2007 BES Annual Meeting Presentation and Poster Abstracts
Baltimore Floodplains: Source or Sink or Both?
Abstract: As the "urban stream syndrome" (USS) has emerged as shorthand for the menu of impacts that can affect urban streams, it is important to revisit assumptions underlying conceptual models describing the USS. While stream incision resulting from urbanization is an important symptom in specific cases of USS, these cases may be exceptional. And while entrenched streams are assumed to be decoupled from their floodplains, channel-floodplain connections seem to remain intact, as floodplain sediment accumulation is continuing in some urban floodplains. This historic and contemporary accumulation has important consequences for a variety of important environmental management strategies. If sediments continue to accumulate in floodplains, removal of legacy sediments may be an iterative process, rather than a one-time capital expense. Moreover, modern urban sediments, often contaminated with a suite of redox sensitive elements, may become a source of materials to the ecosystem after deposition atop thick floodplain deposits. Ultimately, understanding urban floodplains, sediment, and the USS is essential to longer term efforts to invert the impermeable. Specifically, as we adopt management goals to return urban areas to less than 10% impervious cover, it becomes increasingly important to understand how streams and their floodplains will evolve once we return urban areas to less than 10% impervious cover.