MAPPING AGRICULTURE AND METEOROLOGICAL DROUGHTS USING MODIS AND CHIRPS SATELLITE DATA; A CASE STUDY OF RAINFED POTOHAR REGION, PAKISTAN

Abstract

The Potohar region lies in a semi-arid region of Pakistan, which often experiences dry weather conditions. The rainfall patterns are extremely erratic on a spatio-temporal scale during the Rabi cropping season. This research focused primarily on meteorological and agricultural droughts in the Potohar region. The study's major aims were to create a drought risk map for the study area, based on rainfall data (meteorological data) and vegetation indices. The agricultural and livestock productions provide the primary source of income in this region. Wheat is the most reliable crop grown in the area and it is planted in November and harvested in April in the majority of the region. Droughts caused by variations in rainfall have a negative impact on crop yield during the wheat season. The present study evaluates the change in vegetation cover due to variation in precipitation and temperature for the Rabi wheat crop for twenty years (2000 – 2020). The 6-month Standard Precipitation Index (SPI) showed that extreme drought conditions were observed from 2000 to 2003 for the wheat cropping season, with spatial variance in drought severity. Whereas, from 2006 to 2008, moderate agricultural drought conditions were experienced in all four districts (Potohar region), leaving a varied impact on crop health. From 2017 to 2020, no drought was indicated in all districts of the Potohar region, with high vegetation cover. Agricultural drought patterns and intensity were identified and evaluated using the MODIS products MOD09A1 and MOD11A2 with the help of different vegetation indices mainly Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Difference Vegetation Index (DVI), Difference Water Index (DWI), Difference Drought Index (DDI), Vegetation Health Index (VHI), Temperature Condition Index (TCI) and rainfall data across the Potohar region.vii The combined drought risk map delineates the drought prone sites by using weighted overlay analysis in Potohar region. Weighted overlay analysis is used to identify the susceptible drought prone locations with the help of vegetation indices (VIs). The results obtained from the combined Drought Risk map for twenty years (2000 – 2020) (Fig 4.39) shows that no drought conditions were seen in most areas of district Attock and Rawalpindi, whereas, lower areas of Attock and Rawalpindi experienced very slightly drought conditions. Similarly, the northern and south-eastern areas of Chakwal and Jhelum also experienced very slightly drought. Moderate drought was seen in southern to central parts of Chakwal and western areas of Jhelum. This data was further verified with the ground based rainfall data. Overall result shows that the change in rainfall patterns affects the vegetation health and cover. Policymakers can use the combined drought risk map as a tool to monitor drought risk areas and reduce the impact of drought on agricultural productivity. It also indicates areas where specific adaptation and mitigation are appropriate.