Shri S.K. Srivastav
Scientist ‘SE’ Geosciences Division, Indian Institute of Remote Sensing (NRSA), Dept. of Space, Govt. of India, Dehradun.
Shri Rizwan Ahmed
Junior Research Fellow, ISRO (Respond) Project, DAV (PG) College, Dehradun.
Dr. D. K. Mandal
Senior Lecturer, Dept. of Applied Geography, North Bengal University, Darjeeling.
The invention of Remote Sensing and GIS has opened new vistas in the field of geo scientific studies, viz. land form mapping, geological mapping, groundwater targeting. The use of aerial photographs and satellite imagery immemorial. The synoptic view provided by the satellite imagery helps in understanding and correlating various landforms, which cannot be readily observed from the ground due to limited range of observation. The last decade has seen a phenomenal growth in the use of Remote sensing and GIS technology in ground water studies as the ground water has become the most sought after natural resources by the mankind due to tremendous pressure on the ground water system by the ever-increasing population and individual growth.
Realizing the importance of Remote sensing and GIS technology the present study has been undertaken to study the geomorphology and delineates the prospective ground water sources in the Eastern Doon valley, and its surroundings falling in the newly formed state of Uttaranchal for this purpose, the satellite imagery (PAN and LISS III) provided by IRS have been digitally enhanced using various techniques to improve the visual interpretability. These enhanced images were visually interpreted to group different landform and geomorphic units existing in the area and to understand the process of their evolution other parameters which control the occurrence and movement of ground water, such as Lithology / Rock type, Structure Land use/Land-cover, drainage density were also interpreted using satellite imagery in conjunction with the existing maps and literature, and different overlays were prepared. Well data were collected from different government departments and analyzed. Based upon the well data, different maps like static water table map aquifer thickness map, will discharge map, well specific capacity map and well yield factor map were prepared.
Subsequently all the layers important from ground water occurrence and movement point of view were digitized and integrated in the GIS environment using index overlay method. The weights to different units/parameters and themes were assigned depending upon their importance. With this integrated GIS analysis, ground water prospects map of the study area was prepared. The ground water prospects have been classified quantitatively as excellent, very good, good, moderate and limited. The ground water prospective zone are essentially located in the intermountane Doon Valley area, especially in the lower part under semi confine to confine conditions. The denudo-structural hills of the Siwaliks and pre-tertiary rocks and residual hills of old Doon gravel’s from essentially the run off zone, wherein the prospects exists only along the valleys/topographic lows, suitable geological structures, springs and seepage zones.