Lines follow terrain-directed flow paths.
Set rainfall for a selected location and calculate how terrain routes runoff. Colors show each line’s peak flow during the scenario.
Flow is shown in m³/s, and line width represents contributing area. Click a point to inspect its route and elevation profile.
A fixed 384 × 384 grid samples Mapzen terrain tiles at zoom 12, averaging 2 × 2 source pixels. Cell width varies with latitude and is shown on the map. Depressions are filled to a spill elevation (Priority-Flood), then flow is routed to one of eight neighbors (D8). Uniform rain is routed through a conceptual linear-storage model.
The model represents terrain-directed runoff within the selected window. Buildings, culverts, sewers, channel capacity, water depth and inundation boundaries are outside its scope.
Calculation windows that cross the antimeridian are rejected explicitly. Supported center latitudes are 70° south through 70° north.
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