Development of a hydrological model for vegetated swales under different rainfall and swale properties

Global warming and climate change affect the number and magnitude of flash floods dramatically, which necessitate effective and innovative solutions. Low Impact Development (LID) has gained importance recently in decreasing the negative impacts of floods in urban areas. LID such as swale, bioretention, infiltration trench, and rain garden emerge as an alternative or complementary solution to the traditional infrastructure stormwater drainage systems. Vegetated swales are one of the most common types of LID used for stormwater runoff control. Although existing software programs have recently integrated modules for LID into their modeling and design, they need improvement for accurate simulations of the hydrological behavior of vegetated swales. Therefore, in this study, a mathematical model was developed to simulate vegetated swale hydrology. The model calculates the overland flow over the watershed area, the overflow over the swale surface, and the drainage flow at the bottom of the swale. A large-scale experimental setup called Rainfall-Watershed-Swale (RWS) was employed in developing the mathematical model, and data obtained from the RWS was used to calibrate the model. Results show that the developed hydrological model accurately simulates the hydrological behavior of swales under different rainfall events and swale properties. PRACTITIONER POINTS: A mathematical model was developed to simulate vegetated swale hydrology. Experimental data from the rainfall-watershed-swale system was employed for model development and calibration. The mathematical model effectively calculates the overflow and drainage flow of a vegetated swale. The model provides a practical tool for the design of vegetated swales.