The SAC-SMA is a continuous soil moisture accounting model with spatially lumped parameters that simulates runoff within a basin. The model divides the basin into lower and upper zones at different depths, and defines the distribution of moisture, i.e., tension water components (driven by evapotranspiration and diffusion) and free water components (driven by gravitational forces) in each of these two zones via a set of parameters. The model uses precipitation and evapotranspiration time series input, along with parameters on soil moisture states and the basin’s relative permeability to estimate the amount of water that enters, is stored in, and leaves the basin.
This model is implemented in GoldSim to assist with computing watershed runoff using precipitation as the main driver. You can use other GoldSim models to plug into this one such as WGEN to generate the precipitation and the Hamon Evaporation model for the potential ET.
Below is a screen capture of the model.
Below is a schematic representation of the generalized hydrologic model. This was obtained from the conceptual model documentation found here.
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