Question Which parameters can I change to try and improve the goodness of fit in RESAP? I tried to vary the "ITERATIONS" option, but nothing changed.
Answer The "ITERATIONS" option in RESAP controls the MAXIMUM number of iterations that the program is allowed to make before stopping. Usually, the computation converges before that limit is reached, therefore increasing this number by itself will not result in the program making more iteration steps. To increase the number of iteration steps, it is best to decrease the step size. This is described in more details in the on-line help for the OPTIMIZATION screen.
The goodness of fit reached by the program should not be affected strongly by those choices (as long as convergence is reached). What really governs the goodness of fit is whether or not the data can be represented by the selected soil model. Often, the best approach to decrease the RMS error is to use more layers in the soil model.