Spatio-temporal Analysis of Dry and Wet Years with the Purpose of the Recognition of Moisture Fluctuation Susceptibility of Sarab Plain Using MFI Index and GIS Models

The aim of the present research is the use of MFI (moisture fluctuation index) with the purpose of determining moisture fluctuation susceptibility and its comparison with the existing land uses in GIS environment (geographic information systems). By so doing the susceptible land uses for probable droughts in Sarab Plain could be specified. At first monthly precipitation records of the existing stations in Sarab plain were studied through SPI (as a standard index) for the statistical period, and the year 1379-80 was specified as the driest year while year 1383-84 as the wettest one. The data obtained were transferred into the GIS software and finally, we interpolated land cover susceptibility inside the GIS. Followed by this, the appraisal of susceptibility of ground surface versus the precipitation element fluctuations was modeled by mathematical models. With the utilization of satellite images of ETM+ (drought) and SPOT (wet years) the vegetation cover index of NDVI of the region was prepared for the years of study. With the provision of land use map of the area (dry farming, irrigation, urban points, rangelands, etc.) and the comparison of it with the zoned map the moisture fluctuation index of Sarab plain and the effectiveness pattern of the type of land use of the region from drought occurrence were determined in the course of spatial analyses in GIS. Based on the results acquired, agricultural productions of dry farming in west of Sarab were categorized in the first grade and the agricultural productions of irrigated lands in the middle and finally the horticultural products in the next stage were most affected by moisture fluctuations.