Abstract

Dramatic coastal land loss challenges geologists to provide solutions that are sustainable, timely, and publicly acceptable. Our fundamental understanding of the Holocene delta plain leads to re-establishment of delta building as an obvious solution. We also know that reintroducing river waters and sediments at the scale necessary to achieve sufficient land building to offset current losses, let alone prior deterioration of the landscape, results in massive changes in the ecology of the coastal basins. While from the long-term perspective using the river provides a sustainable solution, in the near-term it disrupts fisheries harvests and provides few tangible benefits. The delta plain simply cannot be rebuilt by the Mississippi in our generation. Alternative approaches to land building include the mechanical conveyance on concentrated slurries of sediments from sediment sources outside the estuaries (e.g., the river or offshore) to fill shallow bays and create marsh substrate without introducing massive quantities of freshwater. However, the use of such techniques, while proven in terms of dredging technology, raises many questions regarding material placement, resulting habitat quality, and long-term sustainability. Geologists must understand the implications for the coast and coastal communities and effectively inform policy-makers of the implications of these restoration options.