Présentations Colloques

Oral Presentation
8.05
Session 8.05: Karst aquifers
Zwahlen Franç
Impacts of intensive exploitation of the Jurassic-Cretaceous aquifer system on the organisation of the subsurface water flows (Syria)
The Orontes river basin, shared between Lebanon, Syria and Turkey, has the largest irrigated area around the Mediterranean. The first irrigated systems, set up on a large scale in the 1960s, were supplied directly from the river Orontes or from small dams built on it. In the 80s, the irrigated area has been greatly expanded through groundwater extracted from the vast karstified Jurassic and Cretaceous aquifer located upstream and central part of the basin.**Intensive exploitation of water resources of the basin has led to summer drying of the Orontes river and numerous springs in the 1990s. Multiple studies and several hydrogeological models were devoted to this situation, but many questions remain on how it came to be.**As part of a recent program of the Swiss Cooperation, the authors established a new hydrogeological map and several cross-sections of the basin. Referring to that map and to historical and recent flow rate data of springs and of the Orontes river, a piezometric map of the Jurassic and Cretaceous reservoir was created for the period prior to the development of irrigated areas, while in parallel, another piezometric map of the same reservoir showing two large groundwater drawdowns was drawn up, based on 2005-2006 data issued from a publication related to regional groundwater recharge.**The comparative study of these two maps provides a valuable basis for understanding the 1980s dramatic decrease in the flow of springs and of the river and the recent surprising increase in the flow of the same springs and of the river, result of the Syrian conflict. In the future, that study should significantly, as peace returns to the region, facilitate the necessary implementation of sustainable management of groundwater in the whole basin when the irrigation systems will be rebuilt.**
Switzerland