Assessment of Solar Photovoltaic Water Pumping of WASA Tube Wells for Irrigation in Quetta Valley Aquifer

This paper investigates the impact of tube wells on the discharge and water table of the Quetta Valley aquifer and conducts a financial analysis of the solar photovoltaic water pumping system (SPVWP) in comparison with a typical pumping system for the Water and Sanitation Agency of Quetta’s (WASA) tube wells. Quetta Valley is dependent on groundwater as surface resources are on decline and unpredictable. The population of this city has exponentially increased from 0.26 million in 1975 to 2.2 million in 2017 which has put a lot of pressure on the groundwater aquifer by installing more than 500 large capacity tube wells by WASA and Public Health Engineering (PHE) departments in addition to thousands of low-capacity private tube wells. The unprecedented running of these wells has resulted in drying of the historical Karez system, agricultural activities, and the sharp increase in power tariffs. There are 423 tube wells in operation installed by WASA in addition to PHE, Irrigation and Military Engineering Services (MES), which covers 60% of the city’s water demand. The results will be beneficial for organizations and positively impact the operation of these wells to meet public water demand. For the two zones, i.e., Zarghoon and Chiltan in Quetta Valley, recommendations are given for improved water management.

MAR site suitability mapping for arid–semiarid regions by remote data and combined approach: A case study from Balochistan, Pakistan

Climate change, along with the rapid increase in population and mismanagement of water resources, resulted in a decline in the quality and quantity of groundwater worldwide. Balochistan, the largest and driest province of Pakistan, is located in the south western part of the country. This region is suffering from the declining water table, land subsidence, and intense soil erosion. Rapidly increasing population, sea level rise, increasing temperature, declining average annual precipitation, and short-duration intense rainfalls with reduced percolation rates are further aggravating the situation. Managed Aquifer Recharge (MAR) is considered as a solution to reduce the stress on groundwater resources and achieve resilience to climate change. Creating a MAR suitability map may be one of the steps to be taken to reach sustainable groundwater management. This study produced the first MAR suitability map of the Quetta Valley, the most densely populated city of Balochistan, and Poralai and Hingol coastal basins suffering from seawater intrusion. To construct the MAR suitability map, the online INOWAS platform was first used to narrow down the suitable MAR options. Then, the six influencing factors including geology, slope, land-cover, precipitation, drainage density, and soil were identified, and the raster map of each factor was scored and weighted using GIS tools and the Multi Influencing Factor (MIF) method. All the factors were integrated according to their weight by using the ‘Weighted Overlay Analysis’ tool and the Multi-Criteria Decision Analysis (GIS-MCDA) in ArcGIS to produce the final MAR suitability map. The suitability map divided the study area into high, moderate, low, and very low suitability classes. The results depict that 80% of Poralai Basin, 10% of Hingol Basin and less than 5% of Quetta Valley falls in the high MAR suitability zone especially for trenches, ditches, furrows, and leaky dams. The first MAR suitability map for the basins of Balochistan can serve as the guidance and screening tool to focus site specific studies for highly suitable areas for MAR implementation. In the following phase of the study, an analysis of source, quality, and final use of water can serve to design and develop the specific MAR structures according to local conditions and needs. The displayed method is applicable to further MAR suitability studies for other arid-semiarid regions.

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

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.

Land subsidence caused by groundwater exploitation in Quetta and surrounding region, Pakistan

Land subsidence is effecting several metropolis in the developing as well as developed countries around the world such as Nagoya (Japan), Shanghai (China), Venice (Italy) and San Joaquin valley (United States). This phenomenon is attributed to natural as well as anthropogenic activities that include extensive groundwater withdrawals. Quetta which is facing similar subsidence phenomenon is the largest city of Balochistan province in Pakistan. This valley is mostly dry and ground water is the major source for domestic and agricultural consumption. The unplanned use of ground water resources has led to the deterioration of water quality and quantity in the Quetta valley. Water shortages in the region was further aggravated by the drought during (1998–2004) that affected the area forcing people to migrate from rural to urban areas. Refugees from the war torn neighboring Afghanistan also contributed to rapid increase in population of Quetta valley that has increased from 0.26 million in 1975 to 3.0 million in 2016. The objective of this study was to measure the land subsidence in Quetta valley and identify the effects of groundwater withdrawals on land subsidence. To achieve this goal, data from five Global Positioning System (GPS) stations in Quetta were acquired and processed. Furthermore the groundwater decline data from 41 observation wells during 2010 to 2015 were calculated and compared with the land deformation. The results of the GPS readings revealed that the land of Quetta valley is subsiding from 30 mm yr−1 on the flanks to 120 mm yr−1 in the central part. 1.5–5.0 m yr−1 of groundwater level drop was recorded in the area where the rate of subsidence is highest. Whereas 9–10 cm of subsidence was recorded in the surrounding areas of Quetta where agriculture and settlements are high. The surrounding areas include Kuchlak, Mastung, Pishin, Gulistan and Hurumzai districts. These results were acquired using InSAR imagery collected from October 2014 to march 2019. So the extensive groundwater withdrawals in Quetta valley and surrounding areas is considered to be the driving force behind land subsidence.