Designing flash flood control measures for urban areas using the Monte Carlo water flow simulation

In this study, we developed a novel approach for designing flash flood control measures in a contact zone between agricultural land and a built-up area using the hydrological component of the SIMWE model implemented in GRASS GIS as r.sim.water module. The inputs for the Monte Carlo simulation of water flow in this module included a high-resolution digital surface model and land cover data derived from airborne laser scanning data and aerial orthophotographs. The preferential flow feature of the module helped to better represent concentrated flows such as streams. The flash flood control measures were represented by a modified digital surface model and the probabilistic permeability parameter. The proposed flash flood control measures reduced water depths in critical zones by over 50% (10–40 cm), thereby lowering the risk of house basement flooding and enabling the sewerage system to manage locally generated water flow. Time series of high-resolution water depth rasters elucidate the dynamics of the phenomena and efficiency of the flood control measures. The proposed approach has the advantage of providing high spatial resolution coupled with the flexibility of GIS to evaluate various scenarios and flash flood control measures thus improving the urban planning process.