Opencast Coal Mining Induced Defaced Topography of Raniganj Coalfield in India - Remote Sensing and GIS Based Analysis

摘要

With the advent of mining activities at Raniganj coalfield in India, the natural topography has been defaced in some elongated tracts by either excavation or dumping. This paper deals with opencast mining induced defaced topography of Raniganj coalfield, which needs to be reclaimed properly right after mining. This paper investigated intensity of defacing topography, magnitude of topographic deformations through a number of ex-situ measurement. Consequences of these topographic deformations are also investigated in this study. Through a number of ex-situ measurement based on Geographical Information System (GIS) techniques, generating contour and profiling them over the spoil dumps and excavated lows using fine resolution digital elevation data (Remote Sensing image), a total 132 (85 are abandoned and 47 are working) patches of defaced topography have been identified, which covers 43.26 sq km. surface area. Some working opencast quarries are more than 95 m deep, with an area of more than 2.4 sq km and dumped ridges are more than 60 m high (peak), with area more than 1.5 sq km. In case of abandoned mine (more than 20 years) some quarries are more than 28 m deep with area 0.99 sq km. and some of dumped ridges are more than 28 m high (peak), with area 0.29 sq km. These kinds of defaced surface remain for a long time, such quarries contain acidic logged water and spoil dump leads to acid mine drainage and erosion of loose soil particle. It deteriorates the entire land, water system of the region. The study suggests restoring land right after mining and the area made to be ecologically conformable.