Wetland Hydraulics along the middle reach of the Congo River revealed by repeat-pass multi-temporal interferometric SAR

The Congo River originates from Southeastern part of Democratic Republic of Congo following a 4,375km semi-circular path to Atlantic, with average annual discharge of 40,200 m³/s. It is expected that the wetland hydraulics vary along the middle reach of the Congo River, including the floodplains with distinct boundary from the Kisangani to the intersection between the mainstem and the Lulonga River, and the vast wetlands in the Cuvette Centrale. In this study, we will use repeat-pass multi-temporal interferometric SAR measurement from ALOS PALSAR data to investigate spatial and temporal variations of dh/dt and examine how the dh/dt patterns are related to topographic relief from SRTM DEM. Early results over the wetlands in the Cuvette Centrale show that two distinct dh/dt patterns exist: rapid changes of dh/dt perpendicular to a narrow band of floodplains along the mainstem, and slow and diffuse dh/dt changes over the interfluvial wetlands. It indicates that the hydrodynamics of the interfluvial wetlands cannot be governed by the fluvial process of river-floodplain exchange. Comparison of dh/dt patterns over the Cuvette Centrale and the upper middle reach of the Congo River will enable us to understand how their wetlands and floodplains are filled and drained during high-water and low-water seasons.