TEMPERATURE AND RAINFALL VARIABILITY ON DROUGHT INDICES

Abstract

Drought is a climatic hazard that occurs all over the globe. The frequency of drought was increased by nearly a third all over the globe since 2000.The reason behind this disastrous climatic hazard is the sudden result of climate change that leads to water imbalance. In Pakistan, frequent drought events majorly occurred due to lack of rainfall that leads towards numerous adverse impacts on rain-fed areas. This research study was carried in Thal region of Pakistan to understand drought and to find impacts of drought on vegetation cover. Half of the Thal region is a semi-tropical sandy region that have extreme weather conditions. Annual rainfall is less than 200mm so it is prone to temperature conditions. The other half is in a semi-arid region of Pakistan, which experiences dry weather conditions. Meteorological and satellite data were used to identify drought years in the study area. The meteorological data for temperature and rainfall was obtained from Climatic Research Unit (CRU) and Climate Hazard Group Infrared Precipitation (CHIRPS). The monthly data of rainfall and temperature were used from the years 1981 to 2020 to identify drought years. Whereas satellite data was downloaded from MODIS Product i.e. MOD13A1.The indices that were calculated for vegetation drought indices were NDVI, DVI, STVI and EVI. Whereas aSPI, RDI, SPI and PET were calculated for meteorological drought indices. The study determined an overall change in vegetation cover due to variation precipitation and temperature data. From the analysis of vegetation and meteorological drought indices it was concluded that the years 2001 and 2002 were extreme drought years whereas the years from 2004 and 2006 were moderate drought years. The year of 2019-20 were non-drought years indicating healthy vegetation conditions in the study area. The Correlation among climatic parameters and vegetation drought indices were observed for drought, moderate and non-drought years. The analysis of correlation demonstrated that the variation in temperature and rainfall lead to an increase and decrease in drought indices values.