interventions in the territory Source: personal elaboration of Consorzio di Bonifica Delta del Po and Consorzio di Bonifica Pianura di Ferrara data Conversion to rice crops Source: personal elaboration of Consorzio di Bonifica Delta del Po and Consorzio Bonifica Pianura di Ferrara data Conversion to vegetable crops Source: Consorzio di Bonifica Delta del Po CreationCreazione of valli di da valli pesca da (embanked pesca Fonte: fishing elaborazione lagoons) personale su dati del C. Bonifica Source:Delta personal del Po eelaboration C. Bonifica of Pianura Consorzio di Ferrara di Bonifica Delta del Po and Consorzio Bonifica Pianura di Ferrara data Maintenance of existing woodland and connection to the proposed ecological network Source: personal elaboration of IUAV di Venezia data supplied by the Provincia di Ferrara Valorization of natural asset areas Source: personal elaboration of Provincia di Rovigo and Provincia di Ferrara data Implementation and structuring of the natural network with valorization of existing environments Source: personal elaboration of LIDAR survey

Creation of biotipe and marsh environment along the lagoon bank to stop salinity Source: personal elaboration of Consorzio di Boniﬁca Delta del Po data Drinking water checkpoints Source: personal elaboration of Consorzio di Boniﬁca Delta del Po data

Master’s degree course in Planning and policies for the Environment - Thesis - Academic Year 2010-2011 SALTWATER INTRUSION IN THE PO DELTA: SALINITY AND CLIMATE CHANGE PROBLEM OR OPPORTUNITY FOR THE DELTA? Supervisor: Giuseppe Gianoni Co-supervisor: Francesco Musco Co-supervisor: Lino Tosini Candidate: Stefania Girardi [email protected] Modiﬁcation proposals for an inter-regional area ADAPTATION MAP

95 The Po Delta Lagoons October 2013

Thesis Review

and is therefore a problem that has no from different sources corresponding to limits. Furthermore, the proposals cover the inter-regional scope examined. Given both the basin as well as the local area, the scarcity of studies relating to salinity in order to consider affecting factors up- in the delta area in question, the need stream of the delta and areas in which for coordinated monitoring between dif- the phenomenon occurs. In the end, cer- ferent regions in relation to this theme tain existing plans that could be useful in should therefore highlighted. Among the improving the area but lacking in aspects results, it should also be noted how the related to saltwater ingress, were consid- theme of salt ingress provokes predomi- ered in order to delineate the possible nantly negative effects in different areas, points of intervention and integration. however it must be pointed out that this One refers in particular to the Piano Ter- phenomenon could also be the agent for ritoriale di Coordinamento provinciale di new planning stimuli capable of increas- Rovigo, the Piano di Gestione della ZPS ing the development of the territory and IT3270023 Delta del Po and the Piano di at the same time achieving effective Gestione dell’area pilota nell’ambito del results regarding other problems. This progetto NATREG. theme should therefore be seen as an improvement opportunity for the delta The aim of the thesis is to study an en- from various points of view, which at the vironmental issue that affects the territo- same time will allow for ecological, eco- ry and water, which in turn affects human nomic and social development. life. The careful analysis of this process should allow for more observant plan- ‘It is possible to build a new delta one ning in order to solve certain problems step at a time.’ from the outset. It is necessary therefore to emphasize the need to ensure greater cohesion in the management of the territory. The will to make proposals that are useful to the area without constraints arising from administrative or bureaucratic limitations has made it possible to stretch out and to allow for an overall proposal that is not only different but also in-depth and innovative. In conclusion, the thesis subject matter is of great importance in that it would enable the territory to better address the problems caused by climate change, and the application of a different management approach would not only enable greater productivity and improve relationships with the agricultural and ﬁshing sectors, but would also increase biodiversity.

The thesis has therefore enabled us to better our knowledge about salinization in the territory and bring together data

96 THE PO DELTA LAGOONS Editor: Consorzio di Bonifica Delta del Po By the Consorzio di Bonifica Delta del Po via Pordenone, 6 - 45019 Taglio di Po (Rovigo) October 2013 Tel. 0426 349711 - Fax 0426 346137 [email protected] www.bonificadeltadelpo.it sil.detapo.it

Commissione Tecnico-Scientifica e di sovrintendenza dell’attività nelle lagune del Delta del Po: Prof. Luigi D’Alpaos, Università di Padova Prof. Francesco Donati, Professor of Agricultural Policies and Economies Prof. Pierfrancesco Ghetti, Università Ca‘ Foscari di Venezia Prof. Pippo Gianoni, Università IUAV di Venezia Prof. Remigio Rossi, Università di Ferrara Ing. Lino Tosini, Director of the Fondazione Ca’ Vendramin Ing. Giancarlo Mantovani, Director of the Consorzio di Bonifica Delta del Po

Production of the edition and project series: Consorzio di Bonifica Delta del Po

Editing: Giancarlo Mantovani, Maria Saccon, Michela Casagrande

Graphic design and layout: Dasler comunicazione

Project coordination: Tepco S.r.l.

Translations: Stephen Trollip, with contribution by Andrea Defina pages 90-91.

Contributing editors: Alberto Agnetti, Andrea Bonometto, Lorenzo Bonometto, Maurizio Conte, Francesco Donati, Elena Fabbro, Fabrizio Ferro, Pippo Gianoni, Giancarlo Mantovani, Bruno Matticchio, Silvano Pecora, Angelo Rubino, Italo Saccardo, Massimo Sarti, Tommaso Settin, Alice Sgarabottolo, Lino Tosini, Pietro Traverso, Davide Zanchettin, Marco Zasso

Photographs: Andrea Bonometto, Lorenzo Bonometto, Consorzio di Bonifica Delta del Po, Francesco Donati, Fondazione Ca' Vendramin, ENEL, Pippo Gianoni, Bruno Matticchio, www.flickr.com; autore: Makz

© 2013 Consorzio di Bonifica Delta del Po. All right reserved. No parts of this book may be reproduced in any form or by any means, electronic or mechanical, including photocopying, without permission in writing from the publisher.

Every effort has been made for contacting the copyright holders concerning the material included in this volume. For the cases where it has not been possible, we ask you to please contact the publisher.

97 The Po Delta Lagoons October 2013 THE PO DELTA LAGOONS BY THE CONSORZIO DI BONIFICA DELTA DEL PO OCTOBER - 2013

THE PO DELTA AND THE HYDRAULIC EFFICIENCY OF ITS DISTRIBUTARIES AND OUTLETS: THE STATE OF THE ART OF STUDIES AND KNOWLEDGE

MONITORING THE WATER QUALITY IN THE PO DELTA LAGOONS: ANALYSIS OF CHEMICAL-PHYSICAL PARAMETERS MEASURED BETWEEN 2005 AND 2010

SHELLFISHING IN THE PO DELTA LAGOONS, VENETO: SOCIO–ECONOMIC ASPECTS

ELEMENTS OF ENVIRONMENTAL ENGINEERING IN THE STABILIZATION OF THE SACCA SCARDOVARI THE PO DELTA LAGOONS

OCTOBER - 2013 98