Water Resources Systems—Hydrotogical Risk, Management and Development (Proceedings of symposium 334 HS02t> held during IUGG2Û03 al Sapporo. July 2003). IAHS Publ. no. 281. 2003.

Sustainable water resources management in the Dragonja catchment,

MITJA BRILLY University of Ljubljana, Faculty for Civil Engineering and Geodesy, Hajdrihova 28, Ljubljana, Slovenia [email protected]

LIDIJA GLOBEVNIK Water Management Institute, Hajdrihova 28c, Ljubljana, Slovenia. lidiia,globevnik(n)guest,arnes,si

Abstract The Dragonja River basin is situated right on the border between Slovenia and . Due to various political disturbances after the First and Second World Wars and poorly managed agriculture, the catchment depop­ ulated in recent decades, leaving forests to develop in the abandoned agricultural fields. The changes in land use changed the hydrology of the catchment a great deal. Today, the area is developing again. Several conflict situations have arisen due to three doctrines promulgated by different parties. The first doctrine is the development of the area as a drinking water supply and food production resource on both the Slovenian and Croatian sides. The second is tourist development (airport extension, golf resort) of the valley. Due to its natural and landscape values, a plan to protect the greater part of the catchment as a landscape park has also been made. There are three main issues that should be considered to support sustainable management of the catchment's water resources: How to preserve the area as an important natural and cultural heritage entity and to protect the water resources? How to satisfy water demands in the Slovenian coastal area? And, how to manage flood protection? The important tools are the management of river corridors and erosion spots to reasonably control the hydrological characteristics and to protect endemic and other important water flora and fauna species.

Key words catchment management; Dragonja; experimental watershed; water policy

INTRODUCTION

To promote sustainable management of water resources issues such as long-term impacts of the past and the existing management practices in a catchment should be analysed and the impact of new development plans (that increase population, trans­ portation and economic activities) on the catchment's water dynamics should be predicted or simulated. At the practical level, development plans are made operational mostly through land and water use planning and legalization of water resource protection zones. Therefore, analyses of trend processes of hydrological components and the hydro-morphology of rivers and groundwater bodies are very important. To give suitable answers to policy makers, the scientists working on these questions should also understand the relevant political and economic issues. This is even more important when international catchments are at stake. On the Dragonja River, which happens to be a natural boundary between Slovenia and Croatia, various scientific Sustainable water resources management in the Dragonja catchment, Slovenia 335

Fig. 1 General picture of the Dragonja catchment.

tools were built to enable us to participate in the management processes. In this paper, water policy issues are presented, scientific considerations are analysed and actions for sustainable management are proposed.

GENERAL CHARACTERISTICS OF THE DRAGONJA CATCHMENT

The Dragonja River catchment is situated in southwest Slovenia, in the northern part of the Istrian Peninsula. It flows westward into the North (Piran Bay). At its mouth is a wetland (Secovlje salt pans) protected by the RAMSAR convention; the Dmica and Jernej streams also discharge into the wetland. The Dmica used to be the Dragonja's tributary, but when the Dragonja was regulated near its mouth, they became separated. The surface runoff area of the Secovlje salt pans covers 142 km", 116 km2 in Slovenia and the rest in Croatia, the bordering country. Close to the Dragonja estuary there are two karst springs (Buzini and Gabrijeli) with a karst catchment that is mostly in Croatian territory (73 km2 area). Taking into consideration all the basin sub-units of the Secovlje salt pans, the area covers 215 km2 (see Fig. 1). The catchment consists of long flat ridges (up to 400 m a.s.l.) above the deep and narrow river valleys, where the majority of the settlements have developed in the distant past. There are 5860 inhabitants; depopulation began in the 1960s, but in the late 1990s ceased (Globevnik, 2001). The area has a distinct rural character. The plots of land owned by one family, are traditionally very small, therefore there are virtually no large farms on the surrounding hills. Larger farms can be found only in the valley near the Dragonja estuary. Today, some new plantation areas on the hills are being developed (vineyards, olive groves). 336 Mitja Brilly & Lidija Globevnik

The average annual temperature is 14°C on the coast and 10°C inland. The average precipitation on the sea coast is 900 mm, whereas on the eastern side of the catchment it reaches 1200 mm. The hydrological characteristics at the Podkastel station (87 1cm2) are as follows (Globevnik, 2001): - average monthly low water discharge (1971-1995): 0.36 m3 s"' - annual mean flow (1971-1995): 1.16 m3 s"1 - average rainfall/runoff coefficient: 0.36 - high water peaks (autumn): 98 mJ s"1 Geologically the area is composed of Eocene flysch (alternations of sandstone and marlstone layers with calcareous conglomerates and breccia). The exception is the Upper Cretaceous limestone on the area's southwestern edge. Soil is mostly carbonate rendzina, while some hill ridges have brown eutric soils. In the valley, fluvisols have developed on calcareous alluvium. The Dragonja valley bottom is covered with alluvium. It mainly consists of clay with some gravel and sand. There is hardly any groundwater flow. The alluvial aquifer lies on the impermeable flysch, covering the majority of the catchment. Due to the flysch substratum, the hilly area of the catchment is impermeable, except for the southern side of the catchment, which is part of the karst plateau (limestone and dolomite). The so-called Savudrija-Buje thrust is situated in the place where flysch meets the plateau. Here, karst springs that drain the northern area of the Buje plateau, occur. Beneath the Eocene flysch lies a Palaeogene aquifer with low permeability. Its thickness is between 50 and 160 m (at the valley downstream). It has no contact with the Dragonja stream. It is recharged from limestone areas, extending eastwards from the catchment.

WATER POLICY ISSUES

Historically, the catchment was an important food supply area for the cities located along the Gulf of Trieste. Due to the intensive land use (agriculture, stock) in the past, erosion processes have been severe. In the first half of the 20th century, the flowing water potential was used at more than 60 water mills to produce flour. Due to its weak sociological and economic potential after World War II, the area was depopulated and agriculturally abandoned until recently. The River Dragonja became a state border in 1991. The main freshwater problem is the deterioration of its quality due to pollution from villages that have no sewerage systems and treatment facilities. Due to the incr­ easing trends in plantation food production, nonpoint source pollution is endangering the waters even more. There is a high demand for irrigation of vegetation and fruit plantation areas in the valley. Since the national irrigation programme has declared the Dragonja valley as high priority land for agriculture, additional water is needed to meet various demands (MKPG, 1998). This is why construction of the Pisevec water reservoir on the Drnica River is under consideration. Deep groundwater pumping and small reservoirs on the Dragonja River tributaries have also been considered as alternative water sources (VGI, 2000). At the beginning of the 1990s, the area was proclaimed as an important biodiversity reserve (Wraber, 1987; Krystufek et al., 1987). Consequently, there have been a number of nature protection actions to prevent implementation of agricultural and water development projects in the area (Krizan, Sustainable water resources management in the Dragonja catchment, Slovenia 337

2002). The river itself has already been declared a natural heritage at its two longer sections, and if successful, the greater part of the catchment would be protected as a landscape park. In the Bay of Piran, there is an important mari-culture area. The border between Croatia and Slovenia is not final yet, and consequently the Bay's marine resources have an enormous political value. The brackish water area with active salt pans is under Ramsar protection. The future of the area is uncertain due to the possible abandonment of the traditional salt production. The area is also endangered due to the transport, tourist and recreational development plans (airport extension, fast car racing, plans to construct a golf course, tourist visitors, pollution). To support a sustainable management of water resources, the following water issues and facts should be taken into consideration: - The Dragonja flows into a brackish, marsh area with salt pans and great fish farming potential. - Surface water quality is deteriorating due to lack of wastewater collecting systems (sewerage system) and development of intensive agricultural activities in the nearby vineyards - Population increase in the abandoned agricultural area and small villages with no suitable urban infrastructure. - Development of tourism in the area protected by the Ramsar convention. - Implementation of the Water Framework Directive on the Dragonja catchment. - Since the river corridor areas are recreationally attractive (picnic areas, bathing, tracking), poor water quality may pose a risk to human health. - The greater part of the catchment area is proposed as a landscape park - The upper Dragonja River with its tributary, the Rokava, is protected as a natural memorial site. - The lowland section of the Dragonja River (in the local community Piran) is declared a natural protection site. - There are many localities that are protected as natural heritage sites. - Two thirds of the salt pan area at the mouth of the Dragonja River is protected as landscape park and declared a Ramsar natural heritage site. - Drinking water: (a) The area was an important drinking water supply for the Slovenian coast until 2001 (Buzini, Gabrijeli: satisfying 20% of the water demands); since the recharge area lies in Croatia and the water quality is unsatisfactory, the Slovene authorities stopped recharging the water and declared the springs as no long-term solution; as the agreement between Slovenia and Croatia has not been renewed, the Slovenian side is looking for supplementary water sources, (b) The area has potential for drinking water resource development (reservoir for storage of water pumped from other catchments). - Water for irrigation: a permanent conflict between use of water for irrigation and nature protection; the area has high potential for early summer market food production, but not enough water quantity potential; water is used for irrigation, but is not licensed (and no control is in force). - Floods: (a) As land owners are not in favour of flooding, conflicts between land owners and environmentalists have occurred, (b) The main transportation roads and facilities (customs and border police service) are still at a high risk of being flooded. 338 Mitja Brilly & Lidija Globevnik

- Maintenance of the Dragonja River channel, which is also the boundary between the two countries: (a) Permanent conflicts due to the different approaches to flood prevention: river banks are cleared regularly on the Croatian side but not on the Slovenian side (in the estuary the river was regulated four decades ago to control 20-year return period floods), (b) Maintenance of the Dragonja River: rehabilitation of the old mill channels and mill weirs is being considered, which may cause conflicts with the established land use along the river. - Land development in headwater areas for vine and olive oil production changes land-use patterns, attracts tourism, but also causes higher pollution loads and new water demands. - Hydrological drought periods are natural phenomena that are hardly considered by the various development plans (irrigation, wastewater treatment, drinking water supply, recreation, freshwater fauna protection). - If climate variability is high, the drinking water supplies are uncertain and needs for irrigation are hard to predict. As water users and the general public are hardly aware that climate variability is a natural phenomenon, they exert great pressure on water managers, expecting a stable water regime and all water demands to be met. - There is no drought management. - The River Dragonja is a basic natural resource for the cultural and economic development of the area due to its recreational, tourism and agiicultural development potentials.

SCIENTIFIC CONSIDERATIONS TO SUPPORT SUSTAINABLE WATER RESOURCES MANAGEMENT

The hydrological and land-use processes have been studied as an integrative issue in the EC PECO 1993 scientific research project (European Commission, 1996). In Globevnik et al. (1995, 1998), the re-vegetation processes that were studied for the 1971-1995 period, coupled with depopulation of the rural settlements at the same time, were first recognized as one of the most important clues to the changes in the existing erosion rates. Soil erosion has been reduced by more than half due to the changes in vegetation cover as well as to the anti-erosion measures implemented in ditches and eroded areas of hillslopes. At the same time, the hydrological regime changed (Globevnik & Sovinc, 1998). It has been shown that conversion of agricultural land to woodland and scrub has significantly influenced the hydrological regime of the main river. The reduced water yield and higher frequency of low discharges (analysed for the 1961-1995 period) were the most significant changes in the hydrological regime of the Dragonja River. Similar results (analysis for the 1961-2002 period) have been obtained by Keesstra & Dam (2002). Globevnik (1998, 2001) demonstrated that the hydrological changes have been coupled with changes in river morphology. It has been shown that the consequences of the 50% reduction of erosion since 1971 and a lower frequency of high water events are a reduction of the river's transport capacity and a subsequent bed load reduction by two thirds. Certain morphological changes were also observed at the river-bed level. Bed elevations have increased from 1.0 to 1.5 m in the upper parts of the river. Int the downstream section, there is hardly any bed load and few gravel bars exist. Sustainable water resources management in the Dragonja catchment, Slovenia 339

As already concluded in Globevnik (1998), the anti-erosion measures and reforestation of the area have considerable effects on the hydrological characteristics of the river. Geomorphic activity in the catchment is already limited due to the reduced flood magnitudes and sediment fluxes. Drought periods are longer and there is a trend recognized as less "blue water", which can be used for water supply and in turn sustain in-stream ecology. Changes in land use and implications for the hydrological regime thus need to be carefully considered and incorporated within the catchment manage­ ment plans. Further hydrological understanding is needed to recommend land manage­ ment strategies in the catchment and propose channel maintenance measures to retain water in the channel network and sustain river ecology.

PROPOSED ACTIONS TO SUPPORT SUSTAINABLE WATER MANAGEMENT

The actions to implement sustainable water resources management are grouped into three clusters. The first is an improved communication between water managers and the society, the second is enhanced scientific research, and the third a development of suitable innovative techniques. To improve communication, hydrologists, ecologists and geomorphologists working in the catchment should be able to: (a) provide adequate information on long- term and short-term impacts of a development on the society, when discussing develop­ ment plans, (b) predict trends of natural processes and human impacts on them, and (c) collaborate with the society in building strategies and making action plans. Therefore, a participatory network should be established and effectively organized to streamline the collaboration of the numerous interested parties (representatives of cities, natural and cultural heritage institutions, ministries and agencies responsible for environment protection, regional planning, water resources management, agriculture, forestry and food production, village communities, protected areas management boards, stakeholders and academics). Sustainable water management is everybody's business. Everybody should be informed about the impacts of their activities on the basin's water regime and environment. The impacts of bad practice and good practice should be well documented and presented based on practical examples in the catchment. To improve the scientific part, integrative research activities in the field of hydrology (catchment, forest, karst, ecology, sediment, Quaternary), erosion, channel morphology, water chemistry, water biota and landscape ecology are planned. The activities are already supported by educational and research programmes at the University of Ljubljana and Vrije Universiteit Amsterdam. Through special investig­ ations, erosion, geomorphology of the river bottom and catchment hydrology have already been studied in detail (Brilly et al, 2002; Globevnik, 2001; Keestra, 2002; Kessstra & Dam, 2002; Petkovsek, 2002). In the future, the Science and Research Centre , University of Zagreb and Hrvatske Vode will participate as well. The major innovative technique will be implementation of a web based interactive system that allows access to information and models, based on GIS technologies: http://nfp-si.eionet.eu.int/ewnsi/index.htm. When developing models and information systems, testing, and training of stakeholders, managers and students will be taken care of. 340 Mitja Brilly & Lidija Globevnik

CONCLUSIONS

If the planned activities are successfully performed and implemented, the web based decision support system will be developed. It is very important that, through a develop­ ment process, stakeholders, governmental organizations, non-governmental associa­ tions and other interested parties are involved. Therefore, meetings to discuss problems and concerns will be organized and a GIS information system with Internet access will be developed. At the same time, other supporting activities will take place: an "internet desk" for discussion and exchange of information will be opened. From the scientific point of view, a distributed eco-hydrological model should be developed and verified and field data should be regularly collected. To build a knowledge base, issues should be discussed all the time and verified with efficiently planned research activities. When operative, a decision support system on the Internet will help in keeping all interested parties informed and active. With this approach, sustainable water resources management in the context of the Dragonja River catchment action plan might be effectively formulated. A multidisciplinary approach in water management is a long- term issue and very time consuming. Proper management of personnel resources is sometimes even more important than the financial sources themselves.

REFERENCES

Brilly, M., Petkovsek, G., van Dam, O., Keesstra, S., Globevnik, L., Sraj, M. & Mikos, M. (2002) Experimental watershed of the Dragonja River (SW Slovenia). In: Interdisciplinary Approaches in Small Catchment Hydrology, Monitoring and Research (extended abstracts), 149-151. Slovak Committee for Hydrology, NC IMP UNESCO. Institute of Hydrology, Slovak Academy of Sciences, Bratislava, Slovakia. European Commission (1996) PECO 1993 - Project Summaries. Cooperation in Science and Technology with Central and Eastern European countries (CEEC) (cd. by A. Remond). ECSC-EC-EAEC, Brussels, Luxemburg. Globevnik, L, Fazarinc, R. & Sovinc, A. (1998) Land degradation and environmental changes in the Slovenian Submediterranean (The Dragonja River Catchment). Geodkodynamik XIX, 281-291. Bensheim. Globevnik, L. & Sovinc, A. (1998) The impact of catchment land use change on river Hows: the Dragonja River, Slovenia. In: Hydrology in a Changing Environment vol. I (ed. by II. Wheater & C. Kirby), 525-533. Wiley, Chichester, UK. Globevnik, L. (1998) Analysis of river morphological and environmental changes with the integration of historical data and image processing. In: Modelling Soil Erosion, Sediment Transport and Closely Related Hydrological Processes (ed. by W. Summer, E. Klaghofer & W. Zhang) (Proc. Vienna symp., July 1998), 279-285. IAHS Publ. no. 249. Globevnik, L. (2001) Celosten pristop k urejanju voda v povodjih. Doctoral Thesis, University of Ljubljana, Slovenia. Keesstra, S. D. (2002) Channel and flood plain response to reforestation in the Dragonja basin, southwestern Slovenia: linking past and present. In: The Structure, Function and Management Implications of Fluvial Sedimentary Systems (ed. by F. J. Dyer, M. C. Thorns & J. M. Oily) (Proc. Alice Springs svmp., September 2002), 185-194. IAHS Publ. no. 276. Keesstra, S. D. & Dam, O. (2002) Impact of reforestation on catchment hydrology in the Dragonja catchment, SW Slovenia. In: Palaeofloods, Historical Data, Climatic Variability: Applications in Flood Risk Assessment, PHEFRA (Proc. Barcelona Workshop, October 2002.) Krystufek, B., Gregori, J., Sivec, 1. & Horval, B. (1986) Invcntarizacija favne v dolini Dragonje. Prirodoslovni muzej Slovenije. Report. Ljubljana, Slovenia. Krizan, B. (2002) Naravna in kulturna dediscina doline Dragonje. Natural and cultural heritage of the Dragonja Valley. Varstvo narave (Nature Conservation) 19, 9-42. Ljubljana. MKPG (Ministry for Agriculture, Food and Forestry) (1998) Slovenia Irrigation Project, Feasibility Report no. 19 (Dragonja), AFC Bonn, Germany. Petkovsek, G. (2002) Kvantifikacija in modeliranje erozije tal z aplikacijo na povodju Dragonje (Quantification and modelling of soil erosion—application to Dragonja catchment, in Slovenian). Doctoral Thesis, University of Ljubljana, Slovenia. Vodnogospodarski institut (VGI) (2000) Vodnogospodarska osnova povodja Dragonje z Drnico. C- 924. Investor: MOP URSVN. Ljubljana, Slovenia. Wraber, T. (1987) Botaniëni utrinki iz doline Dragonje. Proteus 49 (6), 215-218.