Cumulative impact analysis of wetlands using hydrologic indices




Nestler, J.M.
Long, K.S.

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U.S. Army Corps of Engineers


In order to make informed decisions concerning cumulative impact analysis of wetlands, the Corps of Engineers Districts and other wetlands professionals need data often not directly available. Cumulative impact assessment of wetlands includes relating historic patterns of flow, derived from the stream's flow record, to changes in the watershed associated with that stream. Harmonic analysis and time-scale analysis were applied to selected stream records to ascertain their potential for describing cumulative impacts. The study area chosen included selected streams in the White River basin, Arkansas/Missouri. The Cache River received particular emphasis because a significant amount of information was readily available concerning it and its surroundings. Daily flow values were retrieved from each of the streams. Using non-linear, harmonic analysis as well as time-scale analysis (a technique adapted from fractal geometry) to reveal the time-dependent patterns in the respective samples, the results were compared decade-by-decade to discern changes in the historic, seasonal patterns. Other steams in the White River basin were analyzed in the same manner and compared with the Cache River, noting historic changes in land use and stream regulation. The study identifies methods with the potential to differentiate historic time frames in which disruptions were likely to have occurred. The methods appear to be translatable to other geographic areas where streamflow is typically seasonal.


45 p.


harmonic analysis, nonlinear regression, streamflow, hydrology, environmental impact, cumulative impact assessment, time-scale analysis