Drought is a continuous process in Thar Desert Pakistan. It is required to assess the extent of this drought for future land use and adaptation. The effect of previous drought was studied on vegetation cover of Thar area, through combined use of drought indices and geographic information (GIS) techniques. Five years (2002, 2005, 2008, 2011 and 2014) were selected to analyze the drought conditions and land use pattern of Thar area. The drought indices used in this study included Normalized Difference Vegetation Index (NDVI) and Standard Precipitation Index (SPI). Images of past drought were compared with post drought images of our targeted area and land use maps were developed for spatio-temporal analysis. Data obtained from satellite images of drought and post drought time periods were analyzed so as to access the changes occurred in land use and vegetation cover through hybrid (digital and visual) interpretation techniques. The results of the study revealed that vegetation in Thar showed an improving trend from 2002 to 2011 and then again began declining from 2011 till 2014. The rainfall occurred at below average rate and SPI values for each year were calculated to be negative, indicating below average rainfall. This actual precipitation data was then compared with the data obtained from TRMM satellite and R2 as well as Pearson correlation coefficients were calculated. The R2 values for the years 2002 & 2014 were 0.519 and 0.670 respectively. In the same manner, the values of Pearson correlation coefficient for the years 2002 & 2014 were 0.721 & 0.867 respectively. The results showed TRMM satellite’s over-estimation in calculating rainfall data. Further, average temperature for five years under study was analyzed by graphical representation and it was revealed that temperature of Thar has increased by almost 1oC during the last decade.
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SPATIAL DROUGHT MONITORING IN THAR DESERT USING SATELLITE BASED DROUGHT INDICES AND GEO-INFORMATICS TECHNIQUES
Published: 16 November 2017 by MDPI in 2nd International Electronic Conference on Water Sciences (ECWS-2) session Climate Change and Marine Ecosystems