Modeling Surface Water Flows in the Congo River for an Integrated Watershed Management

Integrated water resources management (IWRM) in large watersheds is a major challenge due to the high spatial variability of rainfall, the effects of climate and environmental changes that are increasing and especially their transboundary nature accompanied by growing socio-political tensions. This case study focuses on the Congo River basin, which, due to its vastness, offers valuable insights into the impact of natural processes on sediment dynamics, coastal features, and the evolution of the estuary downstream from its mouth. This research proposes to model surface runoff based on the curves number method, implemented in Soil and Water Assessment Tool (SWAT) and QGIS (QSWAT) software. Data are collected from international public databases, satellite images and ground observations (hydrometric data for the period 2010–2014). For discretization, a spatial division of 303 sub-basins was made corresponding to average areas of Hydrologic Response Unit (HRU) ranging from 0.89 to 190,280.59 Km². The built model allowed simulation of the monthly flows of the Congo River and its tributaries, with a global coefficient of determination (R2) evaluated at 0.79. It is shown that the most influential parameters on the model performance are: CN2, Sol_AWC, Gw_Delay, and Precipitation.