Reservoir Yield Simulator: Sequent Peak Storage Analysis

How big does a reservoir actually need to be? Average annual rainfall is almost never the right answer — a reservoir has to survive the worst multi-month drought in the record, not the average year. This simulator generates a synthetic monthly river-inflow record with tunable seasonal cycling and drought severity, applies the sequent-peak (mass-curve) algorithm from classical water-resources engineering to compute the minimum storage capacity that guarantees a chosen demand through the entire record, and then runs a real month-by-month mass-balance simulation of a 3D reservoir tank at a capacity you control — so you can see, directly, what happens when a reservoir is undersized relative to that requirement: the tank runs dry and demand goes unmet, exactly as the algorithm predicted.