National Water-Quality Assessment (NAWQA) Program

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Effects of Urbanization on Stream Ecosystems

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Habitat Characterization

. Habitat is the part of the physical environment in which a plant or animal lives. Characterization of stream habitat is an important component of many water-quality assessments because they help determine the limiting natural and human factors that affect water chemistry and biological communities. Habitat assessments provide measures of land-use impacts to the stream as well as descriptive measures of the physical environment influencing stream biological communities. In this study, habitat characteristics were collected to compare sites along a gradient of urban intensity from low to high and to determine the relation to other physical, chemical, and biological factors.

What we measured:
. Reach characteristics including channel, bank, and riparian measures.

When we sampled:
. Habitat measures were collected once during low-flow conditions at each site.

Field collection protocols:
. Habitat was characterized using methods described in Fitzpatrick and others, 1998.

. Habitat characteristics at the reach scale were measured at 11 equally spaced transects along the sampling reaches and included measurements of stream slope, bank height and slope, bank vegetation, erosion, bankfull width, wetted channel depth and width, presence/absence and identify geomorphic features (riffles, pools, runs), stream velocity, aspect of flow, bed substrate composition, habitat cover, and canopy closure.

What these measures represent:
. Reach scale variables represent local stream conditions that can be directly related to flow and channel alteration, water chemistry, and biological communities.

. Biological communities have specific habitat requirements to live in streams. Habitat variables, such as substrate types (rocks, sand, silt, etc.), stream velocity, available geomorphic features (pools, riffles, runs), and amount of canopy closure (amount of sunlight) help characterize these specific habitat requirements that can affect the types of algae, invertebrate, and fish communities present at a stream site.

. Data collected can be used to help interpret changes in physical (for example, channel characteristics) and chemical (for example, transport of sediment) factors and biological communities associated with streams having different levels of urban intensity in the basin.

Fitzpatrick, F.A., Waite, I.R., D'Arconte, P.J., Meador, M.R., Maupin, M.A., and Gurtz, M.E., 1998, Revised methods for characterizing stream habitat in the National Water-Quality Assessment Program: U.S. Geological Survey Water-Resources Investigations Report 98-4052, 67 p. []

Photos of collecting habitat measures in Raleigh, North Carolina Study Area

Video clips of collecting habitat measures in Raleigh, North Carolina Study Area

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