ABSTRACT
As a land development project is initiated, it is important to perform a regional drainage master plan (RDMP) using a systematic approach to layout major floodwater conveyance and storage facilities (MacKenzie 2010). A RDMP is a watershed-based approach that covers the runoff tributary area across economic zones, transportation networks, and jurisdictional boundaries. The major task in an RDMP is to understand the spatial distributions of storm runoff flows and volumes from the tributary catchments into the waterway under planning, and the temporal distribution of storm runoff due to the changes of land use over the development period. Based on the selected levels of flood protection, such as 2- to 100-year events, an RDMP is a regional investigation using computer-based numerical simulation technology to assess the existing and future flood potential, to provide alternative designs for the drainage outfall systems, to develop various flow diversion strategies to reduce flood damage, to reserve land resources for storage and conveyance facilities, to preserve the water environment, and to estimate the initial costs for construction and annual costs for regular maintenance. The legal report of an RDMP documents the predicted flood flows at design points, boundaries along the floodplains, improvements to the waterway, locations of regional stormwater facilities, corridors of construction zones, and cost sharing among all partnerships. The RDMP for an urban development project presents a regional effort to divert, store, and transport flood flows to downstream man-made drainage networks or natural water bodies.
