Eleanor Henson (The University of Texas at Austin, United States); Anastasia Piliouras (Pennsylvania State University , United States); Jon Schwenk (Los Alamos National Laboratory, United States); Michael Lamb (California Institute of Technology, United States); Colin Gleason (University of Massachusetts Amherst, United States)

River deltas host hundreds of millions of people and provide important ecosystem services, including buffering the effect of storms. In this project, we address critical knowledge gaps in river delta science: (i) How are fluxes of water, solutes, and solids partitioned along delta networks? (ii) How are the delta network structure (topology) and dynamics (fluxes of water, solutes, and solids) characterized across spatial and temporal scales and where and how are they responding to changes in climate and human modifications? And (iii) What mechanisms of hydrological connectivity characterize channel-wetland exchanges in global river deltas? During this first year of the project, we have focused on the extraction of water masks and delta channel networks from Landsat imagery to increase the density and accuracy of river delta networks in SWORD. We extracted water masks with our tool DeepWaterMap, which employs a Convolutional Neural Network approach. From the water masks, we extracted river delta networks with our tool RivGraph, which we modified to add attributes to the network as required by SWORD. The extracted networks will be included in the next release of SWORD. Additionally, in this first year, we have focused on the development of a model for partitioning and decay of nutrients over river delta networks. We based the development on numerical modeling results at the Wax Lake Delta using hydrodynamic modeling with ANUGA and our Lagrangian transport model dorado, which can transport particles of different buoyancy and provide information on their travel paths and residence time. That information, combined with nutrient spiraling theory, forms the basis of a simplified model for nutrient transport in river deltas.