Title: Stepwise GIS-based groundwater recharge computation under Urbanization impacts for the Kinshasa capital region (D. R. Congo)

Abstract

The Kinshasa region is well-known in the water world for its nearly half-year rainfall and the presence of the gorgeous Congo River and its tributaries. However, these water resources are under significant strain as a result of population growth and urbanization, which simultaneously raises water consumption. This circumstance results in an overuse of existing water resources, including groundwater, particularly when the drinking water utility does not keep pace with population growth. This is why, in this study, the Spatio-temporal variability of urban expansion was used to establish stepwise GIS-based groundwater recharge computations for time series dating from 2000, 2010, and 2020 over an area of approximately 10,000 km2. The GIS environment was utilized to compile spatial data, which resulted in the creation of maps such as Rainfall Distribution, Evapotranspiration Distribution, Digital Elevation Model, Slope, Drainage Density, Soil, LU / LC, Curve Number Grid, and Runoff Map. After evaluating and assembling all of these maps in a GIS context using a water balance formula, we were able to generate stepwise groundwater recharge estimations for the years 2000, 2010, and 2020, showing areas of high, moderate, and poor recharge. The maximum groundwater recharge estimates for 2000, 2010, and 2020 were 310.518mm/yr, 310.142mm/yr, and 315.492mm/yr, respectively, indicating that areas with high runoff potential have low groundwater recharge rates and vice versa. Overall, groundwater recharge is higher in the Southwest, where we find sand soil type, and lower in the rest of Kinshasa Capital Region, where we find paved areas, clay, clay (light), sand clay, and weathered rock.