A two‐layer model for studying 2D dissolved pollutant runoff over impermeable surfaces

Abstract

Dissolved pollutants in stormwater are a main contributor to water pollution in urban environments. However, many existing transport models are semi-empirical and only consider one-dimensional flows, which limit their predictive capacity. Combining the shallow water and the advection-diffusion equations, a two-dimensional physically based model is developed for dissolved pollutant transport by adopting the concept of a 'control layer'. A series of laboratory experiments has been conducted to validate the proposed model, taking into account the effects of buildings and intermittent rainfalls. The predictions are found to be in good agreement with experimental observations, which supports the assumption that the depth of the control layer is constant. Based on the validated model, a parametric study is conducted, focusing on the characteristics of the pollutant distribution and transport rate over the depth.The hyetograph, including the intensity, duration and intermittency, of rainfall event has a significant influence on the pollutant transport rates. The depth of the control layer, rainfall intensity, surface roughness and area length are dominant factors that affect the dissolved pollutant transport. Finally, several perspectives of the new pollutant transport model are discussed. This study contributes to an in-depth understanding of the dissolved pollutant transport processes on impermeable surfaces and urban stormwater management.

Assessment of Runoff Control Effect with Improved Stepped Bioretention System (ISBS) under Various Rainwater Conditions

“…After the rainfall on June 1, although there were two rainfall events, the pollutants attached to the roof were not discharged in time, due to the small rainfall amount and its short duration. The above experimental phenomena are like those of Zhang et al and Hou et al; Zhang et al established a transport model of dissolved pollutants based on two-dimensional physics and analyzed that the intensity and duration of rainfall events have significant effects on the transport rate of pollutants [31], while Huo et al systematically analyzed the relative effects of rainfall characteristics and environmental factors on soil nutrient loss using a structural equation model (SEM). The results showed that maximum rainfall intensity over a 30-min period and rainfall depth had a positive effect on soil nutrient loss [32].…”

Sediment deposition characteristics in shallow saturation excess overland flow for urban Stormwater applications

“…The present study aims to isolate the specific effect of sediment trapping as represented by λ. As such, we neglect other effects not included in Equation (), such as flow infiltration into the bed (Akram et al, 2015), vertical and/or horizontal variability of flow and suspended sediments (Zhang et al, 2021), or effects of bedforms. We also neglect dispersion ($$$ \nu $$$ = 0), and we take h/q to be constant, consistent with the experimental conditions under study.…”