Department of Civil Engineering, Engineering Faculty, Ege University, 35100, _Izmir, Turkey
The present study aims to determine the hydrological change-year by evaluating the homogeneity of average annual stream flow data in Turkey. Pertaining to the years 1936-2005, change-year stream flow data from 74 stream flow gauging stations, which have no regulatory structure on the source side, and possessing a minimum of 39 years of data, from stream flow gauging stations located on 26 stream flow basins in Turkey, have been collected. By using the employed homogeneity tests, it has been attempted to detect the change year. Employed methods are the Buishand test, the Pettitt test, the Standard Normal Homogeneity test and the Von Neumann test. By comparing the results obtained from tests, it is aimed to detect the consistency of the change years in gauging stations. The change year could be detected in 16 gauging stations using three tests each every year, and 18 stations using 2 tests in the same year. It has also been ascertained that change years of stream flow are geographically closer to each other in western Turkey in comparison to the east. The reason for values in the west to be closer, with respect to both location and time, might be attributed to the precipitation characteristics and uniformity of measured data.