Can drone surveying be used at disaster sites? 5 key points for utilization

Immediately after a disaster, it is important to grasp the damage situation as quickly as possible, gather information that leads to recovery decisions while minimizing the risk of secondary disasters, and do so safely. In that context, drone surveying is attracting attention as a means that can quickly inspect wide areas and help assess locations that are difficult to access on foot. It is particularly strong for organizing from above situations that are hard to understand from the ground alone, such as landslides, river flooding, road slope collapses, areas around structures after earthquakes, and checking inundation damage.

However, drone surveying is not a cure-all at disaster sites. Compared to routine surveying, different judgments are required concerning wind and rain, dust, radio conditions, flight safety, ongoing rescue activities nearby, target accuracy, and connections with recovery processes. In other words, whether drone surveying is truly usable at a disaster site is not determined by whether the aircraft can fly, but by whether the necessary information can be obtained safely, at what accuracy, and at what timing.

This article organizes the reasons and limitations for using drone surveying at disaster sites, and then explains practical utilization points from five perspectives. It is summarized with considerations for on-site decision-making to be useful for both clients and operators.

Table of Contents

• Reasons and limitations for using drone surveying at disaster sites

• Utilization point 1: Quickly gain a wide-area understanding in the initial response

• Utilization point 2: Confirm the damage extent without entering hazardous areas too much

• Utilization point 3: Early capture of terrain data that supports recovery design and soil quantity estimates

• Utilization point 4: Compare over time to track the progression of deformation and recovery progress

• Utilization point 5: Combine with ground surveying to achieve usable accuracy

• Items clients should check at disaster sites

• Operational considerations operators should keep in mind at disaster sites

• Common misconceptions about drone surveying

• Summary

Reasons and limitations for using drone surveying at disaster sites

The biggest reason drone surveying is valued at disaster sites is that it makes it easy to grasp the situation across a wide area in a short time without spending long periods physically on site. Immediately after an event, there are hidden dangers beyond what is visible—loosened ground, further movement of collapsed earth, flooding, falling rocks, fallen trees, and damaged structures. For that reason, having people walk the site from the outset and check everything in detail, while providing a lot of information, places a heavy burden on safety.

In that respect, aerial photography or photogrammetry with drones makes it easy to organize, at once, an overview of the entire site, the extent of damage, the condition of access routes, the positions of sediment and driftwood accumulation, and deformations at the top and toe of slopes. Not only for initial situation assessment, but also with an eye toward subsequent emergency recovery, permanent recovery, and measures to prevent recurrence, there is great value in preserving aerial records early. As time passes, the shape of the site changes due to people entering, heavy equipment operations, and temporary installations. The ability to record the immediate post-disaster state itself becomes an important asset for later stages.

On the other hand, there are clear limitations to drone surveying at disaster sites. For example, stable flight is difficult in strong winds or heavy rain, and poor visibility degrades image quality. In steep or ravine terrain, there may be blind spots for areas you want to see. Photogrammetric analysis quality can become unstable over turbid water surfaces, monotonous ground, dense vegetation, or dusty environments. Also, during disaster response, rescue, inspection, heavy equipment work, and the establishment of warning zones take priority, so surveying is always a lower priority. You must not fly simply because you can; the stance must align with the overall site safety and priorities.

A common misunderstanding is to assume that high-accuracy deliverables will immediately result just by bringing in drone surveying. In practice, required accuracy differs by purpose. For initial damage assessment, prioritizing a quick grasp of overall trends is more important. For estimating recovery volumes or considering emergency design, a certain level of positional and elevation accuracy is required. For final acceptance or design verification–level decisions, ground control and supplemental surveying are also necessary. In short, at disaster sites it is important to separate priorities of speed, coverage, safety, and accuracy according to the purpose.

Utilization point 1: Quickly gain a wide-area understanding in the initial response

What is first required at a disaster site is to quickly understand where something has occurred and how far the damage has spread. In this initial stage, drone surveying’s value is very high. From the ground alone it is difficult to simultaneously organize the whole of a collapse area, the location of a river channel blockage, the flooded area, points where roads are severed, and candidate temporary access routes.

For example, in landslide disasters, being able to view the collapse head at the top of the slope, the flow paths of the collapsed earth, and downstream accumulation areas as surfaces makes it easier to organize emergency response strategies. In river disasters, being able to overview overflow points, scour, bank damage, driftwood accumulation, and candidate temporary cofferdam locations makes it easier to identify priority response areas. In road disasters, it becomes easier to grasp the upstream and downstream extents of collapse, whether vehicle access is possible, likely detour routes, and whether additional deformation exists on slopes, all in a short time.

At this time it is important not to demand overly detailed survey deliverables from the start. What you really need in the initial response is an overall understanding sufficient for decision-making rather than a perfect three-dimensional model. Disaster response involves on-site checks, vigilance decisions, and preparation of emergency measures proceeding simultaneously, so aerial overview images, simple orthophotos, and records that are easy to compare with current conditions are often more useful. As a client, separating the initial request into whether it focuses on wide-area understanding or whether an early quantity estimate is required will make specifications more realistic.

A caution is that the initial response is where safety management is most difficult. If you fly before on-site personnel fully understand the damage, you risk starting operations with hidden hazards. Confirming safety under flight paths and at takeoff/landing sites, coordinating with nearby activities, noting changes in wind direction and speed, and sharing flight-interruption criteria should be handled even more carefully than in normal times. Disaster sites are time-pressured, but rushing is not the same as starting carelessly. A failure in the initial stage can undermine the entire subsequent measurement plan.

Also, in some cases what is visible from above can still be difficult to analyze. For example, at collapse sites covered with trees, ground surface changes may not be sufficiently visible from above. That does not mean using a drone has no value; rather, you may treat it as an overview-only tool or make plans on the assumption of combining it with other methods. Drone surveying accelerates initial understanding, but in practice it is crucial not to misjudge its purpose and limitations.

Utilization point 2: Confirm the damage extent without entering hazardous areas too much

One of the strengths of drone surveying at disaster sites is its ability to inspect places that are difficult for people to approach. On slopes with high risk of secondary disasters, flooded areas, slopes still at risk of collapse, and around damaged bridges or retaining walls, getting close from the ground itself is high risk. Being able to check the situation from above first has great value for securing worker safety.

For instance, after prolonged rain a slope failure may leave cracks and loose stones around the primary collapse. Upper slope deformations that are hard to see from the ground can be partly confirmed from above. Around rivers, entering places where the footing has weakened or scour has occurred can be dangerous, but looking from the air first helps separate areas to approach from those to avoid. After earthquakes, aerial checks can help identify falling-object hazards, surrounding displacement, and accessible routes around facilities.

It is important to note that flying a drone does not make the site completely safe. Because pilots and their assistants also have to enter the site, selecting takeoff/landing zones and securing movement routes are unavoidable. In disaster sites it can be hard to secure flat, wide takeoff and landing areas. In valleys and near slopes where strong winds and turbulence are likely, aircraft behavior can become unstable. If using a drone to increase safety creates new hazards during takeoff, landing, or transport, that defeats the purpose.

Clients often overlook that requests to photograph dangerous areas require more on-site coordination and safety confirmation time. A simple request to aerially capture a damage location is insufficient; it must be clear how close the operation should get, which time slots will not interfere with surrounding operations, and to what extent you want safe confirmation. Operators should avoid prioritizing desired camera angles excessively and must have operational plans that include withdrawal decisions.

Furthermore, when confirming hazardous areas, care is needed in interpreting footage and images. Although aerial views are easy to understand, they often lack a sense of depth or height, making it easy to misjudge the actual size of steps or undercutting. Even if the end of a collapse slope looks stable from above, the ground can be muddy underfoot. In practice, drone images should be treated not as a substitute for on-site inspection but as information to prioritize those inspections. Understanding this positioning reduces mismatched expectations between clients and operators.

Utilization point 3: Early capture of terrain data that supports recovery design and soil quantity estimates

Disaster response requires not only damage confirmation but also quantity estimates for subsequent emergency and permanent recovery. There are many items that rely on terrain—rough estimates of collapsed soil volume, the extent of transported sediment, in-channel deposits, areas requiring slope protection, planning for temporary roads and work yards, and more. Capturing terrain data early by drone surveying greatly affects the efficiency of later stages.

For example, if you want a rough estimate of collapsed soil volume after a landslide, having current terrain data makes it easier to consider the approximate recovery scale. In river disasters, understanding the positional relationship of deposits and scour can clarify where to intervene temporarily. In road disasters, early capture of the collapse extent and surrounding terrain facilitates consideration of temporary protection, removal, and recovery cross-sections.

The practical point here is to preserve the immediate post-disaster conditions as soon as possible. At damaged sites, the site’s shape changes rapidly due to emergency measures and safety work. When earth is removed, drainage measures are taken, temporary installations are set, driftwood is removed, or heavy equipment operates, the original damaged condition quickly changes. If you later try to revise quantities without an initial record, decisions become difficult. Therefore, drone surveying is better understood as fixing the damaged state in a form usable for future decisions, rather than merely surveying for recovery.

However, when the purpose is quantity estimation, thinking carefully about accuracy requirements is important. The quality needed for an initial image record differs from that required for terrain data used in quantity calculations. If overlap rates, flight altitude, the establishment of control points, handling of elevations, and whether ground checks are performed are left vague, the data may later become “unusable.” Clients should specify how the terrain data will be used—whether a rough estimate is sufficient or if it must be at a level suitable for design review. Operators are responsible for explaining what quality is realistic given site conditions.

Also, at disaster sites the ground surface may not be clearly visible. Vegetation, driftwood, water surfaces, debris, and temporary materials can mean that the analysis does not directly represent the true ground surface. Turbid or uniform water surfaces are particularly incompatible with photogrammetry and can easily result in misread elevations or shapes. Rushing soil-quantity estimates and overtrusting analysis results is risky. Users of the deliverables must distinguish whether what they see is truly ground surface or surface obstacles.

For this reason, it is important for clients and operators to first align on the intended use. Whether the goal is a rough emergency recovery estimate, a design starting point, or explanatory materials changes how the data should be produced. Because time is limited at disaster sites, this upfront alignment on purpose strongly influences the quality of results.

Utilization point 4: Compare over time to track the progression of deformation and recovery progress

Surveying at disaster sites often does not end with a single measurement. Especially at locations affected by aftershocks, rainfall, or rising water, it is necessary to continuously check whether damage is expanding, whether emergency measures are functioning, and how recovery work is progressing. Using drone surveying in a time series makes it easier to compare site changes as surfaces.

For example, after emergency protection is applied to a collapsed slope, you may want to check whether a subsequent rainfall caused new failures. Or after temporary river recovery, you may want to see whether re-deposition of sediment is progressing or whether scour around bank toes is expanding. Conducting these checks only from the ground each time makes it hard to see differences because observers’ positions and viewpoints vary. If you record the same area with a drone, changes are easier to compare and easier to share among stakeholders.

This usage is effective not only immediately after a disaster. During the transition from emergency to permanent recovery, continuously monitoring the status of work yards, changes in drainage, maintenance of temporary roads, and progress in slope protection is useful for adjusting schedules. For clients, it becomes useful material for site explanations and stakeholder coordination; for operators, it helps reconsider work order and recheck hazardous areas.

However, to make time-series comparisons effective, you need to standardize how each survey is conducted and what reference points are used. If coverage, altitude, angle, and reference positions vary, visual comparison may be possible but quantifying change becomes difficult. Reproducing identical conditions every time is challenging at disaster sites, but at minimum you should clearly define the target for comparison and align observation axes. For example, decide in advance which parts of the slope (head and toe), the river (center and bank toe), or the road (damaged and intact ends) will be continuously observed so the data will be useful.

Also, having time-series data makes it easier to align stakeholders’ understanding, but care is needed in how changes are explained. It is dangerous to determine causes or safety solely from image comparison. Even if there is an apparent difference, you must carefully discriminate whether it is a meaningful difference or a visual difference due to lighting or vegetation changes. Grasping change and evaluating it are separate tasks; evaluation requires on-site confirmation and cross-checking with other measurements. If decisions are made based only on the impression of images without understanding this, it can lead to incorrect countermeasures.

When continuously using drone surveying at disaster sites, avoid treating record-keeping as the sole objective; instead, be conscious of how the records will feed into subsequent decisions. Planning with the intention of monitoring change increases the data’s value compared to one-off efforts.

Utilization point 5: Combine with ground surveying to achieve usable accuracy

The most important practical point for drone surveying at disaster sites is not to try to complete everything with the drone alone. The drone’s ability to quickly capture wide areas is a major strength, but ultimately what is needed are data usable for on-site decisions, design, and construction. Achieving the required accuracy and reliability requires combining drone work with ground surveying and on-site inspections.

A practical workflow is to use airborne terrain data to grasp the overall damage and then supplement on the ground at important cross-sections, near structures, boundary conditions, and places where elevation control is needed. Drones excel at surface understanding, while ground measurements excel at pinpointing key points. Dividing the roles in this way makes operation at disaster sites more practical.

This idea is also important for clients. If the introduction of drone surveying is merely for the sake of using a new method, expectations for deliverables become ambiguous. Instead, define roles—drone for wide-area understanding, ground for key confirmations, remote checks for hazardous locations, supplemental surveys where accuracy is required—and the request can be organized more clearly. Operators should not casually claim they can do everything with a drone; they should indicate where ground supplementation is necessary depending on site conditions.

A common misconception is to treat drone surveying primarily as a labor-saving method and therefore minimize ground work as much as possible. At disaster sites the opposite is often true: it is important to reduce entries into hazardous areas while concentrating human effort on the truly necessary ground checks. Not everything should be done on the ground, nor should everything be completed from the air; clarifying roles leads to efficiency.

Also, combining with ground methods is effective for stakeholder explanations. Disaster recovery involves many parties—administration, clients, contractors, survey teams, and local stakeholders. Locations that are hard to understand from aerial overviews are easier to grasp when supplemented with ground key-point data and site photos. Conversely, ground photos alone can fail to convey overall spatial relationships that aerial information clarifies. Practically useful materials are those that connect multiple information sources, not just one or the other.

At disaster sites, decisions must be accumulated under limited time and safety constraints. Therefore, the effectiveness of introducing drone surveying depends more on how it is integrated with other surveying and inspections than on standalone performance.

Items clients should check at disaster sites

Clients requesting drone surveying at disaster sites should first clarify why the measurements are needed. The required deliverables change depending on whether the purpose is damage extent assessment, emergency recovery decision-making, rough quantity estimation, record preservation, or stakeholder explanation. If you request work while the purpose is ambiguous, the operator cannot determine whether to capture broad coverage or focus on detail, nor how much accuracy is required.

It is also important to share site priorities. Rescue, emergency response, and safety assurance are top priorities at disaster sites, and surveying must proceed while coordinating within that framework. It is natural to want results as quickly as possible, but deciding in advance which areas to secure first for decision-making enables realistic operations. Separating initial wide-area assessment from subsequent detailed surveys is especially effective for clients.

Furthermore, keep the intended use of results in mind. The required organization differs whether the deliverables are images for explanation, terrain data for analysis, or base materials for continuous comparison. While attention tends to focus on image capture, in practice you must consider how the outputs will be used after capture when drafting the request.

Operational considerations operators should keep in mind at disaster sites

Operators should not plan and schedule with the same mindset as routine surveying. At disaster sites, on-site conditions can change rapidly, many stakeholders are involved, and priorities are fluid. Therefore, a structure that can flexibly switch decisions on flight feasibility, safety confirmation, and deliverable priorities is required.

Most important is not to force operations on site. From a desire to avoid missed captures, approaching dangerous positions or underestimating wind changes increases accident risk. Operators trusted at disaster sites are those who can make conservative safety-based decisions even in difficult situations.

Also important is accountability for deliverables. Be candid about how much can be interpreted from images or models obtained by drone surveying and where supplementary confirmation is necessary. Deliverables that are useful in disaster response are those that explain usability and limitations rather than those that merely look good.

Common misconceptions about drone surveying

When considering drone surveying at disaster sites, a common misconception is that drones can accurately measure everything in places where people cannot go. In reality, there are unseen locations, places that are hard to fly over, and areas where analysis is unstable. While the aerial reach is broad, it is not omnipotent under all conditions.

Another common assumption is that if images look good then surveying accuracy is sufficient. In practice, visual clarity and surveying quality are not the same. Images may be adequate for damage explanation but additional checks may be needed for quantity calculations or design considerations. It is important to interpret deliverables according to their intended use.

There is also an expectation that introducing drone surveying will immediately speed up disaster response. While overall understanding can be faster, when you include safety coordination, flight-condition checks, analysis, and supplemental verification, efficiency is not automatically optimized. To achieve benefits, drones must be integrated into the site workflow.

Summary

Drone surveying is a method that can be effectively used at disaster sites. It is especially powerful for initial situation assessment, checking hazardous areas, capturing records for recovery consideration, and tracking changes over time. Its clear advantages in disaster response are the ability to view wide areas in a short time, rapidly preserve the immediate post-disaster state, and gather information while limiting human entry into hazardous locations.

At the same time, constraints such as wind and rain, terrain, nearby operations, safety conditions, and required accuracy mean drones cannot do everything on their own. What is truly useful at disaster sites is an operation that leverages drone strengths while combining ground checks and supplemental surveying to produce results tailored to the purpose. Clients should clarify objectives and intended use, and operators should explain safety and limitations.

In practice, combining aerial wide-area understanding with ground-based high-accuracy positional confirmation further improves the reliability of on-site decisions. For example, an operation that uses drones to determine the damage extent and terrain changes and then uses ground methods to securely fix key positions and recovery reference points is highly practical. In such situations, using a ground positioning method such as LRTK—the iPhone-mounted high-precision GNSS positioning device—makes it easier to confirm coordinates of necessary points and perform supplemental measurements on site. Thinking of drone surveying not as a standalone approach but as an operational combination linking air and ground leads to a surveying system that is usable at disaster sites.