GEOGRAPHICAL INFORMATION SYSTEM (GIS) LINKED EVALUATION OF THE GROUNDWATER POLLUTION AND ITS SOURCES AFFECTING ENVIRONMENT OF THE KARACHI CITY AND ITS COASTAL REGION

Azhar, Siddique (2006) GEOGRAPHICAL INFORMATION SYSTEM (GIS) LINKED EVALUATION OF THE GROUNDWATER POLLUTION AND ITS SOURCES AFFECTING ENVIRONMENT OF THE KARACHI CITY AND ITS COASTAL REGION. Doctoral thesis, University of Karachi.

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Abstract

In view of the shortages of water supply in Karachi City by the local authority, Karachi Water and Sewerage Board (KW&SB), a huge number of residents and even the industries have dug/drilled shallow wells almost all over the Karachi City. Preliminary investigations of individual sites identified highly polluted groundwater conditions. Realizing the acute environmental degradation conditions, first time a detailed geochemical study of groundwater entitled, "Geographical Information System (GIS) linked evaluation of the groundwater pollution and its sources affecting environment of the Karachi City and its coastal region" has been undertaken in the Karachi City. A total of 231 samples of groundwater from 18 localities and 88 samples of beach water and sediments from 9 locations from Karachi region have been collected on semi-grid pattern at about 1 km intervals. All the samples have been analyzed for heavy metals (Cd, Cr, Co, Cu, Pb, Ni, Mn, and Zn). Integration of the results of the present study with the demographic development and the hydrological parameters have revealed that the nature of urbanization and industrialization at different locations, infiltration of their effluent discharges, groundwater flow under the control of lithological and structural characteristics of the rocks, geomorphic features and beach slope conditions are among the salient factors for the uneven distribution of the toxic heavy metals in the subsurface and on the beaches within the Karachi region. Two main rivers Malir and Lyari and their smaller contributories are passing across the city. Most of the industrial estates are situated along these seasonal rivers. The industries and residential areas pour their effluents into the Malir and Lyari rivers and also into the contributories. These rivers provide infiltration of the polluted water into the groundwater as well as carry the effluents in the coastal areas of the Karachi region. The interactive correlation mechanism has identified the risk zones and pollution hot spots of individual heavy metals and their possible contributing sources. These sources are dominantly industrial estates established randomly within the City limits. Nature of the distribution of heavy metals in general and the pollution hot spots of different metals in particular appear to be controlled by the nature of industrial distribution. The results have also revealed the groundwater background values of each heavy metal for the Karachi region which could be utilized by the town planners and researchers as the baseline data for the future studies and/or planning. Based on the inferences drawn from the present GIS models, it is realized and consequently recommended to monitor the identified pollution hot spots. The monitoring would provide necessary actions to be taken for future mitigation options. The present study also identified several relevant studies to be under taken in future by the young researchers.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: geographical information system, groundwater pollution, karachi, coastal region, karachi water and sewerage board, environmental degradation, beach water, heavy metal, drainage, urbanization, industrialization, sanitation
Subjects: Q Science > QD Chemistry
Depositing User: Muhammad Khan Khan
Date Deposited: 26 Sep 2016 08:04
Last Modified: 26 Sep 2016 08:04
URI: http://eprints.hec.gov.pk/id/eprint/981

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