A sensitivity analysis of the influence of watershed and development characteristics on the cumulative impacts of stormwater detention ponds
Stormwater detention ponds are a popular stormwater management practice in
many communities and city ordinances often require the uniform use of detention
ponds on all new developments. Stormwater detention ponds are an effective method
of controlling the peak flow rate immediately downstream from a development, but a
number of detention ponds scattered at random locations throughout a watershed may
not effectively control peak flows throughout the watershed.
A sensitivity analysis was conducted to determine correlations between
watershed and development characteristics and the response of the watershed to the
uniform use of detention ponds on all developments. The cumulative impacts of
detention ponds were analyzed for sensitivity to two watershed characteristics:
watershed shape and watershed slope. Peak flow impacts were also analyzed for
sensitivity to four development characteristics: development size, development
intensity, development stage, and development sequence. The sensitivity analysis
was conducted by modeling the cumulative effects of detention in watersheds with
various combinations of these characteristics.
Synthetic watersheds were used for the sensitivity analysis in order to produce
general results and conclusions that can help evaluate the potential for adverse peak
flow impacts in any watershed, rather than being specific to a particular watershed.
The use of synthetic watersheds also provides a controlled environment that allows
the effects of specific variables to be pinpointed. The synthetic watersheds for this
analysis were developed using network topology. Following the sensitivity analysis
using the synthetic watersheds, a “real-world” test watershed was modeled as a means
of evaluating the applicability of the findings of the sensitivity analysis to an actual
watershed. The Ten Mile Creek watershed in Knox County, Tennessee was used as
the test watershed.
Of the six watershed and development characteristics considered in the
sensitivity analysis, watershed shape, the percent of the watershed that was
developed, and the location of the developed areas within the watershed had the
greatest effect on the cumulative impacts of detention ponds in the watershed. These
three factors determined the pattern of impacts that occurred within a watershed.
Development intensity, development size, and watershed slope contributed to the
magnitude of the impacts which were created, but they were not the overriding factors
that determined the pattern of impacts.
School:The University of Tennessee at Chattanooga
School Location:USA - Tennessee
Source Type:Master's Thesis
Keywords:urban runoff floodplains watershed management watersheds
Date of Publication: