The Surface Heat Exchange frame provides a drop down list for Surface Heat Exchange Submodels, with options including: Atmospheric linkage, Full Heat Balance, External Equilibrium Temperature, Constant Equilibrium Temperature and Equilibrium temperature (CE-QUAL-W2 method, EFDC_DSI only).
To activate the heat sub-model in EFDC, the temperature constituent must be activated (Active Modules | Sub-Model Computational Options | Details). The ASER.INP file must be used for all of the thermal sub-models to compute the surface and bottom heat exchange processes.
Depending on whether the current model is EFDC_GVC or EFDC_DSI, the EFDC_Explorer form will have different options shown in the Heat/Temperature frame. The following provide an overview of the approaches.
The EFDC_GVC model uses a new thermal bed model to determine the bed/water column heat exchange (Tetra Tech, 2007c). A sediment thermal thickness is assigned for the entire model. This thickness is not related to either the sediment transport model's bed or the water quality sediment bed. This thermal layer is then divided into KBH layers (must be >2). A constant initial bed temperature can be used or alternatively the TEMPB.INP file can be used to assign a spatially variable initial temperature, by layer. Check the Use TEMPB.INP checkbox in the Bed Thermal Options frame for this option.
The EFDC_DSI version of the model has two different approaches for the bed heat sub-models. If the standard EFDC full heat balance (ISTOPT(2)=1) sub-model is used, the water/sediment bed heat exchange model of the pre-GVC version is used. If the user has selected the equilibrium temperature sub-model (ISTOPT(2)=4) then the bottom heat exchange is computed using the heat exchange coefficient and the user can assign spatially varying sediment thicknesses and initial temperatures using the TEMB.INP file.
Various atmospheric parameters can be adjusted using the Settings button in the Heat/Temperature form. An example of the Atmospheric Parameters values box is shown in Figure 1. The parameters shown in Figure 1 change slightly depending on which heat sub-model is being used.
Figure 1 Atmospheric Parameters.