Sediment
Fish (migrating)
River flow
drag to pan channel
P(pass) vs gap velocity
sediment % / flux vs time
Dam removal is one of the most direct interventions in freshwater restoration: cutting a breach into an aging or obsolete dam releases decades of trapped sediment and reopens the river to migratory fish. This 2D top-down simulator models a river channel with a dam under your control — breach it gradually or all at once, and watch the stored-sediment pool erode downstream following a real release-rate model, while a school of migrating fish attempts to swim upstream through the gap. Their success is governed by a logistic swimming-performance curve against the local gap velocity, exactly the kind of threshold biologists use to size fish passages — and now the erosion rate, critical swim speed and curve steepness are all tunable, so you can compare a soft-sediment/weak-swimmer scenario against a bedrock/strong-swimmer one directly. A live passage-probability graph and a scrolling sediment/flux time series sit alongside the channel view, and the readouts track stored sediment, downstream flux, gap velocity, and the channel connectivity index — the standard score for how "open" a river has become after barrier removal.