Abstract
This study presents a comprehensive hydro-meteorological analysis of the Lake Naivasha Basin, a critical freshwater ecosystem in Kenya's Rift Valley, to evaluate the temporal and spatial variability of precipitation, temperature, evaporation, and lake water levels over multiple decades. The analysis integrates primary and secondary datasets obtained from the Kenya Meteorological Department, the Water Resources Authority, and satellite observations. Rigorous data quality control procedures were applied, including interpolation-based gap filling for missing precipitation and temperature records, outlier detection using visual inspection and Z-score statistics, and homogeneity assessment through the Standard Normal Homogeneity Test (SNHT) and Pettit's test. Spatial datasets were standardised to the WGS 84 UTM Zone 36S coordinate reference system to ensure consistency in spatial analyses. Time-series analyses were conducted using monthly and annual aggregations to examine seasonal and interannual hydro-climatic variability. The results reveal pronounced seasonal and long-term fluctuations in rainfall and temperature, indicating the influence of climate variability and ongoing climate change. A strong association was observed between precipitation variability and lake-level dynamics, with hydrological responses further intensified by anthropogenic pressures such as irrigation expansion and land-use change. These findings enhance understanding of the hydro-meteorological processes governing the Lake Naivasha Basin and provide valuable evidence to support sustainable water resources management, climate change adaptation, and informed regional planning.