On The Effects of Climate Change and Global Warming on Water Resources in Iran

In this paper, the effects of climate change on nationwide Iranian climate and water resources were investigated by a trend analysis of temperature, precipitation and river flow. The Mann-Kendal trend test was applied to the time series of monthly temperature and precipitation derived from satellite images. The mean monthly stream-flow data associated with representative stream gages of 6 major Iranian catchments was investigated for detecting any possible trend. Furthermore, the standardized precipitation index (SPI) was computed with the observed precipitation relative to 44 selected stations distributed throughout Iran. The results suggested a long-term increasing trend in temperature all over the country, while a statistically significant decreasing trend in precipitation was observed for north western and south eastern Iran. The results also suggested a decreasing trend in the available water resources across the country which is in agreement with the negative trend of satellite derived precipitation detected for some parts of the country. A decreasing trend was also observed in the SPI index indicating that the occurrence of severe/extreme long lasting droughts in some parts of the country might be attributed to the effects of climate change and global warming.