科研之友
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摘要
Constructed wetlands are being utilized worldwide to effectively reduce excess nutrients in agricultural runoff and wastewater. Despite their frequency, a multi-dimensional, physically based, spatially distributed modelling approach has rarely been applied for flow and solute transport in treatment wetlands. This article presents a two-dimensional hydrodynamic and solute transport modelling of a large-scaled, subtropical, free water surface constructed wetland of about 8 km(2) in the Everglades of Florida, USA. In this study, MIKE 21 was adopted as the basic model framework. Field monitoring of the time series hydrological and chloride data, as well as spatially distributed data such as bathymetry and vegetation distribution, provided the necessary model input and testing data. Simulated water level profiles were in good agreement with the spatio-temporal variations of measured ones. On average, the root-mean-square error of model calibration on annual water level fluctuations was 0.09 m. Manning's roughness coefficients for the dense emergent and submerged aquatic vegetation areas, which were estimated as a function of vegetation type, ranged from 0.67 to 1.0 and 0.12 to 0.15 s/m(1/3), respectively. The solute transport model calibration for four monitoring sites agreed well with the measured annual variations in chloride concentration with an average percent model error of about 15%. The longitudinal dispersivity was estimated to be about 2 m and was more than an order of magnitude higher than the transverse one. This study is expected to play the role of a stepping stone for future modelling efforts on the development and application of more advanced flow and transport models applicable to a variety of constructed wetland systems, as well as to the Everglades stormwater treatment areas in operation or in preparation.
- 出版日期2010-9-15
