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Home , Province of Gorizia, Torre (river)

SHORT REPORT

Lead Author/s Dr. Chiara Calligaris Lead Authors Coordinator Prof. Franco Cucchi

Contributor/s Dr. Philippe Turpaud Date last release 30.05.2015 State of document Final version

The project is co-funded by the European Union, Instrument for Pre-Accession Assistance

INTRODUCTION The pilot area corresponds to the Isonzo Plain located in the northeastern side of the Venezia Giulia Region (extreme NE ) at the border with . Its extend approximately between latitude 45° 58’ 00” and 45° 49’ 00” and longitude 13° 20’ 00” and 13° 40’ 00”, WGS1984, UTM ZONE 33N. The Isonzo Plain is the eastern end of the Friuli Plain and has genetic and hydrogeological characteristics typical of lowland areas, facing the sea and sited at the foot of hills. It is an areal arched as the course of the Isonzo River, which extends from the outlet at the italian-slovenian border into the plain to the sea and the lagoon of Grado (about 35 km long 10 wide). The plain is the result of the combined actions among the alluvial deposits from E transported by Vipacco and Soča rivers and those from the N brought by the Judrio and Versa streams and and rivers. The fluvial deposits, interacting with the ones from the , took to the construction of the plain, often giving rise to furniture lagoons. Deposits fill what we might call the paleovalley of Vipacco, Isonzo Torre and Natisone rivers: bedrock is partially made up by cretaceous limestones, in part by terrigenous facies of Flysch (Tertiary) and deepening hundred meters from E to W and from N to S. The corrugations related to the main tectonic lines approximately E-W oriented (sometimes partially broken by transcurrent N-S) complicate the bedrock morphology.

According to the characteristics of the deposits, the Isonzo-Soča Plain (Figure 1) is divided in two areas: the High Plain to the North and the Low Plain to the South. The High Plain at its North edge has the Collio Hills, made up by marlstones and sandstones of the Eocene Flysch. To the South are present instead the cretaceous limestone reliefs of the Karst Plateau. Coarse and very permeable deposits that hold a well-developed phreatic aquifer mainly constitute the High Plain. The rivers have an influent character with respect to the High Plain; for this reason, Torre and Judrio rivers remain dry most of the year. Isonzo/Soča River loses about 25% of its discharge. The river losses, together with effective infiltration and run-off waters flowing from the hills, actively recharge the phreatic aquifer of the High Plain.

Proceeding towards the Low Plain from North to South, the phreatic aquifer joins into a multi-layered aquifer system characterized by alternating gravel-sand and clay-silt deposits. Due to the southward permeability decrease, the High Plain phreatic waters outflow in correspondence to a NW-SE wide area displayed as a resurgence belt. Here waters are rising creating an outflow that can be identified as a water quantity and quality indicator. The significant phreatic aquifer and many rich artesian aquifers represent an important natural wealth, in terms of quantity, quality and ease of supply. The aquifers available in the plain are used for different purposes: drinking, household, industrial, agricultural and farming. They serve more than 350.000 inhabitants considering the ones living in the alluvial plain but also the ones of the Trieste city.

Sloveni Torre River a

Isonzo/Soča River

Friuli Venezia Giulia Region

Airport

Adriatic sea

Figure 1: Test site area (in red) and the surroundings.

Airport

Figure 2: AcegasApsAmga pumping wells sited northern of (Trieste) Airport.

Gorizia

Savogna d’Isonzo

Figure 3: IRIS ACQUA pumping wells sited close to and Savogna d’Isonzo cities.

Water supply is the provision of water by public utilities, commercial organisations, community endeavours or by individuals, usually via a system of pumps and pipes. In this view, the Isonzo/Soča plain is the area in which are present two different water supply systems: one is AcegasApsAmga supplying Trieste town and partially city (Figure 2); the other one is IRIS ACQUE (Figure 3) supplying all the 25 municipalities of Gorizia Province with its 18 pumping wells. The rest of the small towns and villages is supplied by domestic wells. In the Gorizia Province, in the High Plain, the number of withdrawing wells is 668, while in the Low Plain is 2376 (Zini et al., 2011). If we look at the withdrawing points, the numbers increase: 1044 in the High Plain and 2589 in the Low Plain. If we analyse the whole groundwater balance, the waters collected in the Isonzo/Soča drainage basin are recharging the High Plain of a value equal to 144,5 m3/s (Figure 4). Of this number, 37,4 m3/s are the m3 influencing the water table. 4,2 m3/s is the contribution to the recharge due to the effective infiltration, 1,9 m3/s is the well withdrawals, 10,0 m3/s is the loses that contribute to the recharge of the Karst areas. In the end, 29,7 m3/s is the contribution of the High Plain to the resurgence belt of the Isonzo/Soča plain. If we cut out the water amount drained by the resurgence belt (16,0 m3/s), what is recharging the Isonzo/Soča Low Plain is 13,7 m3/s. Of these, only 2,1 m3/s are the well withdrawals estimated in the Low Plain (Zini et al., 2011). Figure 4: Groundwater hydrogeological balance of the entire FVG Region. The red box is highlighting the Isonzo/Soča plain test site area (modified after Zini et al., 2011).

This allow saying that in the study area the water quantity present in the alluvial deposits is significant, but the ever-increasing demand requires careful withdrawal planning to maintain the sustainability. Now, the water quality is good. AcegasApsAmga within the years (1970s till now) had to face with atrazine and its metabolites issues that are visible on data analysis but with few criticisms (up to 0,05-0,06 g/l of disetilatrazine). Also ARPA FVG (2015) referring to the groundwater data of 2010 and on phreatic ones (2013), is declaring the good quality of the groundwater bodies. Regarding the residues of plant protection products, after many years from the prohibition of use of atrazine (1990), its degradation products (metabolites) are still present in the aquifers of large areas of the plains also in the groundwaters (Autorità di bacino, 2010). This is less visible in the concentrations analyzed in the AcegasApsAmga wells, also because their wells reach important depths (-200 m). The problem is more felt by IRISACQUE that has its wells in the northern sector of the Isonzo/Soča High Plain (Figure 3). Here the wells are reaching risible depths (-40 and -25/-30 m) in the phreatic aquifer being more vulnerable to all the pollutants due to the wrong land use and to the cross-border contamination. As known, in the groundwaters, within the 1990s, atrazine and disetilatrazine were identified. To date, the groundwater quality is still influenced by the presence of herbicides. In the Isonzo/Soča river basin, atrazine metabolites have been detected in concentration higher than 0,10 μg/l (drinkable limit according to D.Lgs. 31/2001) only in Povoletto municipality in the period 2000-05. It has long been started to detect, northern of , the presence of other herbicides: terbuthylazine and in particular, its metabolite, the desetilterbutilazina. This herbicide had been found also in a well (agricultural use) sited in the village of (). In some wells of the network, sporadic exceedances of the limit of 0.10 μg/l were detected in recent years, also for herbicide Alachlor (Comune di Premariacco) and Metolachlor (Cormons, the whole period within 2003-07). The desetilterbutilazina is present in significant concentrations, equivalent to more than 0.10 μg/l in the previously mentioned well (Angoris well in Cormons municipality) (Autorità di bacino, 2010). For this reason, especially in the northern part of the study area, it is very important to follow a monitoring program able to verify the quality of the groundwaters. Land use data in Italy have been obtained from the Friuli Venezia region (http://irdat.regione.fvg.it, Moland database, JRC-IES, 2002). Land use data in Slovenia have been obtained from the Ministry of Agriculture, forestry and food of Slovenia (http://rkg.gov.si/GERK/viewer.jsp). As the original database are different, land use classes in Italy and Slovenia diverge. To analyse the land use data in a unique map a merging of the numerous original classes was necessary. We reduced their number to seven common classes (agriculture, natural environment, Industry, Quarry/landfill, urbanized area, water surface, sport and leisure facility). The original soil map data were provided by ERSA (Michelutti et al., 2006) and Center za pedologijo in varstvo okolja (Šporar et al., 1999). The soil type classes have been reduced for legibility and comparison purposes on both sides of the border. Original maps follow the World Reference Base for Soil (IUSS Working Group WRB. 2007). The homogenization and simplification mainly consisted in maintaining only the reference group and the main qualifier.

Table: Test areas in Italy

Name of the area Isonzo/Soča Plain

Phreatic in the northern side and confined multilayered WR aquifer in the southern side.

Gorizia, Trieste, Monfalcone (All the Province of Gorizia Related City and a wide part of the Trieste Province)

45.9413046 N Geographical coordinates 13.6215457 E (of Gorizia town)

Altitudinal range 0-80 m a.s.l.

Size 168 km2 (the whole study area)

Morphology Mainly plain area having in the NW and in the E the hills

Porous aquifer. Mainly phreatic in the northern part and Aquifer type confined in the southern, downstream the resurgence belt

Surface water interaction Isonzo/Soča river has an influent character

Geology Limestone, Flysch, alluvial deposits

1397,5 mm Mean annual precipitation (1103min – 1955 max)

13,1°C Mean annual temperature (-11min 39max°C)

Skeletic cambisol 37,30%; Calcaric cambisol 18,59%; Skeletic regosol 15,50%; Eutric cambisol 12,09%; Soil types calcaric fluvisol 11,51%; covered 2,47%; other 2,54% (the whole study area)

Agriculture 58,81%; Natural environment 10,50%; Urbanized area 22,48%; Water surface 3,56%; Industrial Land uses area 3,14%; Sport and leisure facility 0,94%; Quarry and landfill 0,57% (the whole study area)

Protection areas According to the Italian low D.L. 152/2006

4 m3/s from wells withdrawals; 16 m3/s from the spring Water abstraction belt

CITED REFERENCES

ARPA FVG, 2015 - http://www.arpa.fvg.it/cms/tema/acqua/acque-sotterranee/approfondimenti/Lo- stato-delle-conoscenze.html

IUSS Working Group WRB. 2007. World Reference Base for Soil Resources 2006, first update 2007. World Soil Resources Reports No. 103. FAO, Rome.

Autorità di bacino, 2010 - Piano di gestione dei bacini idrografici delle Alpi Orientali. Bacino del fiume Isonzo. Sintesi delle pressioni e degli impatti significativi esercitati dalle attività umane sullo stato delle acque superficiali e sotterranee. 46 p.

JRC-IES, Institute for Environment and Sustainability, Joint Research Centre, European Commission, 2002 – Relazione finale MOLAND-FVG Consumo ed uso del territorio del Friuli- Venezia Giulia, 126p.

Michelutti G., Barbieri S., Bianco D., Zanolla S., Casagrande G., 2006 – Suoli e Paesaggi del 2. Provincia di Gorizia e Trieste. ERSA, Pozzuolo del Friuli, 636 p.

Šporar M., Rupreht J., Prus T., Vrščaj B., Vidic N.J., Zupan M., Knapič M., Lobnik F., 1999 – Pedološka karta Slovenije 1:25.000. Center za pedologijo in varstvo okolja, Biotehniška fakulteta, Lubljana.

Zini L., Calligaris C., Treu F., Iervolino D., Lippi F., 2011 – Risorse idriche sotterranee del Friuli Venezia Giulia: sostenibilità dell’attuale utilizzo. EUT, 89 p., ISBN 978-88-8303-314-8.

The project is co-funded by the European Union, Instrument for Pre-Accession Assistance