Hydrologic Modeling of the Sudd Wetland using Satellite-based Data

Abstract Study region The Sudd Wetland, located in South Sudan within the Nile River Basin. Study focus This study combines limited in-situ data with satellite-based estimates of wetland inundation extents, precipitation, and potential evapotranspiration to develop a hydrologic model of the Sudd Wetland. Holistic water balance assessments were integrated into the model development process to balance data uncertainty with model complexity. An existing model grounded in historical observations served as the foundation for an alternative model that simulates the Sudd flooded area and outflow. Model improvements were formulated and tested incrementally through an iterative procedure, resulting in new insights on the Sudd hydrology and ideas for future model improvements. New hydrological insights for the region The recent satellite-derived hydrologic data suggests that the existing Sudd model over-predicts the areal flood extents and does not accurately capture the storage-attenuation characteristics of the wetland. However, the remotely sensed information is highly uncertainty and somewhat inconsistent in terms of the Sudd water balance, limiting the complexity of an alternative model. Model simulations and analyses suggest that the model structure and performance could be substantially improved if more accurate estimates of the Sudd inflows and wetland inundation extents could be derived. A significant challenge is the need to distinguish between areas that are physically connected to the Sudd water body, but likely not hydrologically connected and contributing to the main water body that regulates the outflows.