Abstract
Low Impact Development (LID) practices provide more sustainable solutions than traditional piping and storm ponds in stormwater management. However, architects are not equipped with the knowledge to perform runoff calculations at early design stage. In response to this dilemma, we have developed an open-source stormwater runoff evaluation and management tool, Rainwater+. It is seamlessly integrated into computer-aided design (CAD) software to receive instant estimate on the stormwater runoff volume of architecture and landscape designs. Designers can thereby develop appropriate rainwater management strategies based on local precipitation data, specific standards, site conditions and economic considerations. We employed Rainwater+ to conduct two case studies illustrating the importance of considering stormwater runoff in the early design stage. The first case study showed that integrating rainwater management into design modeling is critical for determining LID practice at any specific site. The second case study demonstrated the need of visualizing runoff flow direction in assisting the placement of LID practices at proper locations when the terrain is of great complexity.
Highlights
Rapid urban expansion and the increased impervious surfaces associated with city development have consistently shown to result in degraded aquatic ecosystems (Carter and Jackson, 2007; Hsieh and Davis, 2005; Lee and Bang, 2000; Miltner et al, 2004)
The curve number used in Rainwater+ and shown in Table 1 is from Urban Hydrology for Small Watersheds TR-55 by the U.S Department of Agriculture (DOA) (Cronshey et al, 1985)
In order to better apply localized stormwater management practices, the proposed site has been divided into six sub-zones (Figure 4a) on which the various rainwater management practices are tested with Rainwater+
Summary
Rapid urban expansion and the increased impervious surfaces associated with city development have consistently shown to result in degraded aquatic ecosystems (Carter and Jackson, 2007; Hsieh and Davis, 2005; Lee and Bang, 2000; Miltner et al, 2004). The resultant urban flooding causes exceptionally severe damage where massive, rapid urbanization is occurring due to poorly engineered infrastructure (Huong and Pathirana, 2011; Liu, 2009; Wang, 2001). To address this urgent concern, it is crucial for architects and landscape designers to have a greater understanding and modeling capability of stormwater runoff to face the increasing risks in the future. LID practices increase sustainability by using porous pavement, bioretention, green roofs, rainwater harvesting and other strategies that manage rainwater as close to its source as possible. These approaches increase groundwater replenishment, rainwater reuse, and on-site water balance, while mitigating downstream flooding (Pyke et al, 2011)
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