Daily Climate Extremes of Temperature and Precipitation Over Quetta Valley, Pakistan During 1961-2019

Abstract

Climate extremes are imperative to study the impacts of climate change that is significantly observed for the management of scarce water resources of the Quetta Valley. The daily data of temperature and precipitation are used to model the climate extreme indices for Quetta Meteorological Station from1961 to 2019. The statistical tests were performed by using Mann Kendal and Sen’s Slope method at the 95% confidence level. The overall change in minimum to maximum temperatures and precipitation-based climate extreme indices specify the frequencies of extreme events are increasing. That would cause heatwaves, gradual warming, steady dryness, and extreme precipitation events in the long term over the Quetta Valley. The minimum and maximum temperature-based indices inclusively indicate positive trends. That ultimately leads to a warming climate with a significant increase in summer as 5 days/decade, tropical nights as 5.3 days/decade, daily maximum as 0.28°C/decade, warm nights as 1.7 days/decade and warm days as 1.9 days/decade. For precipitation, all the indices show positive trends with a significant increase in consecutive wet days for 0.1 days/decade and an annual contribution of very wet days 0.8% per decade. The monthly increase in temperature and decrease in precipitation would increase the evaporative demands which may arise the water stress conditions over the valley and may put pressure over groundwater reservoirs.

GNSS and Sentinel-1 InSAR Integrated Long-Term Subsidence Monitoring in Quetta and Mastung Districts, Balochistan, Pakistan

“…The altitude of Quetta and Mastung is 1680 and 1650 m above mean sea level, respectively. Groundwater, which is only recharged by precipitation, is the only source for industrial, agricultural, and domestic use in Quetta and Mastung [41,42]. A total of 18 drought events have occurred in Quetta Valley from 1950 to 2010, with an average interval of 3.3 years.…”

“…The aquifer of the study area is under stress due to decades of mismanagement, droughts, and overexploitation of groundwater coupled with the population explosion. Currently, 2444 tube wells are operating in Quetta Valley, of which 494 have dried due to GWL decline [42]. The annual discharge and recharge of Quetta's aquifer system is 61.15 million m 3 and 97.65 million m 3 , respectively, resulting in a deficit of 36.5 million m 3 [43].…”

“…The groundwater level (GWL) in Quetta City has been declining at an alarming rate since the 1980s [40][41][42]60,61]. Oldham reported the first artesian well in Quetta Valley in 1892.…”