Developing a modeling tool to allocate Low Impact Development practices in a cost-optimized method

Nowadays there is a need to overcome the effects caused by rapid urbanization with more innovative methods. Recently, source control approaches, known as Low Impact Development (LID), are being used by urban planners to cope with water-related problems due to their cost-effectiveness and reliability. To do this, allocation of LID techniques in most suitable locations is done by introducing a new modeling tool called LID locator to the WetSpa-Urban software package and tested in the Watermaelbeek catchment situated in the Brussels capital region. In the first step, almost half of the catchment is eliminated from the implementation of LIDs by considering only pixels with high runoff. Also, by considering the sewer network behavior, the total area of high potential pixels for implementing LID is reduced to the range of 37% and 10% of the entire area of the catchment for different scenarios. In the next step, the selected area is further eliminated by use of suitable location algorithm based on size and other installation limitation of each type of LID. Then, the results are used as an input for the newly developed cost-optimization tool. In the end, the best scenario (10-year design storm with the current state of sewer network) is selected based on their performance in surface runoff volume reduction and the total cost. As a result, maximum flow and total volume at the outlet is reduced by 21 and 8% for the most cost-optimized scenario in January and February 2015. In addition to considering sewer network performance, land characteristics and LID installation limits for LID implementation, producing maps indicating the most cost-efficient locations and combinations for LIDs and visualizing them through the GUI make this tool a user-friendly product. This tool was applied to this case study in Brussels however it is applicable for other urban catchments