Impact of built environment on groundwater depletion in peshawar, pakistan

This paper attempts to explore the impact of built environment on the potential of groundwater infiltration in district Peshawar, Pakistan. In the study area, rapid increase in population together with inevitable urban expansion over the fertile agricultural land has been recorded, since 1980. During past four decades, major land use land cover changes have been recorded in infrastructural and housing sectors. In this study, state of the art tools and techniques of Remote Sensing (RS) and Geographical Information System (GIS) have been used to spatio-temporally analyze the changes in built-up environment and its possible impacts on infiltration and groundwater recharge. In Peshawar, groundwater is the sole source of water supply with more than 1,400 public tube wells having a total discharge of 8 million gallons/hour (8.41m³/sec). Besides these, private tube wells, hand pumps and dug wells are also supplying fresh water to fulfil the citizen's requirements. During 1981 to 2017, the population growth has augmented the demand and requirements of fresh water, which multiple times increased from 56 million liters/day to over 213 million liters/day. During the same period, the area under the built-up environment has also increased from 3.70 % of the total geographical area to 16.27 % and reduced the infiltration rate by 4 %. Such consistent increase in impermeable surfaces have depleted groundwater recharging rate from 108.75 millimeter/year (mm/y) in 1981 to 91.35 mm/y in 2014. In 2014, the abstraction of fresh water from ground sources was 105 mm/y, indicating high extraction and low recharging rate of groundwater from precipitation, resulting the depletion of groundwater sources and fluctuating the water table. The analysis at union council level revealed that falling of water table and drying up of tube wells have been observed and situation is quite alarming in the old city area. In some areas, the water table has been dropped down by more than 16 meters. Such consistent increase in the built-up environment and the resultant groundwater depletion need to be properly monitored so that its adverse impacts could be minimized.