Impact of climate change on annual stream and sediment flows (Case study: Karaj River basin)

The present study investigated changes in annual precipitation, stream and sediment flows inKaraj River basin, under the phenomenon of climate change, during Statistical period of 1968-2008. In this review, the average rainfall and the annual stream and sediment flows of twostations which are located in the upstream and downstream of Karaj dam and hold long- termdata that are appropriated for the present study were chosen and the data were studied by Mann-Kendall test and regression analysis. The results of Mann – Kendall test were confirmed adownward trend in rainfall data during recent decades. The results showed that the stream andsediment flows in two stations during a four-decade have had a trend of decline and Mann –Kendall test results have proven the significance of this trend. Results of the present studyconfirm the decreasing trend in surface water resources in Karaj River basin under the effect ofclimate change and can be used in management programs and exploitation of water resources.

Keywords:

climate change , stream flow , sediment discharge , Karaj River basin , Mann-Kendall test