Effect of Irrigation System on Groundwater Resources in Harran Plain (Southeastern Turkey)

Irrigated agriculture is the largest consumer of groundwater resources. The interaction between agricultural irrigation and groundwater resources, both in quantity and quality, is often understood later than when the adverse effects starts. For more efficient and sustainable utilization of the limited water resources, improved understanding of how respond to irrigation is essential. The Southeastern Anatolia Project (Turkish: GAP) is a major and comprehensive initiative in Turkey. The GAP was a programme to develop water and land resources in the region and planned as a package that comprised 13 individual projects on irrigation and energy production on the Euphrates-Tigris basins. This project includes irrigation networks for an area of approximately 1.8 million hectares. One of the important project sites is Harran Plain having the biggest groundwater resources and the largest irrigation field in the GAP region. Harran Plain has 3,700 km² drainage area, 1,500 km² plain area and 476,000 hectares of irrigation area. Before this project, the irrigations could potentially lead to about 2 m/year decline in groundwater table. After this project application, hydrodynamic system of groundwater has changed. The groundwater level has risen since 1995 in plain. In addition hydrodynamic system has been effected groundwater quality. Results show that a proper irrigation rotation system can implement an efficient water management over the irrigated areas and lead smaller groundwater change and its quality.