Opencast Coal Mining Induced Degeneration of Streams: A GIS Based Study of the Raniganj Coalfield, India

Aims:Extraction of coal by the opencast (OC) method generates huge amounts of waste materials due to the removal of overlying rock and soil. These materials (overburden) are dumped near the mining site. Thus,anthropogenic landforms like mine pits, spoil dumps, and overburden dumps have been formed, which changes the topography of mining site. Rivers are affected by OC mines, as the alteration of topography disrupts the natural drainage system of the mining site, and the flow of rivers is largely affected. With this background, the objective of the present research work is to identify the nature and extent of stream degeneration by OC coal mining.Place and Duration of Study: The study areais the Raniganj coalfield (23°32’50”N-23°50’30” N and 86°39’49” E-87°16’41” E), which is situated in the Paschim Bardhaman District of West Bengal, and the Mugma area (Dhanbad District) of Jharkhand. Coal mining in the coalfield is regulated by Eastern Coalfield Limited or ECL. Methodology:Streams in the study area were identified from the Survey of India Topographical sheets (1: 50,000 scale) and OC mines were identified from Google Earth images (2016). Streamdegeneration was measured by superimposing streams and OC minesin a Geographical Information System (GIS) environment. Results:The study reveals that rapid growth of OC coal mines (total area of OC mines in 1990 was 26.15 sq.km. and 48.52 sq. km in 2016) within the Raniganj Coalfield degenerates the tributaries of the Ajoy, Damodar and Barakar Rivers in study area. Conclusions: Atotal of twenty eight catchment basins have been affected by OC coal mines and out of twenty eight, ten catchment basins have more than 90% degeneration. Thus, a sustainable management plan is needed to protect the environment and to maintain the riverine system of the study area.