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Karst Landscapes

The term “karst” is applied to a specific geological landscape and morphology that develops wherever limestone formations, or other carbonatic rocks, constitute the bulk of the geological substratum of a region and outcrop over extensive areas. Due to their solubility, these rock formations develop high permeability along fractures and faults, with the formation of sinkholes, chasms, underground streams, and caves. “Karst” hydrogeology is hence characterized by very high fracture controlled heterogeneous permeability, almost total absence of surface drainage (which has been largely diverted into subterranean routes), high infiltration rates and rapid underground flows of groundwater.

Aerial shot

Karst reservoirs, or aquifers, contain large amounts of groundwater, and thanks to their high transmissibility can sustain substantial yields. They also support unique ecosystems very rich in biodiversity (in Croatia alone, karst ecosystems host 3,500 species of flora, 12 species of amphibians, 36 species of reptiles, 200 species of resident birds, 79 species of mammals, and 64 species of freshwater fish).

Karst aquifers and dependent ecosystems however are very fragile, and vulnerable to anthropogenic as well as climatic stresses. Any change in land use (Karst landscapes under natural conditions are normally densely forested), or in rainfall patterns will rapidly impact water quality, quantity, and even subterranean flows. Karst landscapes in fact represent in their entirety the recharge areas of the aquifer system, where rain water infiltrates rapidly through sinkholes and fractures, directly impacting groundwater quality, given the absence of a soil and/or fine sediment cover that may filter out contaminants and nutrients before they reach the groundwater table.

Karst aquifers are widespread globally: from Central America, to East Asia and to the Mediterranean region. They are often transboundary and generally contain very large freshwater resources. Their potential and characteristics are however little known, and the general lack of understanding of their vulnerability to land use patterns and water channelling/diversions are threatening their value and long-term sustainability.

The UNESCO International Hydrological Programme (IHP) is an intergovernmental scientific cooperative programme in water research, water resources management, education and capacity-building, and the only broadly-based science programme of the UN system in this area. IHP’s primary objectives are: to act as a vehicle through which Member States, cooperating professional and scientific organizations and individual experts can upgrade their knowledge of the water cycle, thereby increasing their capacity to better manage and develop their water resources to develop techniques, methodologies and approaches to better define hydrological phenomena to improve water management, locally and globally to act as a catalyst to stimulate cooperation and dialogue in water science and management to assess the sustainable development of vulnerable water resources, to serve as a platform for increasing awareness of global water issues. UNESCO’s Regional Office in Venice (BRESCE) is developing and implementing activities related to co-management of shared water resources in SEE at regional and national level.

Karst studies are part of the UNESCO Science Sector programmes (International Geoscience Programme, IGCP and International Hydrological Programme, IHP) since last three decades. Since 1972 UNESCO has coordinated and conducted a Global Study of Karst Aquifers and Water Resources and supported an array of international activities in the field of Karst Hydrogeology and Karst Water Resources Management in the region. Through these activities UNESCO was instrumental in increasing global understanding of karst hydrogeology and water resources challenges. In 2008 the International Research Centre on Karst was established in Guilin, China, under the auspices of UNESCO. The centre in China is the only international centre on interdisciplinary research on karst in the UN system and contributes to reach a better understanding of karst systems on a global scale, and to promote sustainable development in karst regions, which are generally regarded as one of the world’s most fragile environmental systems.  The Centre further provides advisory activities, technical information and training as a basis to develop and implement new integrated methods of rehabilitation and ecological restoration for karst regions.

The DIKTAS project aims at addressing the issue of the sustainable management of karst groundwater ecosystems. It focuses on one of the world’s largest karst geological provinces and aquifer systems: the karst region corresponding to the Dinaric mountain range, which runs from Friuli (NE Italy) through Slovenia, Croatia, Bosnia - Herzegovina, Montenegro, Albania. This region is still largely pristine, with large extensions of densely forested areas, viable populations of large carnivores, many thousands of caves, unique karst lakes (Ohrid, Prespa, Plitvice, Shkodra and many more) and abundant high yield and quality freshwater springs.

In most of the countries sharing the Dinaric Aquifer, karst freshwater constitutes by far the main source of drinking water. The dominant flow of the huge groundwater resources contained in the Dinaric Karst Aquifer System is towards the Adriatic and Ionian Seas, while the Eastern extension of the karst chain drains to the Sava river basin. The gradient is steep, over 1%, broken in a stepwise fashion by a series of karst depressions descending from well over 1000 m of altitude, down to 100-200 m asl, creating a very favourable environment for hydropower generation.

Groundwater eventually enters the coastal area through few rivers (Neretva, Cetina, Trebisnjica, and others) and more importantly through strong submarine groundwater flows that characterize the coastal areas of Istria and Dalmatia. The total amount of groundwater entering the coastal environment with its load of nutrients and other contaminants is not known, but certainly very large: it is estimated that karst groundwater is the largest source of freshwater entering the Adriatic Sea.

A number of initiatives aimed at facilitating freshwater related cooperation among the countries sharing the Dinaric Karst Aquifer System, have been launched with the support of bi- and multilateral donors.

The UNESCO/ISARM (Internationally Shared Aquifer Resources Management) project was launched in 2000 by the Intergovernmental Council of UNESCO-IHP. The Council also invited the Food and Agriculture Organization of the United Nations (FAO), the International Association of Hydrogeologists (IAH) and the United Nations Economic Commission for Europe (UNECE) to cooperate in order to create the inter-agency ISARM initiative to promote studies concerning transboundary aquifer systems. The UNESCO Chair/INWEB (International Network of Water-Environment Centres for the Balkans) in cooperation with UNESCO Venice Office (BRESCE) and the national IHP Committees implemented the ISARM programme in South Eastern Europe (SEE), including the Dinaric Karst Aquifer System. As a first step in improving the understanding of scientific, socio-economic, legal, institutional and environmental issues related to the management of transboundary aquifers, an inventory of shared aquifers in the region was developed. In cooperation with UNECE, 65 transboundary aquifers have been identified and a WEB based interactive meta-database was made available on the Internet to all interested parties, using the Google Earth technology.

Two major initiatives that were instrumental in creating consensus among countries on the DIKTAS project were also developed: the “Petersberg Process” on Transboundary Cooperation and Water Management in SEE, and the “Athens Declaration concerning Shared Water, Shared Future and Shared Knowledge” as well as the Process related to the Declaration.

The Petersberg Process was initiated in 1998 and is currently in its Phase II, jointly coordinated by the German Government and the World Bank.  The Process is intended to provide support to translate into action the current developments and opportunities for future cooperation on transboundary river, lake and groundwater management in South East Europe (SEE).

The “Athens Declaration concerning Shared Water, Shared Future and Shared Knowledge” started in 2003 and provides a framework for a long-term process to support cooperative activities for the management of shared water resources specifically in the SEE and Mediterranean regions. The Athens Declaration Process is intended to assist SEE countries, in cooperation with relevant stakeholders, to prepare IWRM and water efficiency plans for major river basins and lakes, including a range of complementary interventions, with a coordinated mechanism to allow for exchange of information and experience between activities.

In 2008 the IV International Symposium on Transboundary Waters, was held in Thessaloniki, Greece. The “Thessaloniki Statement”, which was formulated by the participants of the Symposium, summarizes recent challenges riparian countries face regarding transboundary surface and groundwater management and provides a guideline on how advantages from cooperation among countries can be maximized.

The Petersberg and Athens Declaration processes have been linked in order to generate synergies and maximize the outcomes for the benefit of the SEE region. The Process is jointly coordinated by the German Ministry for the Environment, the Hellenic Ministry and the World Bank. GEF IW:LEARN is supporting synergies and GWP-Med provides technical and administrative assistance. The Process would complement European Union (EU) integration processes, the Stabilization and Association process of the European Union and other ongoing initiatives in the region. It contributes directly to the scope and objectives of the Mediterranean Component of the EU Water Initiative (MED EUWI).

A number of other activities, which are directly related to the objectives of the DIKTAS project are ongoing in the region.

Other Notable Karst Areas on Global Scale


TDA is an assessment and prioritisation of transboundary water related issues of concern . It uses the best available verified scientific and technical information to examine the state of the environment and the root causes for its degradation. The analysis is carried out in a cross sectoral manner, focusing on transboundary problems without ignoring national concerns and priorities.

Click here for the DIKTAS TDA.

Click here for the TDA Summary.