Influence of Anthropogenic Activities on Nyangongo Wetland Ecosystem in Nyaribari Chache Sub-County, Kisii County, Kenya
Wetlands are among the most productive ecosystems in the world as they perform diverse functions including; flood attenuation, recharge of underground aquifers, climate regulation, erosion control; water provision for human use as well as acting as habitat for wildlife. Nyangongo Wetland in Kisii County in Kenya covering an area of 825 hectares of land is a key life support system to communities in Lake Victoria Basin. The study was informed by the theory of tragedy of commons on free access to environmental resources .The main objective of the study was to assess the effects of human activities on Nyangongo wetland over the last 30 years. The study adopted a mixed-method consisting of Remote Sensing and GIS-based analysis, to determine Land Use and Land Cover dynamics and associated human-induced alterations in the wetland. 251 respondents were randomly selected for interviews in order to gather data on their overall perception of the wetland, which were corroborated by six Key Informant interviews conducted. The respondents observed that the wetland has been adversely affected by the high demand for agricultural products and pollution of water sources leading to limited access to clean water. Based on image analysis, we established that the areal extent of the wetland in the year 1984 was 72.85ha which had since shrunk to 17.37ha by 2017 demonstrating a drastic reduction of 76%. On the other hand, the area under vegetation reduced from 609.07ha (73.8%) to 148.86ha (18%) by 2017, while Farmland area increased from135.65ha (16.4%) to 473.85ha (57.4%). Built-up area which used to be 7.65ha (0.9%) in 1984 expanded to 185.14ha (22.4%) by 2017 due to population pressure. Loss of biodiversity was identified as the most significant negative environmental effect of Nyangongo wetland as it lost more than 460.21ha of vegetation due to agriculture expansion and for settlement. It is recommended that the County and National governments should intervene by declaring the wetland an Environmental Sensitive area and implement interventions to regulate restoration and relocate land uses that are injurious to the wetland and promote appropriate use of the wetland for posterity.