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CADDIS Volume 2: Sources, Stressors & Responses

energy sources physical habitat hydrology temperature water and sediment quality stormwater runoff wastewater inputs riparian and channel alteration urbanization

Physical habitat in urban streams

Urbanization can alter the geomorphologic and vegetative structural features of stream channels—that is, their physical habitat.

Photo courtesy of USFWS

Studies have reported many physical habitat alterations associated with urbanization, including (but not limited to):

See the Physical Habitat module for more general discussion of physical habitat in streams (i.e., not just urban streams).

Click below for more information on specific topics

channel enlargement button road crossings button bed substrates and biotic condition button
Figure 38. Schematic representation of the run, riffle and pool structure in two natural and two urban streams in southern California (the rectangle with an X in one of the urban streams represents a culvert). Urban streams had longer habitat segments, higher percentages of runs, and reduced habitat complexity.
From Riley SPD et al. 2005. Effects of urbanization on the distribution and abundance of amphibians and invasive species in southern California streams. Conservation Biology 19(6):1894-1907. Reprinted with permission.
Figure 39. Typical grain-size histograms from urban and rural catchments. The frequency of < 2 mm particles more than doubled in urban streams. Rural streams had a secondary sediment size mode at 8-16 mm; this secondary mode was absent in urban channels, suggesting that these substrate sizes were selectively removed from urban streams.
From Pizzuto JE et al. 2000. Comparing gravel-bed rivers in paired urban and rural catchments of southeastern Pennsylvania. Geology 28(1):79-82. Reprinted with permission.

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