Simulation of the Effects of Land Cover on Groundwater Dynamics in Yala Catchment Kenya

Abstract

Groundwater depletion is on an increasing trend due to land use changes. Soil water content is important in plant growth, nutrient transport, and oxygen balance, influencing various physiological and biochemical processes necessary for plant development and ecosystem stability. This study aimed to simulate soil water dynamics and assess the effects of land use changes on groundwater in the Middle Yala Catchment. The objectives were to determine effects of land use on moisture retention, infiltration and water availability for sustainable resource management. This was achieved through field experiments and modelling using HYDRUS-1D. Primary data, including soil moisture and groundwater levels, were collected under different environmental conditions such as tree canopy and grassland plantations. Climate data was collected from the weather station in Vihiga County. HYDRUS 1D model was used to simulate the relationship between land use scenarios under varying soil texture. The findings revealed that grassland areas maintained higher and more stable soil moisture levels than eucalyptus plantations, which experienced significant moisture fluctuations and harmed groundwater recharge. Seasonal rainfall patterns affected soil moisture in diverse ways across land uses, with eucalyptus plantations causing significant depletion due to high water uptake and evapotranspiration. The findings suggest that grasslands are more effective at retaining soil moisture, while eucalyptus plantations may contribute to water scarcity due to high water uptake and. The model accurately captured soil moisture trends in grassland but met challenges with eucalyptus interactions. The study emphasizes the importance of selecting vegetation types that enhance groundwater recharge and advocates for regulated eucalyptus expansion and sustainable agricultural practices.