Figure 1. Diagram of a forested watershed. The red line shows the area included, in which all water that falls drains to the lowest point. Water that falls on the outside of the red boundary of the watershed becomes part of the flow of other watersheds not shown. This diagram isof an ideal, non-urban watershed with no engineered movement of water in or out through pipes.
Why important: Watersheds are a crucial feature of natural landscapes. They are no less important to cities and suburbs, even if they include much built structure. Watersheds rarely correspond to political boundaries. Hence watershed management is a political and social process that must cross municipal boundaries, and involve the interest and understanding of many human communities. Watersheds are a kind of ecosystem, because not only do they include the streams and groundwaters that influence the streams, but they also include the surface and subsurface flow toward the streams, the pipes that channel flow in neighborhoods and commercial developments, and the biological and social elements that occupy these lands. The watershed as a concept is spatially extensive, three dimensional, and incorporates social, biological, and physical components.
- Belt, K. 2000. The Baltimore Ecosystem Study water quality and urban hydrology initiatives - stream studies along an urban rural gradient in the Gwynns Falls and Baisman Run watersheds. Maryland Water Monitoring Council Programatic Coordination Newsletter.
- Black, P.E. 1991. Watershed hydrology. Prentice Hall, Englewood Cliffs.
- Brush, G.S. 2009. Historical land use, nitrogen, and coastal eutrophication: a paleoecological perspective. Estuaries and Coasts 32:18-28.
- Pickett, S.T.A., K.T. Belt, M.F. Galvin, P.M. Groffman, J.M. Grove, D.C. Outen, R.V. Pouyat, W.P. Stack, and M.L. Cadenasso. 2007. Watersheds in Baltimore, Maryland: understanding and application of integrated ecological and social processes. Journal of Contemporary Water Research and Education 136:44-55.