What does the SURFACE module do?

The Surface module is a small plug-in-pull-out APSim module that communications with the APSwim module to simulate changes in surface seal conductance through time (See the APSwim documentation for more information regarding surface seals within the SWIM water balance model).

The Surface module is able to communicate with APSwim upon each internal SWIM time step to update surface conductance during high intensity rainfall events where SWIM time steps are of short duration. Essentially, the SURFACE calculations "overwrite" the internal SWIM calculations of surface seal just prior to SWIM's attempt at solving its equations for the time step.

Things to note when using the SURFACE module.

• APSwim must be parameterised to use the option for a surface conductance function for the top boundary condition.
• There are 2 surface seal models available within SURFACE. The first model replicates the internal surface seal model of SWIM and this option can be used to regression test the operation of the SURFACE module. The second model is based upon the work of Silburn & Connolly ( Journal of Hydrology , 172 (1995) 87-104.)