| 摘 要： |
In this study, we assessed the impacts of climate variations on streamflow in 28 near-natural catchments in Iran. To this end, we analysed the trend of annual streamflow, precipitation, and temperatures using the Mann-Kendall test and Sen's slope between water years 1982 and 2011. We evaluated the frequency of precipitation in different classes, i.e. below 5, 5-10, 10-15, and above 15 mm/day. Our results indicate a decline in streamflow at 25 catchments, at a rate of -5.66 to -0.19 mm/year. The annual precipitation amount did not decrease significantly, while the frequency of light precipitation events (<5 mm/day) increased. About 60% of the upward trend was significant. Mean temperature increased at all studied catchments, at an average rate of 0.055 degrees C/year. In short, our results indicate that increases in temperature and the frequency of light precipitation events are two leading factors in streamflow reduction across studied catchments. |
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