Clustering and Analyzing of Surface Water Droughts Severity and Duration (Case Study: Ilam Province)

Droughts event can be effect on available groundwater and water resources in the many components that it cause deficit. This purpose, for the deal with droughts hazard for make decisions it is necessary to monitoring and assessing droughts feature in point of view concluding severity, geographic extending. In this study the hydrological droughts analyzed based on the clustering, surface water index and moving average methods in the 6 selected hydrometric stations in Ilam province over the 1982-2011. The results of the SDI showed that only occurred the moderate and slightly droughts states for the 3 and 6 reference periods. In the 9 and 12 reference periods, additionally we observed the severity droughts states in the three past decade. All of the stations experienced one wet year severity droughts in over the 1991 to 1996 period in the three past three decade. In contrast, all of the stations had been in the hydrological droughts event in over the 1996 to 2006. Hydrometric stations classified in three clusters based on surface water drought statuses. The results of clustering showed that Ivan, Holeylan and Tangsazin stations labeled in cluster 1 and Nazarabad station in cluser 2 and finally the Sarjooi and Dartoot stations classified in cluster 3. Ultimately, The Mann-Kendall and Linear Regression were applied to explore the relationship between hydrological droughts and river flow trends. The results of the trends test showed that all of the stations had decreasing trends.