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Report, 2006

Low-velocity flows in constructed wetlands : physico-mathematical model and computer codes in Matlab-enviroment

Wörman, Anders; Kjellin, Johan


Constructed wetlands play an essential role in reducing nutrient content and heavy metals in wastewater and run-off water. The treatment efficiency strongly depends on flow pattern and residence times of the water, and therefore further understanding of water flow in constructed is of great importance. Flow modeling is here an efficient tool, and this report describes a 2D model for water flow in constructed wetlands. The model is implemented in Matlab environment and applies for stationary, "low velocity" flow with free surface and small water depth relative to the horizontal extension of the wetland. Simulations compute the elevation of the free water surface and calculate flow velocities. Furthermore, a particle tracking routine gives information of flow paths and residence times of the wetland, where particles can be subjected to both dispersion and exchange with stagnant zones. The main purpose of the model is to provide fast and useful computations for practice in wetland technology, and especially to adapt the mathematical formulation to the specific flow conditions prevailing in wetlands.


treatment wetlands; flow model; numerical methods; constructed wetlands; vegetation; wetlands

Published in

Rapport. Miljö, teknik och lantbruk
Publisher: Institutionen för biometri och teknik, Sveriges lantbruksuniversitet

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