Rainfall and flow trend in Karkheh river basin

Hydro-meteorology parameters are sensitive to climate change. Therefore, it is important to investigate the present climate change pattern and its impact on water resources. Changes in a series may occur gradually or abruptly. Both of these changes could be detected by non parametric statistical tests. In this research, mean annual discharge flow and mean annual rainfall were selected for detection trends in Karkheh Watershed, one of the mountainous watersheds in Iran, using the Wilcoxon and Spearman rank correlation tests. Result showed that, both studied variables exhibit decreasing trend in the selected stations. But, no step changes were found in the time series. The observed trend in the upper area of the watershed may adversely affect the human activities of the region.