Water Always Wins

In the future, if ecologists need to feed sediment to living marshes to keep up with sea-level rise, they will need a delicate way to do that to maintain marsh health. Scientists are hoping to use local tides to distribute it, a process called “strategic placement.” Another SFEI geomorphologist and other researchers looked at two approaches. One would inject sediment into daily flood tides, allowing them to move it onto the marsh. Called water-column seeding, it would be more in sync with how nature does it than pumping in slurry. But it limits the hours in which sediment can be moved and, thus, its delivery rate. The other method, called shallow-water placement, would dump sediment into shallow water or onto a mudflat so waves and tidal currents can deliver sediment to the marsh in their own time. But with this approach, animals living in the mud may be smothered. Now shallow-water placement is being tested by the Army Corps of Engineers. Scientists will monitor potential harm to those mud dwellers and measure how much deployed sediment actually lands on marshes targeted for restoration.