A mechanistic energy balance model for predicting water temperature in surface flow wetlands

作者：Smesrud Jason K^*; Boyd Matthew S; Cuenca Richard H; Eisner Stephanie L

来源：Ecological Engineering, 2014, 67: 11-24.

DOI：10.1016/j.ecoleng.2014.03.006

• Wetlands
• Temperature
• Energy balance
• Evapotranspiration
• Radiation

Several models have been developed to evaluate the dynamics of water temperature in open water bodies. However, few models have been successful in predicting the water temperatures of wetlands that have significant vegetation coverage. A mechanistic model is presented that estimates the water temperature within surface flow wetlands given basic information on influent flows and water temperature, wetland bathymetry, floating and emergent vegetation plant coverage, and meteorological data. The Heat Source Wetlands (HSW) model presented here was calibrated using data collected from two pilot constructed wetland cells in Salem, OR, USA and a wastewater oxidation pond in Stockton, CA, USA. Overall, the model performed well in predicting the effluent temperatures at these locations with annual root mean squared error values of 0.87-1.69 degrees C tested over a range in temperature gradients (influent minus effluent temperature) of 12.0 to 6.0 degrees C, a range of hydraulic retention times for wetlands (3.2-53 days) and ponds (7.4-27 days), and a wide range of emergent vegetation zone coverage (0-71 percent) under two different climate regimes. Additionally, the model was able to simulate the timing and amplitude of diurnal temperature variations in the CW over two annual cycles by accounting for the advection and dispersion and thermal heat storage within the wetland system, evaluating water and plant canopy energy balances separately, and by simulating the individual energy exchange processes on an hourly or shorter time period. Calibration of the models required local adjustments to the evaporation wind function coefficients to capture latent heat losses and adjustments to simulated water depth within the wetland models to capture the diurnal variations in water temperature. Water temperature dynamics in surface flow wetland systems are of increasing interest in settings where discharges are returned to regulated surface water bodies and the model presented here provides a comprehensive framework within which to evaluate these processes. The model also provides a powerful tool for design of engineered wetland systems when water temperatures are a key aspect of the required wetland system performance.

• 出版日期2014-6