|
GIS based correlation between groundwater quality parameters and geological units
 S. D. Dhiman Research Scholar dhimansanjay18@hotmail.com  A. K. Keshari Assistant Professor, Department of Civil Engineering Indian Institute of Technology Delhi, Hauz Khas, New Delhi akeshari@hotmail.com
Abstract The increasing amount of multiple data sets being made available from various sources has created a need for efficient capture, storage, management, retrieval and analysis of geoenvironmental data to address various groundwater pollution problems of varying nature, dimension and complexity, cropping at local, regional and basin scale worldwide. Geographic Information System (GIS) has emerged as an effective tool for relating and integrating vast volumes of different data types, obtained from different sources and compiled on different scales. In this paper, a methodology is presented that utilises GIS to quantify the spatial geologic data and statistical analysis to determine the relation between groundwater quality parameters and geological units. The methodology is illustrated through an application to a study area located in the Western Indian Aquifer (WIA) system. The areal extents of geologic units in the study area are identified and their spatial distributions are quantified using GIS. The spatial extents of identified geological units are then correlated with the groundwater quality parameters using statistical analysis. Results reveal that there is a high negative correlation between calcium and ultrabasic rock, a high positive correlation between fluoride and ultrabasic rock, a moderately high positive correlation between bicarbonate and ultrabasic rock, and a very high positive correlation between pH, gneiss and schists. Such studies within GIS environment help in better understanding of the water-rock interactions, and thus will prove useful in formulating numerical models to study transport mechanisms of various chemical species in different hydrogeologic and chemical environments. Introduction Rajasthan is situated in the western part of Indian subcontinent. The Dungarpur district is located in the southern part of Rajasthan between 23020' and 24001' north latitude and 73021' and 74023' east longitude. In the west, it has common border with Gujarat. The total area of the district is 3770 square kilometers. In the north and east, the landscape is rugged and wild, but towards southwest border, the features seem to merge in the topography of Gujarat region. The eastern portion slopes down towards the basin of Mahi. The rugged and wild aspect of the region is attributed to the offshoots of the Arravalli’s. Two perennial rivers viz., Mahi and Som flow through the district. The Mahi separates the district from Banaswara, and Som forms a natural boundary with Udaipur district. The non- perennial streams are Jakham, Majhan, Vatrak, Bhader, Gangli, Sapan and VeriGanga. The water table in the district varies from 5 to 15 meters below ground level. The normal annual rainfall in the district is about 761.7 mm. The district has a dry climate with hot season milder than in the desert region of Rajasthan. The maximum temperature in summer is about 380 C and minimum temperature in winter is about 90 C. The geological system of the district belongs to the Pre-Cambrian Aravalli system. Slates are in abundance in the central region and are largely identified with veins of quartz particularly in the area north and east of Dungarpur town. Some patches of pegmatite and granite intrusions may also be found in the slates. The ultrabasic rocks have been observed as potential sources of asbestos, chromite, magnesite and talc. Among minerals, fluorite, beryl, asbestos and soapstone are the main ones. Besides, copper, mica, kyanite and lead ores have also been found. The study area for GIS based correlation between groundwater quality parameters and geological units falls between 230 41’ and 240 north latitude and 730 45’ and 740-east longitude. The geological information for the study area has been taken from the work done by Gupta and Mukherjee (1938) and the hydrogeological conditions are based on the investigations carried out by Jethra (1998) for the Dungarpur district of Rajasthan.
Page 1 of 3
| Next | |