Such a strategy serves as a promising prototype for addressing similar geographical modelling issues, where the time-consuming physical model can be potentially replaced by a simplified GIS model.
The multi-criteria GIS model built by binary logistic regression was able to simulate the results from the hydraulic model with good consistency.
We used a binary logistic regression model to integrate the hydraulic concept in a GIS model. The hydraulic–GIS combined model employs the hydraulic concept in a simplified GIS frame, hence avoiding heavy computation in the hydraulic model and arbitrary coefficients in a GIS model. This research combines two common urban flooding approaches, namely hydraulic and GIS models, in a case study of London, Ontario, Canada. Up-to-date monitoring on the distribution of flood hazards in cities is necessary and valuable for urban planning. This wetland was found to have the potential to provide valuable ecosystem services to the area by attenuating peak flow and thus reducing the occurrence of property damaging flooding downstream.Urban flooding is a reoccurring disaster, and its frequency and intensity are likely to increase in the future due to the increasing frequency of storm events. For a scenario with lower flow rates yet a prolonged peak flow rate, the wetland was less effective, with a 20 per cent reduction observed. Attenuation was most effective for rainfall events with sudden spikes in peak flow, where a 42 per cent reduction of peak flow was observed. Peak flow of the Liesbeek River was reduced in scenarios with the Valkenberg Wetland present to accept on a portion of this flow. The study aims to build a baseline dataset for the research site with the data available at present. While the reduction is not sufficient to reduce damaging floods, the findings provide new knowledge and understanding of the attenuation capacity of this wetland and motivation for expanding sustainable urban drainage within the catchment. The model ran historic flow data to determine the attenuation capacity and to measure peak flow reduction. Research is focused on illustrating the attenuation capacity of this wetland. The study measures the attenuation capacity of a small-scale wetland adjacent to an urban river using a 2D PCSWMM hydrodynamic model. The study site is located within the small, urbanized river system of the Liesbeek River in Cape Town, South Africa, which is prone to localized flooding during annual winter rainfall events.
Attenuation of peak stormwater flow using natural wetlands is one of many sustainable urban drainage methods used to reduce flooding and is an approach of interest for this research. The approach to flood protection has recently shifted from engineered and technical solutions to more sustainable and integrated solutions, by considering social, ecological and physical implications and exploring sustainable urban drainage options. Worldwide urbanization and climate change are influential in changing precipitation patterns and hydrological flow resulting in event driven urban flooding.
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