Author(s): Xin Yan Lye; Akihiko Nakayama

Linked Author(s): Xin Yan Lye, Akihiko Nakayama

Keywords: Smoothed particle hydrodynamics; Contaminant transport; Diffusion; Environmental hydraulics

Abstract: Rainfall infiltrates at varying rates across different land covers, with the excess contributing to runoff. The movement of overland flow follows the terrain profiles and often gathers contaminants which were left on the ground during dry periods. It is commonly due to rainfall which triggers the motion of contaminants, yet there is an inadequacy in monitoring overland flow, leaving the range of contaminant spread to receiving land and streams unknown. With the use of computational models, the dynamics of contaminant transport during one rainfall event can be examined and better understood, serving as a basis for long-term changes of contaminant distribution. A numerical model based on Smoothed Particle Hydrodynamics (SPH) is used to simulate the phenomena, to predict the extent of contaminant transport due to rainfall-runoff. In contrast to SPH-Shallow Water Equation (SPH-SWE) model applied for modelling rainfall-runoff processes, a fully three-dimensional Weakly Compressible SPH (WCSPH) is proposed by representing fluid, contaminant and terrain by particles with their respective properties. Rain particles enter from the atmosphere, each carrying a lumped volume to the ground surface. On the ground level, the fluid particles contributing to runoff acquired concentration while traversing across contaminant sources. Responses towards overland flow included infiltration capacity based on the Curve Number and the surface roughness in terms of the roughness height which were assigned to terrain boundary particles. The verified model is applied to an actual terrain in Malaysia, incorporating elevation and land cover profiles. Infiltration, saturation and runoff generation were successfully demonstrated with contaminant transfer from ground sources, allowing an overview of transport, diffusion, accumulation and deposition of common contaminants. The proposed WCSPH model was able to simulate the variation of contaminant concentration both spatially and depth-wise, highlighting areas and points of high contamination.

DOI: https://doi.org/10.3850/978-90-833476-1-5_iahr40wc-p0434-cd

Year: 2023