Hawkesbury Flood Layers

Live NSW Government map services, the 2024 flood study extents and the SES emergency response classification stacked over the Hawkesbury-Nepean floodplain. Click anywhere on the map to read ground height and flood status at that point.

Point check

Click the map to query a point.

In Google Maps, right-click a spot and click the coordinates at the top of the menu to copy them, then paste here. Google Maps links with an @lat,lng part also work.

Ground height comes from the NSW 5 m DEM (m AHD). Windsor gauge comparisons are indicative only: the flood surface slopes along the river, so the water level at your point will differ from the Windsor reading.

Jump to

Base map

Overlays

2024 flood study: modelled extents

Design flood extents from the 2024 Hawkesbury-Nepean River Flood Study, built into this page from the published shapefiles (simplified to about 8 m). Tick an event to draw it; every event is tested at each point query whether drawn or not. Source: Data.NSW, 2024 Hawkesbury-Nepean River Flood Study (flood-extents.zip).

Flood emergency response classification

Hawkesbury Floodplain Risk Management Study and Plan 2025 classification of how each area behaves in a flood (NSW SES, June 2025 update). High and Low Trapped Perimeter areas are merged into the matching Flood Island layer, as in the download. Source: NSW Flood Data Portal, Hawkesbury FRMSP 2025 emergency response classification.

Load other flood files

Other shapefile ZIPs, loose .shp/.dbf/.prj sets or GeoJSON (for example the 2024 study depth, level or hazard downloads) can be loaded here; they stay in the browser and join the point check.

Windsor gauge: major floods

Peaks above 12 m at the Hawkesbury River, Windsor. Source: Infrastructure NSW, Records of flooding in the area (July 2022).

Datem AHDNote

Sources

    Flood study PDFs and map books for the 2024 study are on the NSW Flood Data Portal. Hawkesbury City Council's 2025 Floodplain Risk Management Study and Plan, including emergency response classification shapefiles, is also there and loads through the same file picker.

    How to use

    Check a spot

    1. Click anywhere on the map, or paste coordinates into the box under Point check and press Go. The yellow marker shows the queried point.
    2. Read the ground height (m AHD, from the NSW 5 m DEM), whether the point is in a council Flood Planning Area, the most frequent 2024 study flood event that reaches it, and its SES emergency response class.
    3. The Windsor rows show how far the ground sits above or below past Windsor gauge peaks. They are indicative only; the flood surface slopes along the river.

    Get coordinates from Google Maps

    • Desktop: right-click the spot. The first line of the menu is the latitude and longitude; click it to copy. Paste into the coordinate box.
    • Phone: press and hold to drop a pin, then tap the coordinates shown in the search bar or on the pin card and copy them.
    • A copied Google Maps link (the kind with @-33.6,150.8,17z in it) can be pasted as is.

    Layers

    • Overlays stream live from NSW Government servers. Each one lists its source page; the Flood Planning Area only draws once you zoom to about street level.
    • The 2024 study extents and the emergency response classes are built into the page. Tick an event to draw it; every event is tested at each point query whether drawn or not. Sliders set fill opacity.
    • Reading the extents: the 1 in 100 AEP event has a 1% chance in any year; the PMF is the largest flood thought possible. A point reached by the 1 in 20 event is also inside every rarer event.
    • Emergency response classes: High Flood Island is land that stays dry but is cut off and may run out of supplies; Low Flood Island goes under in a big enough flood; Rising Road Access means the road out climbs and stays open; Overland Escape Route means you can leave over land as water rises. Trapped Perimeter areas are merged into the Flood Island layers.
    • Load other flood files (shapefile ZIP, loose .shp/.dbf/.prj, GeoJSON) with the file picker. They stay in your browser and join the point check.

    Tips

    • Switch to NSW Aerial Imagery and turn on the March 2021 or March 2022 flood imagery to see real water against the modelled extents.
    • Keep flood-data.js next to this HTML file. Without it the built-in layers are missing and the sidebar says so.
    • The page needs internet access for base maps, elevation and the Flood Planning Area. Sandboxed previews (iOS Files, chat app previews) show a blank map; open it in a normal browser.

    Release notes

    v1.3 7 November 2026

    • Fixed the 5 m elevation overlay: the service has no tile cache, so the old tile URLs returned nothing. It now renders through the server's image export with a 0 to 60 m stretch.
    • Added a terrain hillshade overlay from the same DEM (off by default).
    • Overlays now show a warning under their row when the server fails to return tiles, and the point check reports a timeout instead of waiting forever.
    • Fixed the contours overlay: the old NSW_Elevation endpoint serves compressed terrain data, not pictures, and its export call fails. Contours and spot heights now come from the NSW Elevation and Depth Theme service.
    • Elevation and hillshade tiles are only requested once panning stops, to go easier on the slow elevation server.
    • Default view now shows only the Flood Planning Area and the 1 in 100 AEP extent; tick other layers as needed.
    • Renamed the files for hosting: index.html and flood-data.js.

    v1.2 7 November 2026

    • Added this Notes tab.
    • Added a coordinate box under Point check that accepts Google Maps "What's here" text and map links, centres the map and runs the point check.

    v1.1 7 November 2026

    • Built in all 12 design flood extents from the 2024 Hawkesbury-Nepean River Flood Study (1 in 2 AEP through PMF), converted from the published shapefiles and simplified to about 8 m.
    • Built in the Hawkesbury FRMSP 2025 flood emergency response classification (five classes, June 2025 update).
    • Point check now reports the most frequent event reaching the point, the rarer ones it also sits in, and the emergency response class.
    • File picker kept for other files and relabelled.

    v1.0 7 November 2026

    • First build: NSW base maps, Flood Planning Area, 5 m elevation shading, contours, March 2021 and March 2022 flood imagery, cadastre, point check with Windsor gauge comparison, jump chips, gauge table, sources list, shapefile and GeoJSON file picker.

    Data sources and service endpoints are listed under Sources on the Map tab and in flood-map-handover.md.