Interactive engineering model
SCS rainfall-runoff partition
Change rainfall depth and curve number to divide precipitation into abstraction, retention, and direct runoff.
Preparing the 3D model...
A cutaway soil block is the retention reservoir: its depth stands for the potential maximum retention S and a wetting front descends from the surface as infiltration F fills it. A stacked column beside the parcel splits the rainfall depth into initial abstraction, retention, and direct runoff at one shared inch scale, land cover thins from turf toward pavement as the curve number rises, and the footprint follows the drainage area. Readouts use the standard SCS retention and runoff equations with the rainfall-below-initial-abstraction branch handled explicitly.
Focus the 3D view and use the arrow keys to orbit, plus or minus to zoom, and Home to reset the view.
Text explanation and non-WebGL fallback
A cutaway soil block is the retention reservoir: its depth stands for the potential maximum retention S and a wetting front descends from the surface as infiltration F fills it. A stacked column beside the parcel splits the rainfall depth into initial abstraction, retention, and direct runoff at one shared inch scale, land cover thins from turf toward pavement as the curve number rises, and the footprint follows the drainage area. Readouts use the standard SCS retention and runoff equations with the rainfall-below-initial-abstraction branch handled explicitly.
The numeric controls and readouts remain usable if WebGL is unavailable. Drag or swipe the 3D view to orbit and use a wheel or pinch gesture to zoom. With the 3D view focused, use the arrow keys to orbit, plus or minus to zoom, and Home to reset. The complete numeric lesson is also keyboard-accessible in the adjacent controls and readouts. This model is an educational aid and does not replace applicable design standards or professional review.