Characterizing the Role of Lake Storage Dynamics in the Congo River Basin

Abstract:

Although the Congo River is the world’s second largest, behind the Amazon, in terms of annual discharge and rain forest extent, our level of hydrologic understanding is somewhat limited largely due to a lack of in-situ measurements. This point is even more important in the context of how large tropical wetlands impact global hydrologic and carbon cycles. For example, although the Amazon and Congo are both large tropical rivers, their wetlands appear to function differently. The Congo River is also unique in that it is the only major river to cross the equator twice, which results in a year-round rainfall from the movement of the Inter Tropical Convergence Zone (ITCZ). To better understand how the Congo River wetlands function and their role in global carbon cycle, we first characterize the spatial and temporal distribution of water stores and fluxes throughout the basin. Given the limited in-situ measurements, a combination of modeling and remotely sensed measurements are used. Here, we specifically focus on the role of lake storage dynamics in the Congo River discharge. The Hillslope River Routing (HRR) hydrologic model, Tropical Rainfall Measuring Mission (TRMM) precipitation (3B42v7), Moderate Resolution Imaging Spectroradiometer (MODIS) albedo ( MCD43C3), leaf area index (MCD15A2), land surface temperature (MOD11C1 and MYD11C1) and land cover (MCD12C1), water level changes from radar altimetry, and LandSat based extent measurements over major water bodies are used to estimate basin-wide total water storage variations. The HRR model results, which include hourly water dynamics for the Congo and surrounding basins for the period 2002-2012, are also compared to NASA’s Gravity Recovery and Climate Experiment (GRACE) measurements in order to assess the impact of GRACE signal leakage over the Congo Basin.