Drone-Based Flood Risk Mapping: Workflow, Best Practices & Use Cases
- Anvita Shrivastava
- 2 days ago
- 5 min read
Devastating in their effects on lives and infrastructure, floods are among the top performers in destruction through natural disasters, with billions of dollars of damage each year. Because of this, it is critical to accurately assess and identify flooding risk and vulnerabilities as a means of preparing for disasters, developing urban plans, and managing environmental systems. The majority of the traditional ways (such as satellite imaging or ground surveys) have limitations such as poor resolution, delays in obtaining results, and accessibility to certain locations.
With the introduction of drone technology, or UAVs, the way to map flood risk has greatly changed. Drones allow for precise and timely collection of high-resolution data while enabling real-time analysis of flood risk. This blog will provide information on the typical workflow to create flood risk maps from drone-collected data, best practices, and examples of drone-based flood risk mapping in action.
Workflow for Drone-Based Flood Risk Mapping
Using a systematic workflow to produce a flood risk map that is usable and useful to decision-makers supports the production of a technically accurate flood risk map. The normal workflow for this process has four basic steps.
Step 1: Planning & Site Assessment
Objective Definition: Determine the purpose of the mapping – e.g., flood hazard assessment, infrastructure monitoring, or emergency response planning.
Site Survey:Â Identify the flood-prone areas, accessibility, airspace regulations, and environmental conditions.
Regulatory Compliance:Â Ensure adherence to FAA rules or local UAV regulations, including flight altitude, permissions, and no-fly zones.
Stage 2: Data Collection
Choosing Drones: Select a multi-rotor drone when you need to create highly detailed maps of an area, but if the area is large, select a fixed-wing drone.
Equipment Used on Drones: The following sensors should be mounted on the drones: RGB cameras to obtain visual data as maps, LiDAR to generate a 3D model of the landscape, and multispectral cameras for analyzing the landscape's vegetation and soil.
Flight Path Planning: Flight paths should be set up so that overlapping images are taken (60-80% overlap) and so that photogrammetry and the resolution of the land features being mapped can be satisfactorily executed by adjusting the flight altitude according to the resolution of the feature you are capturing.
Timing of the Flight: When planning a flight, the time of day must be taken into account. When scheduling a flight, avoid poor weather conditions (high winds, heavy rain) that could adversely affect the quality of the data collected.
Stage 3: Data Processing
Photogrammetry: Use software such as Pix4D, Drone Deploy, Agisoft Photoscan, or similar programs to convert the overlapping images into 2D images (orthomosaics) and 3D images (models).
Digital Elevation Models: Use these models to analyze elevation data on the ground and to analyze water flow patterns.
Hydrological Analysis: Combine drone data with HEC-RAS, SWMM, or similar programs to simulate flood levels of water and hydraulic flow through an area.
Step 4: Risk Assessment & Mapping
Flood-Hazard Mapping: Create maps displaying land areas that are at high risk of flood inundation based on various factors, including land topography and hydrology.
Assessing Vulnerability: Use these maps to overlay information about population densities, existing infrastructure, and land-use patterns to assess possible exposure to flooding.
Visualisation: Use ESRI or QGIS products to build user-friendly flood-risk mapping products and digital dashboards for those responsible for flood-risk management.
Step 5: Reporting & Decision Support
Interactive Mapping Tools: Develop widely accessible and user-friendly inundation maps for the use by local emergency management officials and decision-makers.
Forecasting Information: Create scenario-based predictive information to help local emergency management organisations plan, train, and prepare for flooding.
Ongoing Surveillance: Develop and maintain in-field remote-controlled aircraft surveillance programs to monitor urban flood risk over the long term and document infrastructure condition over time.
Best practices for the development of flood-mapping drones.
When developing drones for use in flood mapping, the following are key elements to ensure that the drone operates to its maximum ability efficiently and accurately:
Perform all pre-flight checks: Ensure battery life is full, all sensors are calibrated, and the flight path is optimized before take-off.
Use of high overlap images: Photogrammetry uses images that overlap 70 - 80% for greatest accuracy.
Weather conditions: Avoid flying in severe weather conditions, as the impact of water reflection will interfere with the accuracy of the sensor.
Save all data: Should eliminate the chance of losing raw or processed data due to storage issues.
Combine data from the drone with GIS and hydrological model data to produce the best overall flood mitigating strategy.
Engage with your reference community and stakeholders: Allow end-users and stakeholders to be part of the development process of the drone and produce maps that can be shared with local authorities and residents to assist in being prepared for and responding to a flood event.
Use cases associated with the use of flood-mapping drones.
Flood mapping with drones has many different uses and impacts in a variety of industry sectors, as follows:
Urban Planning and Infrastructure Management - The mapping of urban drainage networks, the identification of flood-prone areas, the planning of flood-resistant infrastructure, and the enhancement of the stormwater management system.
Disaster and Emergency Incident Response - The expedited evaluation of the areas impacted by flooding and guidance of rescue operations. Monitoring of levees, dams, and embankments to ensure they remain structurally sound.
Environmental & Agricultural Applications - To evaluate the condition of riverside areas, wetlands, and coastal areas for erosion and flooding, as well as monitor crop fields for water and soil erosion due to excessive rainfall.
Insurance and Risk Management and Insurance - Use flood risk maps to assess property insurance risks and document/validate claims related to flood damage.
Future Trends in Flood Mapping Using Drones
Incorporation of AI & Machine Learning: By utilising AI and Machine Learning, you will be able to use drone images automatically to identify areas susceptible to floods
Live Monitoring of Floods with Drones: Drones will be able to have wireless Internet of Things (IoT) sensors to enable you to monitor floods as they occur.
Swarmisation of Drones: Use many drones at the same time to create flood maps across large geographical areas
Fusion of Multi-Sensor Data for Risk Assessment: By using Lidar, thermal cameras, and other sensors to create comprehensive assessments of flood hazards.
Mapping Flood Hazards with Drones enables society to take a new approach to disaster preparedness and to protect citizens from flood hazards. The systematic approach used by most fire departments, coupled with the use of advanced sensors and modelling software, enables fire departments to generate detailed and timely information compared to conventional methods. The versatility of drones for numerous applications provides a wealth of information for both urban planners and emergency responders, and advancements are being made all the time to improve the quality of mapping flood hazards using drones.
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