Wildfires are uncontrolled fires that ignite and spread through wildlands or rural areas, consuming vegetation and sometimes extending into developed communities. Accurately measuring wildfires is fundamental for effective management, enabling authorities to allocate resources, ensure public safety, and plan for environmental recovery. Precise data collection helps understand a fire’s progression and its potential impacts.
Quantifying Fire Area
Measuring the total area a wildfire has affected provides an understanding of its scale. This measurement, typically expressed in acres or hectares, is obtained through various mapping techniques. Firefighters and mapping specialists use Global Positioning System (GPS) devices to map the perimeter of a contained fire, creating a digital boundary. This ground-based data offers a precise outline of the burned area.
For larger or inaccessible fires, aerial photography and satellite imagery are used. Aircraft equipped with cameras capture high-resolution images, while satellites provide broader coverage, mapping expansive burn scars. Geographic Information Systems (GIS) software processes this imagery, calculating the total acreage within the defined perimeter. This area is a metric for assessing the magnitude of a wildfire and guiding suppression efforts.
Assessing Fire Dynamics
Understanding the active behavior and intensity of a wildfire helps predict its progression and dangers. Fireline intensity, a measure of the heat released per unit of fire front, quantifies the fire’s energy output. This metric is expressed in kilowatts per meter (kW/m) or British Thermal Units per foot per second (BTU/ft-s). Flame length, the visible height of the flames, indicates fireline intensity, as it is easier to observe.
The rate of spread indicates how quickly a fire moves across the landscape, measured in chains per hour (one chain equals 66 feet) or meters per second. This speed is influenced by fuel type, moisture content, wind, and topography. Spotting is another behavior where embers or burning debris are carried by wind ahead of the main fire, creating new ignition points. Spotting can occur over short distances or extend several kilometers, accelerating fire spread and challenging containment efforts.
Technologies for Data Collection
A range of technologies supports the collection of wildfire data.
Ground-Based Observations
Ground-based observations involve fire personnel using handheld GPS devices for perimeter mapping and visual estimations of flame length and rate of spread. This direct observation provides real-time, on-site information.
Manned Aircraft
Manned aircraft, such as planes and helicopters, are equipped with advanced sensors, including infrared (IR) cameras, for aerial reconnaissance. These infrared capabilities allow operators to detect heat signatures through smoke, identify hot spots, and map fire perimeters, especially during nighttime hours. This aerial perspective enhances situational awareness for fire managers.
Satellite Imagery
Satellite imagery provides broad-scale and repetitive coverage, making it invaluable for monitoring large wildfires and burn scars. Sensors like the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS) detect thermal anomalies, indicating active fires, and map burned areas.
Drones
Drones, or Unmanned Aerial Systems (UAS), are increasingly utilized for their maneuverability and ability to gather detailed, localized data. Equipped with thermal and high-resolution cameras, drones can penetrate smoke to identify hot spots, track fire progression, and provide real-time video feeds to ground crews. They can operate in conditions unsafe for manned aircraft.
Evaluating Post-Fire Impact
After a wildfire, assessing its impact is important for rehabilitation and ecological recovery. Burn severity mapping quantifies the damage to vegetation and soil. This assessment often involves comparing pre-fire and post-fire satellite imagery.
Another aspect of post-fire evaluation is testing for soil hydrophobicity, where soil repels water due to intense heat. This can lead to increased runoff, erosion, and reduced water infiltration, making it difficult for new vegetation to establish. Evaluating damage to infrastructure, such as buildings, roads, and utilities, is also part of post-fire assessment, informing reconstruction and restoration efforts.