Assessment of drought risk index using drought hazard and vulnerability indices

This study attempts to determine the spatial and temporal patterns of drought hazard and risk in Semnan province, Iran. Drought risk assessment has been conducted in eight counties of Semnan province using a conceptual framework which emphasizes on the combined role of hazard and vulnerability in defining droughts. The standardized precipitation index (SPI) at synoptic stations at 3 and 12-month time step for period 1985–2011 were used to provide drought hazard index (DHI) map using kriging interpolation and natural break methods by ArcGIS 9.3 software. Eight obtainable/quantifiable socioeconomic and physical indicators including population density, rural ratio, agricultural occupation, irrigated land, food production, and municipal, industrial, and agricultural water consumption were used to provide the map of drought vulnerability index (DVI). Finally, the map of drought risk index (DRI) was provided through the integration of DHI and DVI maps. The overall results showed that at 3-month timescale Shahroud and Damghan and at 12-month timescale Shahroud, Damghan, and Semnan are the most susceptible regions to drought in central Iran. Therefore, consideration of virtual water, cultivation of products with less water requirement and use of appropriate irrigation methods can be two important factors in water demand management which should be addressed by water resource managers.