IMPACTS OF LAND USE AND LAND COVER CHANGE ON MOIBEN RIVER FLOW PATTERNS

Abstract

Land Use and Land Cover Change (LULCC) is a key driver of hydrological alterations in river basins, with profound implications for sustainable watershed management and environmental planning. This study examined the impacts of LULCC on river flow patterns in the Moiben River Watershed, a critical tributary in Kenya’s Cherangany water tower that supports domestic, agricultural, and urban water needs, particularly for Eldoret City. Using a combination of remote sensing, hydrological modeling, and future scenario analysis, the research provides insights essential for integrated watershed planning and policy development. LULC maps for 1990, 2005, and 2021 were developed using Landsat imagery, and future (2055) scenarios were projected using the CA-Markov model in IDRISI Selva. Hydrological simulations were performed using the Soil and Water Assessment Tool (SWAT), with climate data from global datasets downscaled using MarkSim DSSAT under the RCP6.0 scenario. Model calibration yielded NSE, R2

and PBIAS values of 0.73, 0.62 and -14.30% respectively whereas model validation yielded values of 0.882, 0.916 and 10.34% in the same order; indicating good model performance. Results show a 78.7% expansion in agricultural land over the study period, with corresponding declines in forest, grassland, and wetland areas. River flow simulations under alternative LULC scenarios revealed seasonal variations, where partial reforestation of agricultural land significantly improved low-season baseflows. Projections for 2055 suggest pronounced dry-season flow reductions, especially from January to June, with a peak in August and a sharp decline toward December. A paired-sample t-test confirmed statistically significant differences in monthly flows between the baseline (2010–2018) and projected (2051– 2059) periods (p < 0.000). Key informant interviews highlighted climate change and weak enforcement of land use regulations as critical emerging challenges. The findings underscore the need for scenario-based watershed planning, improved land governance, and adaptive policies that integrate climate and land use dynamics. This research contributes to the broader discourse on sustainable water resource management by providing actionable evidence to inform local and regional planning frameworks. Integrating land cover monitoring with hydrological modeling presents a viable path toward resilient environmental planning, particularly in data-scarce, climate-vulnerable regions like Kenya.