Historical and Future Climatological Drought Projections Over QuettaValley, Balochistan, Pakistan

Abstract

The historical climatological records provide eminent evidence that drought is a permanent natural disastrous phenomenon of Balochistan. The precipitation data from 1950 to 2010 characterized that 18 drought events flashed with an interval of 3.3 years when average precipitation deficiency ranges from 20 to >40%. The longest historical drought span over 1945 to 1955 and the most recent dry-spell extended from 1997 to 2003. During the last drought, the average precipitation values decreased from 0-21% in Balochistan, while in Quetta from 40-70%. The historical record depicts that drought study also identifies the future drought frequency and severity with return period over the time. Strong affiliationhas been recognized between the soil-moisture and standardized precipitation index, which ultimately helps to identify the spatial behavior of droughts.The Representative Concentration Pathways RCP4.5 and RCP8.5 were downscale at 25 km and 50 km, have been used for future behavior of meteorological parameters. The both RCPs show a positiveincreasing trend for mean temperature and a negativetrend for precipitation for the 21st century. A significant increase in temperature has observed 0.04 °C/y and 0.12 °C/y at RCP4.5 and 8.5 over Quetta Valley respectively. The precipitation values represent no significant change in trend observed at 95% confidence level for the century. A marginally declining trend is identified by the statistical tests in precipitation. The precipitation and mean temperature data have been downscaled for midcentury 2040-2069 and far future 2071-2100 using different Regional Climate Models, namely ERA-40, ECHAM5 and fvGCM to identify association with the observational data of Quetta Valley. The observational data of mean temperature and precipitation shows a strong correlation to the downscaled data of ERA-40 as R2 = 0.97 and R2 = 0.47 respectively. The ERA-40 exhibits somewhat underestimate the mean temperature and overestimate the precipitation data. The observational data used to calibrate the downscaled data.The variability in temperature and precipitation has an enormous social and economic impact on the residents of Quetta Valley. The climatological variability devastated the ecosystem, depleted the groundwater resources and exhausted environment. The study outcome assists different stakeholders to predictand device immediate, short and long-term strategies to combat droughts. The Water Resource Managers and Planners may develop preeminent future “Drought Mitigation Policy” in the light of climate change over the Quetta Valley.