Hot Start Files

Hot start files are binary files created by GeoSWMM that save the current state of the study area’s groundwater and conveyance system at the end of a run. The following information is saved to the file:

·       The unsaturated zone moisture content and water table elevation for each subcatchment that has a groundwater zone defined for it.

·       The water depth and concentration of each pollutant at each node of the system.

·       The flow rate and concentration of each pollutant in each link of the system.

The hot start file saved after a run can be used to define the initial conditions for a subsequent run.

Hot start files can be used to avoid the initial numerical instabilities that sometimes occur under Dynamic Wave routing. For this purpose, they are typically generated by imposing a constant set of base flows (for a natural channel network) or a set of dry weather sanitary flows (for a sewer network) over some startup period of time. The resulting hot start file from this run is then used to initialize a subsequent run where the inflows of real interest are imposed.

It is also possible to both use and save a hot start file in a single run, starting off the run with one file and saving the ending results to another. The resulting file can then serve as the initial conditions for a subsequent run if need be. This technique can be used to divide up extremely long continuous simulations into more manageable pieces.