Drought Severity Zoning using Environmental and GIS Indicators

Drought is one of the environmental events and an integral part of climate change in any region and has significant effects. Due to the benefits of monitoring the combined climatic, hydrological, and agricultural conditions, vegetation indices (NDVI), land surface temperature index (LST), and standardized precipitation index (SPI) were used for analyzing drought intensity in Sistan and Balochestan province. To obtain NDVI and LST indices, MODIS satellite images were used in the months of growth seasons (September to October) from 2000 to 2019. Three stations of Iranshahr, Zahedan, and Zabol were selected to calculate the SPI index due to their long-term statistics (2000-2019), low statistical deficiencies, and appropriate distribution. A geographic Information System (GIS) was used to zoning the drought intensity. In this regard, after examining the types of interpolation models, the IDW method was used to prepare raster maps. Then, the obtained maps were classified from high to low SPI using the opinion of geography experts, and the drought zoning map was prepared. This study showed that the NDVI and LST indices experienced the highest intensity from 2008 to 2011 and the lowest intensity from 2003 to 2008, respectively. According to the SPI index, the trend of drought changes in the whole region in 2000-2006 and 2009-2014 is in the class close to moderate and high drought, respectively. The results indicate that the study area is sensitive to medium and short-term droughts. Most of the droughts occurring in this region are mild and moderate droughts, and drought is more likely to happen in the central and northern areas of the province.