Here, we evaluate the performance of SWOT data during the cal/val and science orbit phase in 3 estuaries and 1 river deltas; we demonstrate a new method to reconstruct the tidal and river signal from sparse SWOT sampling and; we use these data to calibrate and validate numerical models. We discuss the potential and limitations of our approach in the case of gauged and ungauged settings around the world, and how SWOT re-visit frequency and time-series length, and how spatial complexity of the landscape impact the performance of the approach.

Climate change has transformed coastal and deltaic environments in the Arctic with warmer temperatures, loss of sea ice, higher water levels, and larger storm events. As a result, many cultural sites, infrastructure, and residences have already been eroded or are at high risk of erosion and/or flooding in the coming years. In response to the growing demand from local communities, it is essential to understand hydro-morphological change of the large-scale coastal processes driving coastal change. This project examines the dynamics in the delta of the Coppermine River (Nunavut, Canada). The local community has been especially concerned about one of the deltaic islands containing an important cultural site, the historical graveyard. The aim of this study is to calibrate and assess a hydrodynamic model of the Coppermine delta in the Arctic using data from ongoing field studies of the region. The model is implemented using Delft3D’s D-FLOW/MOR module, which can simulate hydrodynamic. A flexible mesh is created with a spatial resolution of up to 4 m near the traditional cemetery and in the delta mouth. To ensure the model's stability, the grid is orthogonalized and smoothed. Hydrodynamic model predictions are of the same order of magnitude as water level and current velocity measurements in the delta. The tide is diurnal with a maximum tidal range of 0.4 m. Current speed is less than 0.5 m/s and flows mainly in a NE direction. A 3-day simulation demonstrated the model's stability. Arctic delta hydrodynamics are a complex system depending on mechanical processes (sea ice, water level, river discharge, fetch, wave conditions), biological (vegetation) and thermal processes (heat transfer, freeze-thaw). This research project will help develop a more general understanding of hydro-morphological processes in Canadian Arctic deltas, essential for the design of better adapted coastal protection.