Long-term trends in climate parameters and multiple indices for drought monitoring over Pakistan

Pakistan is facing extreme weather events like floods, droughts, heatwaves etc. for the last few decades. The variability of the climate parameters (temperature, precipitation, and evapotranspiration) is causing these extreme events and resulted in a lot of damage to infrastructure as well as the livelihood of people. To identify the future trends of these parameters, seasonal and annual trends were analyzed on the 60 observational stations from 1951 to 2019. Moreover, the variability of drought is also investigated by using multiple drought indices over different provinces of Pakistan. Non-parametric Mann–Kendall and Sen’s slope tests are utilized to estimate significance and magnitude in a trend of the meteorological parameters at a 95% confidence level. The results showed a remarkable increase in maximum temperature (0.008 °C/year) at Balochistan (0.019 °C/year), Azad Jammu Kashmir (0.010 °C/year), and Gilgit-Baltistan (0.011 °C/year). Similarly, a significant increase in the minimum temperature trend has been observed over Punjab, Sindh, and Balochistan, whereas a decrease over Gilgit-Baltistan (GB), Azad Jammu Kashmir (AJK), and Khyber Pakhtunkhwa (KP). A significant decrease in the evapotranspiration trend was observed over Punjab, while it was positive in Balochistan and AJK. Precipitation is significantly increasing during February and June, especially in KP (1.55 mm/year) and Punjab (2.45 mm/year). Also, drought indices trends were determined in different regions of the country by applying multiple drought indices namely standardized precipitation index, standardized precipitation evapotranspiration index, reconnaissance drought index, and deciles index. All the drought indices showed significant positive trends over Punjab and KP, whereas negative in AJK at 95% confidence level. The consensus of all drought indices indicated severe drought risk that occurred in 1952 and 2002. Moreover, all the drought indices show positive (wet) trends for Punjab and KP, whereas negative (dry) for AJK at a 95% significance level. These results provide useful information for developing drought adaptation measures for lower parts of Pakistan that may be more susceptible to drought in the future.