1,744,262
buildings with flood exposure (81.9%)
Pluvial only1,420,687
Compound279,290
Riverine only44,285
Mean depth (flooded)8.0 ft *
Pluvial mean depth0.97 ft
Mean damage index0.206
QPE mean / max17.1 in / 33.3 in
* combined mean inflated by uncalibrated riverine
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Stage IV QPE — Aug 25–Sep 1 2017
Mean total: 17.1 in
Max total: 33.3 in (NW Harris Co.)
Peak 1-hr intensity: 3.1 in/hr
Peak 6-hr: 11.0 in
Source: NCEP Stage IV · Iowa State Mesonet
Max total: 33.3 in (NW Harris Co.)
Peak 1-hr intensity: 3.1 in/hr
Peak 6-hr: 11.0 in
Source: NCEP Stage IV · Iowa State Mesonet
Phase 0 calibration status
Pluvial: CN=88, drainage cap=50mm. Flood extent overestimated — calibrate against FEMA 3m depth grid.
Riverine: Manning's NHDPlus VAA. Stage 10–25m unrealistic for flat Houston — Phase 1 (Helene) will recalibrate.
HAND: pysheds from 3DEP 30m DEM. Channel threshold 1km².
Pluvial: CN=88, drainage cap=50mm. Flood extent overestimated — calibrate against FEMA 3m depth grid.
Riverine: Manning's NHDPlus VAA. Stage 10–25m unrealistic for flat Houston — Phase 1 (Helene) will recalibrate.
HAND: pysheds from 3DEP 30m DEM. Channel threshold 1km².