Discrete time simulators can be used to model or the analytic equations generally used by ecologists. The user defines the model by defining equations that govern the rates of change in populations, individuals or physical features of the environment. These models are then solved by incrementing time in fixed steps using the current time as an input into these equations. Typical uses for this engine are hydrolic models or air flow models.

Some interesting applications of Discrete Time Simulations are:

### California Department of Water Resources This is an interesting model of California's reservoir system.

### SIMULATION OF STAGE AND THE HYDROLOGIC BUDGET OF DEVILS LAKE, SAUK COUNTY, WISCONSIN