Modeling of Distributary Channels Formed by a Large Sediment Diversion in Broken Marshland

A 2-D DELFT3D model was developed to address the morphological response of Barataria Bay, the sediment deposition rate in the receiving basin, and the impact on the existing distributary channels within the broken marsh system due to the proposed Mid-Barataria Sediment Diversion. The model had a mesh size sufficient to accurately represent the development of the distributary channels, localized flooding, erosion, and salinity in the basin. The model predicts that the receiving basin will experience extensive erosion during the first year the diversion is open creating three major distributary pathways which flood much of the basin in freshwater. Most locations experience peak flood stage when the diversion reaches its peak capacity after which flood stage tends to decrease. The area of open water near the diversion opening will experience higher suspended sediment concentrations than those in the diversion due to the erosion of the receiving basin

Modeling of Distributary Channels Formed by a Large Sediment Diversion in Broken Marshland

A 2-D DELFT3D model was developed to address the morphological response of Barataria Bay, the sediment deposition rate in the receiving basin, and the impact on the existing distributary channels within the broken marsh system due to the proposed Mid-Barataria Sediment Diversion. The model had a mesh size sufficient to accurately represent the development of the distributary channels, localized flooding, erosion, and salinity in the basin. The model predicts that the receiving basin will experience extensive erosion during the first year the diversion is open creating three major distributary pathways which flood much of the basin in freshwater. Most locations experience peak flood stage when the diversion reaches its peak capacity after which flood stage tends to decrease. The area of open water near the diversion opening will experience higher suspended sediment concentrations than those in the diversion due to the erosion of the receiving basin

Increasing Alaskan river discharge during the cold season is driven by recent warming

Arctic hydrology is experiencing rapid changes including earlier snow melt, permafrost degradation, increasing active layer depth, and reduced river ice, all of which are expected to lead to changes in stream flow regimes. Recently, long-term (>60 years) climate reanalysis and river discharge observation data have become available. We utilized these data to assess long-term changes in discharge and their hydroclimatic drivers. River discharge during the cold season (October–April) increased by 10% per decade. The most widespread discharge increase occurred in April (15% per decade), the month of ice break-up for the majority of basins. In October, when river ice formation generally begins, average monthly discharge increased by 7% per decade. Long-term air temperature increases in October and April increased the number of days above freezing (+1.1 d per decade) resulting in increased snow ablation (20% per decade) and decreased snow water equivalent (−12% per decade). Compared to the historical period (1960–1989), mean April and October air temperature in the recent period (1990–2019) have greater correlation with monthly discharge from 0.33 to 0.68 and 0.0–0.48, respectively. This indicates that the recent increases in air temperature are directly related to these discharge changes. Ubiquitous increases in cold and shoulder-season discharge demonstrate the scale at which hydrologic and biogeochemical fluxes are being altered in the Arctic