Watershed Management: A Case Study of Umtrew River Basin, North East India Using Geospatial tools
ISBN 978-85-88783-11-9
Authors
1Deka, D.; 2Sharma, P.
1B.BOROOAH COLLEGE Email: dhanjeet.85@gmail.com
2COTTON COLLEGE Email: sharmapcc@gmail.com
Abstract
Watershed is defined as a topographically delineated geographical area in which the entire run-off tends to converged through the existing drainage system, to the common outlet of the area for subsequent disposal. In other words, a watershed is an independent drainage unit. This drainage unit is the most suitable geomorphologic unit for organization of all kinds of human activities and natural processes continuing within it. But due to increasing population pressure and unsustainable activities in the recent years deteriorate the environmental quality of the watersheds of the world in general and North East India in particular. Therefore it is necessary to study the drainage basin characteristics including evaluation of morphometric parameters using drainage map, contour map, ordering of streams, measurement of catchment area, perimeter, relative relief, relief ratio, length of streams, drainage density, drainage frequency, bifurcation ratio, texture ratio and also the monitoring of changing land use/land cover which further helps in management of the basin environment. North East India is a paradise of small and large rivers originated in the hills of their surroundings and debouched in to the mighty rivers Brahmaputra or Barak. So, the rivers of North East India experience the taste of both high hill environment as well as the plain environment for which most of the river basins or watersheds of northeast reflect the dynamic character controlled both by natural as well as anthropogenic processes. The hilly region which has unique geomorphological character shows different physical and natural environment, whereas the plain area depicts completely different condition controlled by anthropogenic phenomena. Remote Sensing together with Geographical Information System (GIS) has evolved as a major tool in the present era for planning, development and management of watershed as it provides synoptic view of the landscape, helps in evaluation of individual unit of watershed, analysis, modeling and decision support system. The Umtrew Basin is one of the important river basins of northeast India covering an area of 1253.1 sq km of which the upper and lower parts cover 1035.6 km2 and 217.5 km2 respectively. The upper portion of the catchment is mostly covered with grass and sparsely scattered trees. In the lower reaches, sub-tropical forests densely cover the catchment. Practically the entire basin lies in hills with flat narrow valleys. There are outcrops of rock at various locations of the riverbed. The upper regions of the catchment have a mild climate; temperature rising maximum to about 30°C and minimum to about 3°C. The winter season is dry during which frost occurs but no snowfall. The lower half of the basin can have maximum temperature of 35°C in summer season, while winter remains mild. Inspite of having suitable conditions for sustainable development, the Umtrew Basin is lack behind in many ways. Needless to say that in the present day context the said watershed is facing serious problems in various ways. Increasing biotic pressure like illegal felling of trees and uncontrolled grazing has devastated the hilly watershed. Simultaneously the population explosion has decimated the land and water resources. The introduction of agriculture and many other developmental activities represent a drastic change in land use pattern as a result of the removal of forest cover and altering the land surface condition in the Umtrew Basin. All these components form a complex and interactive system at different spatial and temporal scales and the results are ended at environmental change enhancing soil degradation, wetland shrinkage, mass wasting, siltation, flood, reservoir sedimentation and many other environmental problems in the study area. Looking at different aspects, the present study aims at evaluation of the characteristics of individual component of Umtrew River Basin with a goal in finding the way for sustainable watershed management. It involves the evaluation of morphometric analysis of the sub watersheds of Umtrew River as well as the changing pattern of land use/land cover for the last three decades of the said watershed using Remote Sensing, GIS and GPS techniques so that the data generated from the study will help in environmental management of the said watershed. As such this study will definitely help the planners, researchers and user communities in managing the other watersheds in the region.
Keywords
Watershed; Management; Geospatial