Institute of Ecosystem Studies

2009 BES Annual Meeting Presentation and Poster Abstracts

Urban stream continuums and gutter subsidies: the effects of engineered “urban karst” on organic matter and lotic ecology.
Belt, Ken
Co-Authors: Belt, Kenneth, Kaushal, Sujay, Swan, Christopher, Stack, William, Pouyat, Richard, and Peter Groffman.

Abstract: Urban streams have often been viewed as simple extensions of stormwater networks. They are, rather, very complex catchment-wide hydrologic ecosystems. Of great importance is the degree of connectivity between civil infrastructure and receiving streams, including pathways for the routing of stormflow, augmentation of baseflow by potable water networks, "upland riparian" sources, and riparian interactions with sanitary sewers. Since every hectare of the urban landscape can be underlain by this dense network of pipes and drains this creates a kind of "engineered karst." This gives rise to an exponential three dimensional expansion of the stream network density connecting almost every groundwater and surface drainage feature in the landscape, essentially making every gutter and rooftop a zero order stream. This creates unique fluxes from ultra-urban hotspots, upland organic matter "gutter subsidies" as well as a novel "urban stream continuum." The ecological implications for urban streams are far-reaching in terms of vastly greater CPOM, FPOM & DOC inputs and stream metabolism, which greatly alter the energetics of food webs. We present several years of base and stormflow data for streams and storm drains of the BES LTER & Baltimore City stream networks, which suggest that the altered drainage pathways and strong terrestrial-aquatic linkages of urban catchments may combine in a way such that these are important locations for the management of catchment pollutant loads to minimize impacts on aquatic ecosystems.