Rules of river avulsion change downstream.

Avulsing rivers create new pathways on the floodplain and the associated flooding can profoundly affect society. River avulsions are thought to occur when the water column becomes perched above the floodplain or when the slope down the flanks of the channel provides a steeper descent than the existing river channel. We test these classical ideas by quantifying the topography around avulsing rivers and show that these mechanisms, historically invoked separately, work together.

Sediment delivery to sustain the Ganges-Brahmaputra delta under climate change and anthropogenic impacts.

The principal nature-based solution for offsetting relative sea-level rise in the Ganges-Brahmaputra delta is the unabated delivery, dispersal, and deposition of the rivers' ~1 billion-tonne annual sediment load. Recent hydrological transport modeling suggests that strengthening monsoon precipitation in the 21st century could increase this sediment delivery 34-60%; yet other studies demonstrate that sediment could decline 15-80% if planned dams and river diversions are fully implemented. We validate these modeled ranges by developing a comprehensive field-based sediment budget that quantifies the supply of Ganges-Brahmaputra river sediment under varying Holocene climate conditions.

Chaos in a simple model of a delta network.

The flux partitioning in delta networks controls how deltas build land and generate stratigraphy. Here, we study flux-partitioning dynamics in a delta network using a simple numerical model consisting of two orders of bifurcations. Previous work on single bifurcations has shown periodic behavior arising due to the interplay between channel deepening and downstream deposition.

Natural processes in delta restoration: application to the Mississippi Delta.

Restoration of river deltas involves diverting sediment and water from major channels into adjoining drowned areas, where the sediment can build new land and provide a platform for regenerating wetland ecosystems. Except for local engineered structures at the points of diversion, restoration mainly relies on natural delta-building processes. Present understanding of such processes is sufficient to provide a basis for determining the feasibility of restoration projects through quantitative estimates of land-building rates and sustainable wetland area under different scenarios of sediment supply, subsidence, and sea-level rise.

Comment on "Wetland sedimentation from hurricanes Katrina and Rita".

Turner et al. (Reports, 20 October 2006, p. 449) measured sedimentation from Hurricanes Katrina and Rita in coastal Louisiana and inferred that storm deposition overwhelms direct Mississippi River sediment input.