DIGITAL ELEVATION MODELING USING ILWIS 2.1 IN PARTS OF PURULIA DISTRICT, WEST BENGAL, INDIA

摘要

The quest for the discovery of natural resources like groundwater, mineral resources, petroleum resources etc. have been going on since the dawn of civilization by using various available techniques. The recent technological development in the field of computer science has made the methods of discovery of natural resources and interpretation of data more interesting. Remote Sensing Technique and Geographic Information System (GIS) software provide a quick approach in the analysis and interpretation of data for an efficient management of earth's natural processes, like natural disaster management, coastal zone management (CZM), environmental impact analysis (EIA), etc. The present study is an initialization of the above techniques for management of earth's natural resources. The study area is part of the Purulia District of West Bengal (Lat. 23 deg 05' to 23 deg 10' N and Long. 86 deg 00' to 86 deg 10' E; SOI toposheet no. 73 I/4) and is characterized by undulatory topography with rugged hilly terrain. The hilly terrain is mostly covered with forest while the plains are mainly barren or covered with grassland/ cropland and few villages. The area is mostly covered with Precambrian rocks (Granite Gneiss and Mica-Schist). Scattered occurrences of amphibolite and quartz veins are also noticed in the northern part of the study area. Digital Elevation Model (DEM) forms an important component of any GIS analysis and interpretation. The interpolation of contour lines is the most popular technique as they are the most easily accessible geomorphic data of elevation. DEM has been prepared with help of ILWIS 2.1. Digital Elevation Model has a wide application and forms one of the main inputs in many GIS projects. It is also the basis for a large number of derivative informations. Slope map forms an important component of a GIS related analysis and interpretation. Slope angle or slope percent in X and Y direction have been calculated using a DEM, gradient filters (DFDX, DFDY) and an equation of slope calculation. Similar to the slope map, the slope direction (aspect) map is also an important component in any GIS application. The aspect map has been calculated by combining the gradient maps, resulting from the application of the horizontal and vertical filters on a DEM. The slope map and slope aspect map prepared from the DEM by using gradient filters of ILWIS 2.1 can be utilized very effectively in any GIS application.