A Decision Framework for Stormwater Control in Urbanized Watersheds

Rangarajan, Sri; Henning, Dawn E.; ,

A Decision Framework for Stormwater Control in Urbanized Watersheds

by Sri Rangarajan,
Dawn E. Henning,

Document Type: Proceeding Paper

Part of: World Environmental and Water Resources Congress 2008: Ahupua'A

Abstract:

Historically, urban growth occurred around water bodies due to factors such as easy access to transportation, water supply, and drainage. With the expanded transportation network along with peoples. desires to live in more pristine environments, dense growth from the cities began to spread to surrounding previously undeveloped areas. Significant sprawl continues to occur throughout the nation based on short-term goals rather than a regional, holistic approach. Changes in impervious covers due to the developments are inevitable, however, the effects of these changes are challenging from policy, regulatory and technical perspectives. In this paper, a multi-objective decision framework has been developed to guide the determination of an effective imperviousness that can best achieve the various challenges pertinent to a site where a newer or re-development is being planned. The simulation optimization approach developed here will determine the minimum reduction in impervious cover necessary, under the given site-constraints, so that the developers can strive to meet or possibly exceed this target reduction. Constraints are placed on a site depending on its vicinity to a number of regional challenges that have been grouped into three major categories: (a)hydrologic considerations including variability in rainfall and pre- and post-development flow volumes/peak runoff rates, and groundwater recharge; (b) sustainability (green) considerations including on-site retention/detention and water reuse in terms of its reliability and effectiveness in reducing stormwater volumes/peak flows; and (c) water quality considerations including pollutant load reductions to the receiving water bodies. Metrics for evaluating the various considerations are expressed both quantitatively (e.g., cost factors) and qualitatively (e.g.,weighting factors for the objective functions).

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