Downstream Hazard

Downstream Hazard is Rezatec's geospatial screening tool for dam owners, operators and state dam safety regulators. It targets "hazard creep": new homes, roads and other development appearing inside a dam's inundation zone between formal review cycles, leaving hazard classifications and Emergency Action Plan (EAP) address lists out of date. Doing this review by hand, dam by dam, can take weeks for a single county.

The workflow combines the regulator's dam inventory and hazard ratings (or National Inventory of Dams records) with inundation zones from hydraulic modelling or terrain-based screening. It identifies buildings, addresses and roads within and near each inundation zone and buffer, assigns addresses by reverse geocoding, counts exposed addresses, detects year-on-year development change and flags dams that may need follow-up review. Rezatec describes the building and development-change detection as high-resolution, satellite-derived analysis, using machine learning on optical satellite imagery from two dates to find new buildings.

Results are delivered in the web-based Rezatec Geospatial Platform: interactive maps, filters by hazard class, EAP status, county and update year, editable road-closure points, and exports as shapefile, Excel, CSV or PNG for local emergency managers. Users can upload refreshed inundation zones and rerun the analysis. The North Carolina Department of Environmental Quality uses it across more than 7,450 dams and about 1,600 inundation zones in 76 counties; in a pilot with a US state dam safety program, manual analysis time fell from weeks to hours. Rezatec presents it as a screening aid that supports, rather than replaces, engineering judgement.