Spatial and temporal variations in land use and land cover in the Njoro and Kamweti River catchments, Kenya

Abstract

The Njoro and Kamweti River catchments are productive catchments that have and continue to experience major land-use changes with consequences on land cover and the associated environmental resources. It is, therefore, crucial to understand the type of changes occurring, spatial patterns, and the rates at which these changes are occurring. In this study, we quantified the changes in land use and land cover that occurred between 1988 and 2019 identifying areas of change and the average annual rate of change. Thematic Mappers (TM) and Enhanced Thematic Mappers Plus (ETM +) and Sentinel images were obtained for 1988 and 2019. Ground truthing was carried out to enable us to verify the accuracy of the remotely sensed data using in-situ observations to refine the classification output. The results obtained indicated that both catchments have experienced intense land-use changes but at different levels. Njoro River catchment’s forest cover and shrubland had decreased at a rate of 6.06 Km²/year and 0.92 Km²/year respectively and the most increase was recorded in farmlands (3.11 Km²/year) as the other land use classes also increased. In the Kamweti River catchment, forest cover showed a decrease at a rate of 0.21 Km²/year, and farmlands also a slight decrease of 0.1 Km²/year while the other land cover classes increased in area coverage during the period 1988-2019.  The changes in land use and land cover were attributed to increased demand for food and housing and thus continued degrading the two catchments especially the Njoro River catchment. Results obtained indicated that anthropogenic activities were the major contributing factors to the changes in Land Use Land Cover experienced in both catchments. We recommend continued analysis of the trends and rates of land cover conversions owing to their potential use by development planners.