Effective Disaster Management

Preparedness & Risk Mapping

• FHI (Flood Hazard Index) — composite layer highlighting likely inundation/prone zones for screening & priority planning.
  Products: FHI built from DEM hydrology.
• HAND (Height Above Nearest Drainage) — terrain normalised by height above channels; strong proxy for flood/wetness susceptibility.
  Products: HAND derived from DEMSA2/SUDEM.
• TWI (Topographic Wetness Index) — terrain-driven wetness potential; flags saturation and ponding areas.
  Products: TWI from DEMSA2/SUDEM.
• Slope / Curvature / Roughness — terrain derivatives for landslide/rockfall/erosion susceptibility.
  Products: SAGA derivatives (from DEMSA2/SUDEM).
• Model-ready DTM & DEMs — high-res terrain for 1D/2D hydraulic meshes and cross-sections; national coverage options.
  Products: DEMSA2 L3,
  DEMSA2 L1 (2 m),
  SUDEM5 (5 m), SRTM 90 m
• Flow Direction & Flow Accumulation — downslope paths and upslope contributing area to trace channels, headwaters and ponding.
  Products: Hydrology suite (DEM derivatives).
• Stream Order Network / Catchments — hierarchical channel network and drainage areas for floodplain & watershed analyses.
  Products: Stream Order Network / Catchment delineations

Early Warning & Anticipatory Action

• HAND/TWI thresholds — pre-define alert bands for low-lying & saturation-prone assets and communities.
  Products: HAND & TWI + DEM bands.
• Proximity to Rivers / Wetlands / Waterbodies / Coast — buffers for warnings, closures and pre-positioning.
  Products: Distance-to water suites
• Critical-facility overlays — hospitals, schools, shelters & lifelines against flood/landslide susceptibility.
  Products: Admin/POI context packs

Response & Evacuation routes 

• Evacuation routing — combine Flow Accumulation channels, HAND bands and Road networks to plan safe egress.
  Products: Roads base layer + HAND / channels / water proximity
• Crossings & low points — locate overtopping/culvert risk via channel intersections and low-lying depressions.
  Products: Stream Order Network + HAND + depression analysis
• Rapid terrain for HEC-RAS — run 2D flood extents for bridges/culverts and crisis scenarios.
  Products: DEMSA2 L3 / SUDEM5 model-ready terrain

Damage Assessment & Recovery

• Inundation & debris footprints — compare predicted flood corridors/flow paths vs post-event observations to map impact.
  Products: HAND/FHI/TWI pre-event  + post-event mapping inputs.
• Asset & parcel overlays — intersect damage footprints with properties and infrastructure for claims & relief prioritisation.
  Products: Admin/cadastre overlays
• Change & recovery tracking — status dashboards using baseline land-cover/veg and protected-area constraints.
  Products: SANLC 2018 Land Cover, SANBI Vegetation Map , SAPAD/PACA.

Logistics & Resilience Planning

• Accessibility & lifeline routing — roads/bridges plus channel crossings and low-lying segments for redundancy planning.
  Products: Roads + Stream Order + HAND
• Hazard-aware siting — select depots/shelters using elevation bands, water proximity, slope limits and protected-area constraints.
  Products: DEM bands + Distance-to water + Slope + SAPAD/PACA.
• Model-ready terrain sources — DEMSA2/SUDEM for local design; SRTM for large-area baselines.
  Products: DEMSA2, SUDEM5, SRTM 9m