Real time drought monitoring using Remote Sensing approaches A Case Study :Western desert of Kharga and Dakhla Regions

摘要

A new? drought index? was developed using Soil moisture(SM)? and Land Surface temperature (LST) reflectance data, which deduced from Landsat images, called ( LST/SM). This new index was examined beside other effective existing drought index named Perpendicular Drought Index( PDI), which consider? as useful indicator for? monitoring drought condition . These indices were applied on the middle of? western desert of Egypt ( Kharga and Dakhla regions ) as study areas. Red ,blue, and near- infrared? wavelengths of? landsat 8 (2014) and TM 5(2003) images were preprocessed First geo-registed then converted to TOA Reflectance for SM , PDI indices determination? Thermal? infrared bands were processed? using different algorithms? to deduce LST data . 800 random? points were well distributed? on each? resulted index? raster image to analyze? the drought condition. The results demonstrated? that for Kharga region the? mean? value for LST/SM index was slightly increased from 16.770 in 2003 to 16.807 in 2014,? and for PDI index ,the mean value increase? from 0.583 in 2003, to 0.6171 in 2014.For? Dakhla? region mean value? of LST/SM index? increase from 17.589 in 2003 to 20.820 in 2014 , while for? PDI? index , the mean value? increase? from 0.5676 in 2003? to 0.6021 in 2014. Standard deviation (SD )? for LST/SM index were? increased from 2.5933 in 2003 to 2.9775 in 2014? for Kharga region , and? SD increase from? 2.9996 in 2003?? to? 3.0756 in 2014 for? Dakhla region .? Analyzing the drought indices proof significant correlation? between LST/SM , PDI(r =.457). The results proof slightly increasing in drought condition? in the two study areas and this was agree with other previous field study. Finally These? indices? LST/SM and PDI have? the potential to provide? a effective, simple and real time monitoring method in the remote estimation of drought? phenomena.