Trend analysis in turkish precipitation data and its impact on streamflows

Nowadays, trend analysis of hydrological variables comes into prominence by reason of climate change. The trend of hydrological time series can be determined by using parametric and nonparametric tests. The aim of this study is to investigate the statistical trend analysis of monthly and annual precipitation data (1932?2002) which were obtained from precipitation observation stations in Turkey on site specific basis by using Mann-Kendall, t-test and to determine trend of precipitation in 7 geographical region of Turkey by using recently developed statistical Region Mann-Kendall test. Furthermore these results compared with the afore regional trend analysis studies (1968?1997) on regional scale. According to the results, the precipitation, particularly in the winter months, decreased for the seven regions of Turkey. On the other hand, the precipitation, in the summer, spring and autumn months increased for the seven regions of Turkey. Regionally, the precipitation data decreased generally for South Eastern Anatolia region whereas other regions showed close numbers of increase and decrease. Moreover, the trend appeared in precipitation data did not influenced streamflows except for South Eastern Anatolia region. Keywords: Trend, Precipitation, Turkey, Mann-Kendall, Regional Mann-Kendall