Threats of Land Use Changes on Wetland and Water Areas of Murang’a County, Kenya

Abstract

Globally, wetlands have declined in area by over 50% since 1900, due to changes in land-use patterns, converting them into farmlands, human settlements, urban centers, and infrastructure development. Land-use changes also impact negatively on the water area (streams, rivers, lakes, reservoirs, and sea) of an area. In this study, the threats of land use changes on wetland and water areas in Murang’a County, Kenya, were assessed, in a bid to understand the main causes for the rapid decline in wetland and water areas in the County. Landsat images of 2001 and 2018 were analyzed using a supervised classification technique to produce Land-use maps in ArcGIS and detect associated changes. Between 2001 and 2018, the wetland area in Murang’a County declined by over 48% while the water area declined by over 25%. Bare-soil/built-up area posed the greatest threat to the conservation of wetlands in the County, taking up 161 ha of the wetland area during the period. The growth of woody shrubs posed the greatest threat to the loss of water areas taking up 152 ha of the water area during the period. Mean total threats facing wetlands differed significantly from mean total threats facing water areas in the County (t = 0.682; p<0.001). It is concluded that wetland and water areas are faced with similar human-induced land use threats but at varying magnitudes. It is therefore critical that specific regulatory legal and policy structures be urgently instituted to curtail further wetland and water area losses.