Climate Change Monitoring In Terms Of Drought Indices in Pakistan

Abstract

Pakistan, a resource-stressed country highly vulnerable to the adverse impacts of droughts, faces challenges in adequately monitoring climate variations due to sparse network of ground-based gauge stations. However, these challenges can be addressed by leveraging climate model-based spatially continuous datasets for monitoring climate parameters. This study aims to first evaluate the performance accuracy of a reanalysis dataset (ERA5-Land) by comparing it with observed precipitation and temperature data acquired from Pakistan Meteorological Department (PMD) and subsequently utilize ERA5-Land data to calculate drought indices for monitoring drought conditions across the country. ERA5-Land showed promising accuracy in following the fluctuation patterns of monthly observed precipitation and temperature. Statistically, it displayed low bias; acceptable values of correlation coefficient and RMSE for both temperature and precipitation. Monthly observed anomaly time series of precipitation and temperature were well-matched by ERA5-Land, indicating the potential of ERA5-Land to be used in drought monitoring studies. The major output of the study were the maps and time series depicting the current and past drought conditions in the country. Historical decadal spatial plots for 6-monthly SPI and SPEI depict some obviously expected hotspots over Baluchistan while there are scattered drought trends over North-Western regions of Pakistan as well, indicating the decrease in precipitation and increase in temperature in those regions. Timeseries plots for SPI and SPEI over some of the hotspots indicate an overall increasing susceptibility of Awaran, Multan, Thatta, and Risalpur to meteorological droughts. The findings of this study hold significant value for various stakeholders and target sectors including researchers studying climate change impacts, water resource management sectors, and water and power regulatory authorities as well as the organizations tasked with handling natural calamities such as NDMA and PDMAs. Furthermore, a drought monitor has been devised for SPI-6 and SPEI-6 providing monthly assessments of drought condition of the country. Concerned stakeholders could maintain an archive of these maps providing a valuable resource for monitoring and managing drought. The procedures and layout of this work are general in terms and can be replicated at the national or regional level, and also provide vistas for calculation of more enhanced and modern drought indices requiring varied input variables.