Flood mapping is a terrain problem — why 30 m DEMs fail
Flood-risk planning has to answer a concrete question: if the water reaches a given height here, which streets, buildings and assets go under? The honesty of that answer is set almost entirely by the terrain model underneath it.
Why coarse DEMs blur the answer
Water is decided at the scale of kerbs, embankments, culverts and drainage channels — features a metre or two across. A 30 m public DEM with several metres of vertical error averages all of that away, so the inundation footprint it produces is a smooth approximation that can put the wrong streets under water.
Simulate over a metre-accurate DEM
EarthToDate flood simulation runs over BaseDEM at 0.5–1 m vertical accuracy: set any minimum water level at an area of interest and see the resulting footprint rendered over 1 m imagery. The reach is a real terrain computation, not a coarse fill.
The same terrain engine covers coastal storm-surge and sea-level scenarios, riverine and urban flooding, and downstream flows from dam-breach or post-fire debris cascades — one consistent elevation foundation wherever water meets ground.