PIXEL SIZE EFFECTS ON DAM WATER STORAGE CAPACITY ESTIMATION USING GIS: CASE STUDY OF BUYUK KARACAY DAM, TURKEY

There are both, technical and operational. constraints to determine the suitable location and water storage capacity of a dam. as it requires extensive fieldwork by qualified technicians, followed by lengthy data analyses. To overcome these constraints, water storage capacity can be pre-estimated using Digital Elevation Model (DEM) which was generated from a digitized topographic map for any basin. In this study. the Buyuk Karacay Dam. located in Hatay province of Turkey was chosen for the case study. The water storage volume for the Buyuk Karacay Dam was estimated, using the DEM in GIS environment. Storage volume calculation procedures according to crest elevation of created virtual dam and topography were described. Maps of the stream network, stream order, and flooded areas were generated, using DEM in Ilwis 3.6 software. DEM having 10-, 20-, 30-, 40- and 50-meter pixel sizes, were used to calculate storage volume based on dam crest elevation which was 347 meters from sea level. The estimated volumes have been compared to determine pixel size effects on volume prediction, with results of the survey method which have been conducted after construction of Buyuk Karacay dam. Those results showed that 10-meter pixel size results in the best volume estimation. According to ten-meter pixel size. dam reservoir storage capacity was estimated 59.38 hm(3). This estimation is very close to the result of the survey method, which was 57.25 hm(3).