Mixing Patterns of River Deltas Obtained From Remotely Sensed Rouse Number

Abstract

River deltas have complex vertical sediment dynamics within their distributary channel networks. These dynamics suggest that remotely sensed suspended sediment concentration (SSC), which captures surface conditions, is insufficient for investigating delta mixing. Here, we propose a method for mapping the Rouse number using AVIRIS-NG imagery from NASA's airborne spectrometer to investigate vertical mixing patterns. The method is based on the inversion of the equation relating depth-averaged and surface SSC from the Rouse theory. We test this method and its assumptions using a global river data set. We apply this approach to the Wax Lake Delta, Louisiana, USA during high discharge (riverine case) and low discharge (tidal case). Our results indicate that the estimated Rouse number effectively reveals patterns of vertical mixing in both cases. Furthermore, we reproduce 3D SSC fields at the distributary channel outlets using the Rouse number and surface SSC maps. Understanding these mixing patterns is crucial for river delta restoration efforts. Our findings suggest that these new remote sensing data offer significant insights into delta dynamics.