Prioritization of Sub-watersheds in Khanapara–Bornihat Area of Assam–Meghalaya (India) Based on Land Use and Slope Analysis Using Remote Sensing and GIS

Improper utilization of natural resources without any conservation work is the prime cause of the watershed deterioration. Fast developmental activities and population pressure in the hills of Khanapara?CBornihat area near Guwahati city (about 10?km east of Guwahati) results rapid alteration of the land use/land cover in the recent times. This also causes the growth of land use over the unsuitable topography. As a result, there is a general degradation of the natural resources within the area. So, urgent measures have to be adopted to take up the conservation measure for the management of natural resources. Watershed wise conservation is considered to be the most acceptable and convenient approach. In the context of watershed management, watershed prioritization gained importance in natural resource management. The present study makes an attempt to prioritize the sub-watersheds for adopting the conservation measure. The prioritization is based on land use and slope analysis using Remote Sensing and GIS techniques in Khanapara?CBornihat area of Assam and Meghalaya state (India). The study area of 323.17?sq. km is divided into three 5th order, four 4th order and two 3rd order sub-watersheds. Land use/Land cover change analysis of the sub-watersheds has been carried out using multi temporal data of SOI toposheets of 1972 and IRS LISS III imagery of 2006. The study shows the significance changes in land use pattern especially in settlement and forest lands from 1972 to 2006. Slope map of the sub-watersheds prepared from the contour values in the toposheets show the wide variation of slope in the area ranging from 0° to 87°. Based on the extent/nature of land use/land cover changes over time and land use/land cover??slope relationship analysis, the sub-watersheds are classified into three categories as high, medium and low in terms of priority for conservation and management of natural resources.     

Predicting the Impact of Coastal Development on Water Quality Using Remote Sensing and GIS‐assisted Hydrologic Modeling Techniques

Abstract

A decline in water quality in the Okatie River, a coastal estuary located in Beaufort County, SC, has resulted in the closure of several shellfish beds. Continuing urban development within the watershed has altered land cover conditions and may be contributing to the recent decline in water quality. Remote sensing and geographic information system (GIS) technology, coupled with a water quality model were used to spatially model stormwater runoff to understand the relationship between recent changes in land cover and watershed runoff characteristics. High spatial resolution imagery acquired in 1994 and 1996 spatially documented pre‐ and post‐development land cover conditions within the watershed. The water quality model Agricultural Nonpoint Source Pollution (AGNPS) evaluated land characteristics such as soil type, topography, and land cover to simulate surface water flow and sediment transport over past and current land cover conditions. Results of the model were used to locate net increases of fresh water discharge and to suggest best management practices (BMP).