The Sultansazligi Wetland which is one of the most important bird paradise of Turkey, is placed at Develi Closed Basin within the boundary of Kayseri- Turkey. Sultansazligi is being protected according to the Ramsar Agreement. There is water scarcity and water pollution problem at Sultansazligi. In this monograph; the main reason of water scarcity is searched and the relationship between the surface water of Sultansazligi and groundwater is investigated. Electrical resistivity tests, isotope and water chemistry analysis are carried out for this aim. Former water chemistry analysis at Develi Closed Basin are also examined. Additionally groundwater budget of Develi Closed Basin and surface water budget of Sultansazligi are prepared. This study should help researchers and students dealing with wetland hydrology and isotope hydrogeology. Especially information given about isotope hydrogeology should be useful for the researchers and professionals.