Assessing the influence of climate variability and land cover change on water resources in the Wami river catchment, Tanzania

Understanding the trend, extent, and effect of climate variability and land cover change are globally important for monitoring river catchments water resources. Due to the majority of river catchment from developing countries such as Tanzania experiencing insufficient time series data, the long-term ERA5-Land (1960–2021) reanalysis was used to assess the influence of climate variability and land cover change on water resource in the Wami river catchment. The Mann–Kendal–Sneyer test revealed a change that reflects the effect of land cover change on runoff in 1992, hence the mean annual runoff, precipitation, and actual evapotranspiration decreased by 19%, 9.7%, and 8.9%, respectively, while potential evapotranspiration increased by 5% after the change. Budyko decomposition and climate elasticity methods illustrated that variability change caused a notable contribution to the reduction of Wami River runoff. Hydrological sensitivity analysis revealed that variability of climate is a primary factor that reduced runoff with a contribution of 69%, while land cover change is 31%, this illustrates runoff in the Wami river catchment is more vulnerable to climate variability than land cover change by considering that most of the catchment are classified as arid or semi-arid. Thus, our study emphasizes the importance embracing climate adaptation strategies, particularly a nature-based solution (NbS), to ensure the sustainability of water resources within the Wami river catchment.