Hydrodynamic Modeling of SuDS (BMPs or LIDs) schemes - Case Study
La Marina is an urban area within the Municipality of Elche (South of Alicante, on the Mediterranean Spanish coast), that is rapidly growing. This growth leads to an increase of impervious surfaces, which generate greater run-off volumes with deteriorated water quality.
The original small urban area has a combined sewer system, but separated foul and stormwater systems are compulsory for the new developments. However, there is no natural water course for the stormwater systems to discharge in the area, and the terrain closer to the sea (the dunes to the right on the picture below) has slightly greater elevation that the adjacent land.
This paper presents how the above problems have been dealt with at the design stage for one of the new developments, called Sector MR-10, which accounts for 50% of the total area to be newly urbanized in La Marina.
Sector MR-10 is located next to the dunes, which form a natural barrier to water run-off coming from the mountains (on the West) to the sea (on the East). The drainage system planned for this development aims to replicate the natural hydrologic cycle, using Sustainable Urban Drainage Systems (SuDS), knowned as well as LIDs or BMPs, through the development, and discharching run-off via infiltration in fields closer to the dunes.
The Micro Drainage PC-based drainage design and analysis software suite has been used for both preliminary and detail design and analysis of stormwater infrastructure via simulation modeling. SuDS techniques employed have been choosen to address the three essential issues of quality of surface water runoff, quantity of runoff and amenity (including biodiversity). The main techniques used are bioretention zones, filter drains, and infiltration trenches and basins. Several WinDes modules have been used for graphically modeling the overall system, including the piped system that links the various SuDS techniques employed.
Each one of Micro Drainage modules is equipped with sophisticated interactive spreadsheets, which can be used with or without the graphical interface. Throughout the suite the network and SUDS structures can be visualized in plan, section or 3 dimensional model, allowing taking design decisions easier and quicker. As an example, the picture below shows water levels reached within a series of filter drains linked with pipes at one step of the simulation for the chosen design storm.
With the Source Control module it is possible to optimize storage and infiltration structures as the ones planned for this project. The picture below shows the graphic of the input flow into one of the structures, and how this volume is laminated and infiltrates into the ground.
The use of WinDes enabled an optimum integrated urbanised drainage ‘system’ to be designed for the Sector MR-10 of La Marina, which had specific difficulties due to the need of simulating the hydrodynamic behavior of a complex SUDS scheme.