Speeding up your simulation

In most cases, the best way to speed up your model is to make it simpler. You should look very carefully at your model and ask yourself the following ques­tions, for example:

·         Do you really need a fine discretisation during calibration? A coarser grid may allow you to do many more calibration runs. Then when the model is calibrated, you can refine the grid for the final simulations - but remember to check you calibration first.

·         Do you really need the Richards equation for unsaturated flow? For regional models, the two layer water balance method may be sufficient, which is very fast. The gravity flow method is also, typically 2-5 times faster than the Richards equation method. Again during the calibration it can be a good idea to use one of the simpler methods and the more detailed method for the final simulations. However, switching between methods will likely invalidate your UZ calibration, and require additional calibration adjustments.

·         Is your MIKE Hydro River simulation too detailed? If your MIKE Hydro River cross-sections are too close together, MIKE Hydro River will run with a very short time step. Regional models can often be run with the simple routing methods in MIKE Hydro River, which are very fast.

If your simulation is still too slow, then several sections in the manual might be of help. In particular,

·         Hardware requirements (V1 p. 28) contains information on different hard­ware configurations,

·         Controlling the Time Steps (V1 p. 81) contains information on how the dynamic time step control works,

·         Overland Flow Performance (V1 p. 105) contains information on how to improve the efficiency of the overland flow solution, which can be very time consuming if you have permanently ponded water,

·         Parallelization of MIKE SHE (V1 p. 87) contains information on the using MIKE SHE with multi-core PCs and 64-bit operating systems.