This model simulates inflow to a reservoir and discharge via 3 different methods: spillway overflow, evaporation, and controlled discharge with an operating target. Spillway flow is calculated using a weir flow equation that is controlled by water depth over the spillway. The controlled discharge is based on simple decision logic to maintain an operating target level. When the reservoir level falls below the target, discharge is shut off and when it rises above the target, the discharge is turned back on. Since the model uses a 1-day time step, some checks are put in place to prevent discharge and spillway flows from overshooting the daily volume amount that is possible. This is done by calculating the volume of water available for the time step (1 day) and limiting the flow rate by that much over the course of the day.
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