GIS and Remote Sensing Support in Watershed Conservation and Management: Case Study of the Upper Gucha Watershed – Kenya

Abstract

Geospatial Information Systems (GIS) and Remote Sensing, and their capability to capture, store, manipulate and display data, have found great utility in the analyses of any spatial phenomena with speed and accuracy anywhere on/above/below the earth surface. One such application is watershed conservation and management. This study demonstrates the role of spatial technologies, in the identification, delineation of river channel network within watersheds, generation of slope and flow direction maps from digital elevation models (DEMs), besides the analyses of impacts by human activities on land cover through land use practices within the upper Gucha watershed - a major contributor to the Lake Victoria catchment. With a population growth rate of 2.75% per annum and poverty level of 51% and average population density of 874.7 persons per km 2 , this watershed is characterized with land fragmentation and clearing of primary vegetation within the river valleys and swamps for agricultural space. The methodology involved digital contour map preparation, by geo- referencing and digitizing, DEM generation and watershed delineation. Slope map, Stream network and flow direction maps of the watershed were generated as management tools. Using Satellite imageries of years 1990, 2000 and 2013, change detection was done. The results include change detection map, a DEM, slope map and flow direction map of the watershed for visualization of topographic characteristics of the watershed as tools for informed decision making by managers during conservation and management process. Conclusions appreciate and recognize the importance of spatial technologies in watershed conservation and management and recommend their use in developing watershed conservation and management tools.