Geological Hazard Abatement Districts (GHADs) are charged with managing geological hazards within their district. Blackhawk GHAD and Canyon Lakes GHAD are located in the San Francisco Bay Area. They manage risk related to property damage from geologic hazards such as landslides, which is high given the hilly terrain and wet winters in the area. The GHADs frequently receive reports about these hazards from homeowners and other stakeholders and needed an efficient, easy-to-use tool for managing this information. The GHADs also collect data from monitoring devices to help identify at risk areas, and needed a way to quickly visualize this data.
Farallon developed a high performance web application using Farallon’s flexible and cost effective framework. It uses Open Source GIS technologies including GeoServer, PostGIS, and OpenLayers. Google Maps basemap imagery is utilized, allowing the GHADs’ own data to be overlaid on high quality satellite imagery, street maps, or terrain data.
Geologic hazards are displayed as color coded points representing different types of incidents that are being managed. These points can be clicked to access and update detailed reports. The application also displays the location of monitoring devices such as piezometers and horizontal drains as clickable symbols on the map. Data readings from these devices are stored in a PostgreSQL database, which the application utilizes to generate real-time, interactive graphs that can help to identify warning signs, such as abnormally high sub-surface water levels, which can trigger landslides.
County parcel data and other asset information, such as erosion control devices, are streamed into the application through GeoServer. Users can click anywhere on the map to retrieve information about a parcel in the county, allowing the GHADs to quickly find homeowner contact information for notification purposes.
The application allows the GHADs to more effectively protect homeowners from geologic hazards occurring within their community by providing an intuitive and powerful decision support system with low cost, high speed, and easy scalability.