GIS BASED GROUNDWATER QUALITY INDEXING IN LAHORE RESIDENCE, PAKISTAN. |
Paper ID : 1077-SMPR-FULL |
Authors: |
Khalid Mahmood *1, Mahammad Asim2, Zia Ul-Haq3 1Department of Space Science, U 2Department of Space Science, University of the Punjab, Pakistan 3Remote Sensing and GIS Group, Department of Space Science, University of the Punjab, Lahore, Pakistan |
Abstract: |
Groundwater is the most suitable fresh water for drinking as it contained almost balanced salt concentration, which is good for human use. Owing to its unique characteristics such as hydrogen bonding and polarity, water has the ability to dissolve or suspend many components which leads to its contamination. A comprehensive groundwater quality study in context of its spatial distribution had been conducted for residential area of Lahore, Pakistan. The mega city is facing serious challenges for the provision of safe and sufficient drinking water and the situation is predicted to be get more severe in coming days. The study had made use of the geographic information system (GIS) for geographical representation and spatial analysis of groundwater quality. 73 water samples had been analysed for physio-chemical parameters including TDS, pH, Cl, Mg, HCO3, Alkalanity, Electric Conductivity and Ca using standard methods. Water quality Data had been geo-referenced using GPSmap-76CSx receiver that had an accuracy of 3m in measuring horizontal coordinates of position. Boundry of the residential area of Lahore is marked/digitized using Quick Bird data having resolution of 2.6m, improved to 0.6m through high resolution merging. Each of the parameter is interpolated to generate their indvidual continously varying raster layers using Inverse Distance Weighted (IDW). Some of the parameters including alkalinity and bi-carbonates were showing unusually high values in most parts of the study area. To overcome problem of diversity in values all the rasters had been classsified into three classes as per WHO guidlines. Finally the Quality Index Map is prepared by Weighted Overlay Analysis (WOA), with maximum weight of 28, assigned to TDS. Weights, showing relative importance, assigned to pH, Cl, Mg, HCO3, Alkalanity, Electric Conductivity and Ca are 16, 8, 8, 9, 12, 12 and 8 respectively. The Quality Index map is classified into five zones of Excellent, Good, Poor, Very Poor and Unfit for drinking standards of drinking water. 21% region has excellent quality and 50% is found in the region of good water quality and is mostly found in the northern parts of the study area. Poor quality groundwater, with a share of 27%, is found mostly in south eastern parts of the study area however its patches are also found in Anarkali, Misri Shah and Furrakabad subdivisions. Only 2% of the area had been found under the very poor and unfit water quality conditions for drinking. The hotspot that is classified as unfit for drinking is found at the same region, which is widely stated to be having the deepest groundwater levels in the Lahore. The same region is found prominent in most of the individual parameters maps (TDS, HCO3, EC and Alkalinity) for their high values. Spatial distribution of the water quality index somehow relates the unfitness to the lateral flow of the groundwater. This lateral flow is a result of the abandoned localized recharge due to cemented construction in residential areas and high abstraction of the water from a long time. The scenario requires people awareness plans to stop unnecessary wastage of this precious fresh water resource for the sustainable development of the Mega city of Lahore. |
Keywords: |
Drinking Water Quality; Groundwater; Water Quality Index; GIS; Spatial Distribution |
Status : Paper Accepted (Oral Presentation) |