IWRA Proceedings

AbstractUnderstanding climatic changes by means of trend determination and study of major climatic parameters, particularly rainfall and temperature, and their comparison with records of climatic changes in the past can reveal patterns of changes. The present study investigates changes in climatic elements such as precipitation, maximum temperature and minimum temperature by Mann-Kendall model in Iran . Spatial comparison tables were prepared and the changeability of climatic elements were modeled on the basis of the region of highest changes in climatic elements and the zoning of climatic elements by geostatistic methods. Taking into account the significance of seasonal changes in Iran and the effect of the two seasons of spring and winter on the water resources of the country, changes arising from these two seasons were investigated. Then, using the Cokriging method, the relationship between these changing variables were defined on the basis of the regression model, and the relevant tests were conducted. The models obtained show that Iran should expect a climate which has not been experienced by her at least during the past 50,000 years, and that its changes are not separate from global climatic changes. Y = -0.59-0.01X (Precipitation changes in spring) Y = -0.382-0.02X (Precipitation changes in winter) Y = -0.797-0.007X (Minimum temperature changes in spring) Y = -0.607+0.019X (Minimum temperature changes in winter) Y = -0.782-0.016X (Maximum temperature changes in spring) Y = -0.479-0.04X (Maximum temperature changes in winter) As northwest Iran experiences higher climatic changes, Urmia Lake basin was investigated as the sample basin. ETM satellite images were used for reconnaissance of surfaces of changes and SRTM satellite images for determining the height of surfaces of changes arising from climatic change. The supervised classification was conducted on the basis of the sampling of lakeside surfaces, which clearly reveald the existence of four surfaces in the lake. Based on the studies conducted on these surfaces and the climatic changes concerned, it was concluded that each surface of the lake is proof of long-term climatic changes. Smaller and waterside surfaces indicate short-term climatic mutations and variations. Given the results of the study, it can be predicted that water resources in Iran will face more serious problems in a way that the natural strength of Iran to preserve and provide water resources will gradually subside. In other words, water resources in Iran will encounter waste through increase of floods and evaporations.