BY TIMOTHY A. SCHULER
Where has all the sediment gone" Image courtesy of Landscape Metrics and the Dredge Research Collaborative.
From the December 2016 issue of Landscape Architecture Magazine.

Thanks to a severe shortage of sediment, the tidal marshes of the San Francisco Bay are disappearing, taking with them a vital ecosystem and an important defense against sea-level rise. In response, in June 2016, voters approved a parcel tax that will generate $500 million over the next 20 years for wetland restoration. And yet the sediment hasn?t vanished; it?s a prisoner of the state?s highly altered hydrologic system. ?There?s this incredible resource that?s just sitting behind this constellation of dams,? says Landscape Metrics principal Matthew Seibert. This summer, as a part of DredgeFest California, Seibert worked with the Dredge Research Collaborative and workshop participants to visualize this ?hidden sediment reserve.? Based on data published in the journal Water Resources Research in 2009, the team created an interactive map showing where?and when?California?s sediment was diverted, as well as the cost of removing that sediment, which far exceeds the expected $500 million in tax revenue. Seibert is optimistic, however, especially as the economics of climate change become increasingly apparent: ?The Baylands have an amazing capacity for flood mitigation that I don?t feel is quantified economically yet, or valued as it should be.?
For an interactive version of this m...