Groundwater Potentiality in and around Jharia Coalfield using Geographic Information System
B. C. Sarkar
Department of Applied Geology,
Indian School of Mines,
Dhanbad, Jharkhand
bhabeshsarkar2005@gmail.com
S.Mukherjee
Department of Applied Geology,
Indian School of Mines,
Dhanbad, Jharkhand
Kalyan Saikia
Department of Applied Geology,
Indian School of Mines,
Dhanbad, Jharkhand
B Basu Roy
Department of Applied Geology,
Indian School of Mines,
Dhanbad, Jharkhand
P.R. Paul
Central Mine Planning and Design Institute,
Dhanbad, Jharkhand
Abstract
In the present study, delineation of potential groundwater zones in and around Jharia coalfield has been attempted following a multi-criteria evaluation GIS approach using Geomatica and SPANS software tools. Various data layers such as, litho-stratigraphy, drainage, lineament (fault), slope and water table elevation have been emphasized for delineation of groundwater potential zones owing to their relative importance in holding groundwater. A probability weighted approach has been applied for overlay analysis that allows for a linear combination of weights of each thematic map. The resultant map indicates buried river channels in the southwestern part of the coalfield flood plains and river channels near Damodar river are suitable groundwater potential zones. The southeastern part of the coalfield although considered suitable for groundwater zones but exhibits poor groundwater potentiality due to active mining activities in that part of the coalfield.
Introduction
Jharia coalfield is characterized by gently undulating to a rolling topography with an overall slope towards east-southeast. The average topographic slope varies in the range of 0.01% to 2.18 % and above. The ground elevation of the area generally varies from 240 m in the western part to 140 m in the southeastern part near the Damodar river (NRIMS, 1995). The entire area is subjected to denudational process. The different physiographic units of the area consist of hillocks and escarpments, pediplains, monad rocks, valley side slopes and valley flats. Vegetation cover is mainly sparse and degraded in nature. The important rock types exposed in the area include sandstone and shale of Gondwana Supergroup that lie unconformably over the Precambrian metamorphics.
In Jharia coalfield, the groundwater level is dependent mainly upon the presently existing topography, geomorphic features such as, abandoned channels, losing streams, etc. and human-induced recharge condition. Due to scarcity of drinking water and unhygienic condition around Jharia coal belt, the active population of the Jharia coalfield faces acute shortage of drinking water, which becomes even worse in the summer months. Some part of the coalfield faces water crisis so much so that the habitants use mine water discharge as potable water. Hence, there is a need for the groundwater potentiality mapping to delineate the potential groundwater zones. In this context, in the present study, an attempt has been made to evaluate different morphometric parameters of the Damodar river basin in around Jharia coalfield and delineation of suitable groundwater potential zones within the study area.
Methodology and Database
Thematic maps, viz. litho-stratigraphy, slope, drainage and lineament have been generated using Survey of India (SOI) topography maps, viz. 73 I/1, 73 I/2, 73 I/5, 73 I/6 in1:50,000 scale and Geological Survey of India (GSI) map of Jharia coalfield (Fox, 1930; revised by Mehta and Murthy,1957) in 1:63,360 scale. Ground truth has been collected on the litho-stratigraphic units through field various traverses. Dug well data are collected at different locations in and around the Jharia coalfield. Digital Elevation Model (DEM) of the study area has been generated from the topographic contours and bench marks. The elevation contour map has been generated from the DEM. These layers are generated in steps viz. digitization, editing, building topological structure and finally polygonization in SPANS Topographer software for GIS overlay analysis.
The database used for generation of various thematic layers include:
- Contour and spot height data collected from SOI Topographic maps viz. 73 I/1, 73 I/2, 73 I/5, and 73 I/6 in 1:50,000 scale;
- Litho-stratigraphic data collected from GSI map of Jharia coalfield (Fox, 1930; revised by Mehta and Murthy, 1957) in 1:63,360 scale;
- Lineament data collected from GSI map of Jharia coalfield (Fox, 1930; revised by Mehta and Murthy, 1957) in 1:63,360 scale and Central Mine Planning and Design Institute (CMPDI) map of Jharia coalfield in 1: 25,000 scale (Verma et al.1989) and;
- Dug well data collected by the authors from different networking stations in and around Jharia coalfield.
GIS Data Layer Generation
Digital elevation model (DEM)
Various thematic layers generated from the SOI Topographic maps, GSI map of Jharia coalfield, CMPDI map and from field data lead to creation of a DEM (Fig. 1) exhibiting spatial distribution of elevation continuously over a region in digital format. It has been generated by interpolation of bench marks, contours data collected from SOI Topographic maps. The contours at 20m intervals have been traced from the topographic maps and are digitized, edited and rasterised in the Geomatica software. The thematic layers are then generated through input of the data as point data with their respective Z-value field and then analysed through nonlinear interpolation. Ground elevation is taken as the Z-value field and the elevation contour map is obtained by contouring. The contour layer is generated through a Triangular Irregular Network (TIN) to the points. When a TIN is applied, the points are joined in a network of triangles with each point representing a vertex of a triangle. Each vertex of a triangle represents three values, viz. X, Y and Z. The X and Y values are the two dimensional locational values of the points. The Z-value is an attribute for point data, e.g. elevation, dug well data, etc. This procedure generates output in a quadtree data format.
Litho-stratigraphy
The litho-stratigraphic map of the area is generated from the GSI map of Jharia Coalfield. The different lithologies have been traced from the geological map and digitized as an area layer and then edited and this generated a thematic map in SPANS Topographer software. In Jharia coalfield Gondwana sediments (Talchir, Barakar, Barren Measure, and Raniganj formations) lie unconformably over the Precambrian metamorphics. The dominant lithologies include sandstone, shale and granite gneiss (basement rock). The litho-stratigraphic map of the study area is shown in Fig. 2.