Investigation of Groundwater–Surface water interaction and land use and land cover change in the catchments, A case of Kivu Lake, DRC-Rwanda

Groundwater is linked to climate change, land use, and land cover changes around the world. This research aims to enhance understanding of hydrological dynamics and environmental changes in the region for sustainable water resource management and conservation. It employs the Soil and Water Assessment Tool (SWAT) model and the standard Groundwater Level Index to determine the hydrological components, groundwater level, and fluctuations of the catchments over time. The model has been rerun with Global Climate Model (GCM) derived scenarios for predicting seasonal hydrological components. To assess changes in the land use and land cover around Kivu Lake, CA-Markov and regression analysis were also applied. Different calibration and validation schemes, as well as hydrological component patterns, were implemented. Across all catchments, streamflow ranged from 40.89 m³s⁻¹–170.45 m³s⁻¹, indicating a good fit between observed and simulated data. At Sake's northernmost point, a catchment's maximum average annual evapotranspiration was 1480.89 mm, with the same amount of precipitation, and the groundwater percolation rate ranged from 103.8 to 318.3 mmyr⁻¹. According to the seasonal hydrological component trends, Shared Socioeconomic Pathway (SSP)119 predicted discharge ranging from 3.5% to 13.6% and SSP545 predicted discharge ranging from 1.8% to 10.83% for all catchments. Furthermore, under SSP119 and SSP545, average ET will range from 3.3% to 13.69% and from 4.33% to 15.63%, respectively. The 88.36% of the catchment from South Kivu in Kalehe district has shifted from forest to agriculture. This has the potential to dramatically alter percolation in the region. The findings of this research will assist decision-makers and resource managers in Kivu Lake catchments in making informed decisions regarding water allocation, land management practices, and conservation efforts.