Application of GIS-Based Spatially Distributed Hydrologic Model in Integrated Watershed Management:A Case Study of Nzoia Basin, Kenya

Abstract

The overall objective of this study was to study the impact of change of land use / land cover on catchment runoff response using FEWS-Flood Model as the rainfall-runoff conversion model  in Nzoia basin, Kenya. Land use / land cover grid data were processed for the years 1986 and 2000 in IDRISI Kilimanjaro environment while both soil data and necessary meteorological data inputs were processed in necessary formats in ArcView.     The study revealed that loss of forest cover between the year 1986 and 2000 equaled gain in acreage under cropland land/ woodland mosaic in the same period. Analysis of impact of change of land use/ land cover between 1986 and 2000 also revealed increased peaks in resulting hydrographs as a result of increased acreage under crops and reduced forest cover for same storm characteristics. This has given a rationale to recent increased flood disaster in the basin.

Key Words: Nzoia, Integrated watershed management, USGS SFM, land use, land cover