An assessment of the causes and effects of degradation on riparian ecosystems of the eastern semi-arid region of Kenya; A case study of Kaiti river, Makueni County

Abstract

The degradation of riparian ecosystems poses a threat to the livelihoods of communities that depend on these socio-ecological systems (SES) for their well-being. Changes in riparian ecosystems have been evidenced by increasing water shortages and the loss of important and previously common riparian plant species. The riparian ecosystem in Kenya's Eastern Semi-Arid Region is one of the affected zones and information is required to better manage these resources. This case study focussed on the Kaiti River in Makueni County and analysed the socio-economic factors leading to degradation, its effects and physical degradation indicators to inform management strategies to improve the conservation of similar riparian ecosystems in the southeastern region of Kenya. Data was collected using questionnaires, key informant interviews, focus group discussions, transects for key indicator species mapping and photographs. To analyse the data, SPSS version 26.0 interfaced with Chi-square tests, regression and correlation analysis were used to draw relationships between socio-economic factors, effects, and degradation in the watershed. Crop farming was found to be a leading cause of degradation (r square=0.849, F(1, 99)=9.4495, p<0.05) showing that farming accounts for 84.9% of the variations in the degradation of the Kaiti River riparian ecosystem. A calculated beta value implied that a unit raise in crop farming will lead to a rise in degradation of the Kaiti River riparian ecosystem by 0.782 (p<0.05). The results of the study also revealed that livestock farming (r square=0.615, β=0.211, p≤0.05), Lack of riparian conservation awareness (r square=0.573, β=-0.757, p<0.05) and Commercial sand harvesting (r square=0.659, β=0.205, p<0.05) significantly contribute to Kaiti River riparian ecosystem degradation. Other causes significantly contributing to degradation (r square=0.520, β=0.212, p≤0.05,) were poor natural resource governance, poverty, poor infrastructure, climate change and land use changes. The main effects due to degradation were effects on crop production (p<0.05) with the most significant effect being reduced availability of water for irrigation(p<0.05). More effects were on livestock keeping (p<0.05) water availability for domestic use (p<0.05) and more significantly on the ecosystem’s biodiversity (p<0.05). The study found vegetation change, disappearance of bird species, and reduced water flow, to be reliable general indicators of riparian degradation (p<0.05). Ten degradation plant indicator species including Ipomoea kituiensis and five high water table indicator species including Phragmites mauritianus were identified. The study concludes that awareness creation and control of human activity in the Kaiti River riparian zone would significantly reduce degradation. A multi-stakeholder approach whereby the community takes centre stage in monitoring and implementing riparian conservation measures is recommended.