Pollutant Dispersion Modeling in Natural Streams Using the Transmission Line Matrix Method

Safia Meddah,Safia Meddah,Omar Hireche,Abdelkader Saidane,Mohamed Hadjel

doi:10.3390/w7094932

Abstract

Numerical modeling has become an indispensable tool for solving various physical problems. In this context, we present a model of pollutant dispersion in natural streams for the far field case where dispersion is considered longitudinal and one-dimensional in the flow direction. The Transmission Line Matrix (TLM), which has earned a reputation as powerful and efficient numerical method, is used. The presented one-dimensional TLM model requires a minimum input data and provides a significant gain in computing time. To validate our model, the results are compared with observations and experimental data from the river Severn (UK). The results show a good agreement with experimental data. The model can be used to predict the spatiotemporal evolution of a pollutant in natural streams for effective and rapid decision-making in a case of emergency, such as accidental discharges in a stream with a dynamic similar to that of the river Severn (UK).

Highlights

The evolution of a pollutant in both natural and artificial streams may be subject to different phenomena such as dispersion, diffusion, advection, sedimentation, adsorption, desorption, etc.Predicting its development and its spread is important for the environmental protection
The setup of the modeling method is made of the following steps: (1) get the best description of the physical phenomenon; (2) define the characteristic parameters of the profile temporal evolution of the pollutant dispersion; (3) find the experimental parameters of the pollutant dispersion; (4) set the hydraulic conditions corresponding to the phenomenon; (5) develop the TLM (Transmission Line Matrix) method and the TLM model to simulate the phenomenon; (6) optimize the TLM parameters by comparing the obtained TLM results to the experimental data; (7) validate statistically and interpret physically the differences between the TLM results and the experimental data; and (8) deduce the final TLM dispersion model
The proposed one-dimensional TLM model provides a good estimate of pollutant longitudinal dispersion in the far field zone of a river, such as the river Severn (UK)

Summary

Introduction

The evolution of a pollutant in both natural and artificial streams may be subject to different phenomena such as dispersion, diffusion, advection, sedimentation, adsorption, desorption, etc.Predicting its development and its spread is important for the environmental protection. The evolution of a pollutant in both natural and artificial streams may be subject to different phenomena such as dispersion, diffusion, advection, sedimentation, adsorption, desorption, etc. In a case of emergency, such as accidental discharges in a stream, the prediction of the pollutant evolution is crucial in effective and rapid decision-making. Such a help in decision-making must be simple and precise, needs a reduced computational time and a minimum input data. Taking into account most dispersion phenomena found in streams complicates the model by increasing the number of input data which makes simulations more difficult, slow, and inadequate for emergency decision-making, where simplicity and speed are the two critical parameters [6]

Methods

Results

Conclusion