The Cumulative Effect of Wetlands on Stream Water Quality and Quantity. A Landscape Approach

A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis-St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived...

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Bibliographic Details
Published in:Biogeochemistry 1990-07, Vol.10 (2), p.105-141
Main Authors: Johnston, Carol A., Detenbeck, Naomi E., Niemi, Gerald J.
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
Engineering and environment geology. Geothermics
Exact sciences and technology
Floods
Forest soils
Fringe
Land use
Pollution, environment geology
Streams
Suspended solids
Water quality
Water samples
Watersheds
Wetlands
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Summary:A method was developed to evaluate the cumulative effect of wetland mosaics in the landscape on stream water quality and quantity in the nine-county region surrounding Minneapolis-St. Paul, Minnesota. A Geographic Information System (GIS) was used to record and measure 33 watershed variables derived from historical aerial photos. These watershed variables were then reduced to eight principal components which explained 86% of the variance. Relationships between stream water quality variables and the three wetland-related principal components were explored through stepwise multiple regression analysis. The proximity of wetlands to the sampling station was related to principal component two, which was associated with decreased annual concentrations of inorganic suspended solids, fecal coliform, nitrates, specific conductivity, flow-weighted NH4, flow-weighted total P, and a decreased proportion of phosphorus in dissolved form (p < 0.05). Wetland extent was related to decreased specific conductivity, chloride, and lead concentrations. The wetland-related principal components were also associated with the seasonal export of organic matter, organic nitrogen, and orthophosphate. Relationships between water quality and wetlands components were different for time-weighted averages as compared to flow-weighted averages. This suggests that wetlands were more effective in removing suspended solids, total phosphorus, and ammonia during high flow periods but were more effective in removing nitrates during low flow periods.
ISSN:0168-2563
1573-515X
DOI:10.1007/BF00002226