Monitoring the Effects of Drought on Vegetation Cover and Groundwater Using MODIS Satellite Images and ANN
The main aim of present study was investigation on the effects of drought on vegetation cover and groundwater resources. In present study an available climatic data series (2001-2017) for 9 synoptic stations in Lorestan province were analyzed to detect wet and dry years by SPI. Also a long data series of MODIS data were analyzed by remote sensing data and the NDVI maps have been produced for study period (2001-2017). In addition the relationship between rainfall and groundwater level was investigated. Results of present study show that there is a direct significant correlation (R2=0.83) between SPI and the NDVI. In addition, results show that there is a significant correlation between groundwater level and three months ago precipitation at 95% confidence level. During study period 2008 and 2015 were selected as dry and wet years based on SPI values, respectively. The values of the NDVI in the wet year (2015) significantly are higher than the values in the dry year (2008) in 99% confidence level. Spatial variation of SPI show that for intensive drought conditions (2008) and wet year (2015) the north part of Lorestan province have the highest variation in compare with other parts of study area. Generally, the results of present study show that MODIS data in a mountainous area could be a key tool to detect effects of intensive droughts on natural vegetation cover, also groundwater level show a significant correlation with 3-months delay of monthly precipitation.