Drought is an extended period of low precipitation which resulted in injuries to consumers of water, especially in the agricultural sector and reduces there performance. Drought phenomenon including disasters that should not be expected to be seen. According to different reasons this incident with other natural disasters such as flood, earthquake, hurricane, etc. First, drought starts slowly and gradually and its impact in a relatively long period of time in different parts of the water resources, agriculture, social, economic and environmental issues appear. Second determining the exact start and end time of drought is partly difficult that due to this feature often describe drought creeping phenomenon. Different indices such as SPI, PDSI, and SWSI for evaluating drought are suggested, that based on a variety of meteorological, hydrological and agricultural drought. Since each index is intended to encompass all factors, not identified. This study has been carried out for defining an integrated index including main factors of drought and applied to the Zayandehrood river basin in the central Iran plateau as study area. An integrated index includes various factors such as meteorological, hydrological, agricultural, socio - economic and environmental drought. Climate change during this basin is very eye-catching, while Chelgerd area at the west side of the basin has more than 1400 mm of rainfall per year; at the east side of the basin the annual precipitation does not exceed more than 100 mm. Due to continues droughts at recent decade, this area has been chosen as a case study. In designing of integrated index, we have used combination of static and dynamic layers. Static layers including land use, slope and soil type. Dynamic layers including precipitation, evaporation, temperature, surface water storage, groundwater levels, and environmental needs. All static and dynamic layers representing spatial maps of different factors were prepared and compiled using Arc- GIS software. Each of static and dynamic factors has been categorized in to various sub- justify; LINE-HEIGHT: normal; MARGIN: 0in 0in 0pt; unicode-bidi: embed; DIRECTION: ltr" dir=ltr Keywords: Drought vulnerability, Integrated Index, Monitoring, Zayanderood River Basin
