I have an existing water balance model which requires the addition of a number of new storages. Nine of these will be dewatered using mobile pumps. My client is proposing to use four mobile pumps to service these nine dams. I am thinking of prioritising the four dams with the least freeboard and assigning one pump to each of these at each time step. If they are all full (zero freeboard) I would default to prioritising the dams in order of catchment area (which is fixed). I can easily program which dam has the least freeboard but how do I select the second, third and fourth least freeboard?