Green Roof Runoff Attenuation Simulator (2D)

This 2D companion runs the identical substrate water-balance model as the 3D version, drawn as a flat side-by-side roof cross-section instead of an orbitable scene: a green roof (vegetation, growing substrate, drainage/storage layer, waterproof membrane) on the left, a bare impermeable roof on the right, both hit by the same rainfall hyetograph. Choose a triangular, steady-block or front-loaded storm shape, adjust substrate depth and field capacity, and watch the green roof's substrate fill before any water drains, while the bare roof sheds every drop immediately. A live dual hydrograph and a peak-flow-reduction readout — computed straight from the two simulated outflow curves — turn the "green roofs attenuate stormwater" claim into a number that moves as you change the storm or the roof build-up.