EVALUATION OF GROUNDWATER RECHARGE CAPACITY THROUGH AN INVERT WELLS IN LAHORE CITY

Abstract

In Lahore city; due to rapid urbanization and high population growth rate, water demand has drastically increased for domestic, industrial and horticulture sectors. The water supply of the city is solely dependent on groundwater. The extensive extraction has resulted in the depletion of groundwater. The water-table depth varies from 17 to 42 m in the city. The water level in the city is decreasing at average rate of 0.92 m per annum (WASA Sources). Pakistan Council of Research in Water Resources (PCRWR) has installed an observation well in its office at Raiwind Road, Lahore and monitoring the water-table depth since 2004. Over the period of 12 years, water level has dropped about 9 m. The indiscriminate use of groundwater has resulted in groundwater depletion in many parts of the Pakistan, which accelerates the saline-water intrusion from the adjoining as well as from the underlying saline areas. In many parts of the world, rainwater is used to deal with water scarcity. Rainwater is an important source of recharging the groundwater aquifer. However, in Pakistan during rainy season huge amounts of fresh water is diverted into the drains where it mixes with the sewage. At many places, rainwater stays for considerable time and becomes a breeding ground for mosquitos resulting in outbreak of diseases. Recharge of aquifer through an inverted well is the most appropriate option of artificial recharge for industrial and urban areas, as it requires less space for whole system. PCRWR has installed six invert wells in Lahore city for groundwater recharge. Out of which, three boreholes were selected for this study to test the Recharge Capacity (RC) by putting water with water boozer. It was obvious that the invert wells installed in rich aquifer with filter depth of 16 m accepted to downturn the water at average rate of 35 m3/hour. While Estimated Recharge Capacity (ERC) is nearly 70 m3/hour. This ERC is calculated from an equation = 68 r*h driven from Darcy law =K 2 . Cumulative recharge of three wells was 1500 m3 from the total rainfall of 650 mm during the period of June 2017 to July 2018 with the catchment area of 5000 m2. It is approaching that study will offer considerable aid in sustenance and managing of groundwater resources in Lahore city.