Drones for Dam Surveying: Introduction
Unmanned aerial vehicles or drones are a disruptive technology that has the potential to transform business, agriculture, leisure, medicine, and surveillance. Particularly, drones offer unique opportunities for dam surveying and large-scale structure monitoring. Note that dams play a crucial role in water resources development and management and dam surveying is essential to ensure human and environmental health. From irrigation and hydropower to water supply and flood control, both single and multi-purpose dams are critical to economic growth and global health.
Additionally, dam safety has become a relevant topic over the years. In the US alone, the State Dam Safety Program reported 173 dam failures and 587 incidents between 2005 and 2013 (Ridolfi et al., 2017). Note that the most common causes of dam accidents include:
- Overtopping due to poor design and blockage of spillways
- Foundation instability can be affected by uneven terrain and earthquakes
- Cracking and piping can form sinkholes
- Improper construction, operation, and maintenance
- Vandalism or terrorism can result in failure and flooding
Therefore, vulnerability assessment and monitoring of dams are paramount to prevent catastrophes and ecological crises. With a combination of advanced sensor equipment, flexible communication systems, and compact designs, drones can be successfully implemented in dam surveying and visual evaluation of large-scale structures and hard-to-reach areas. Moreover, robotic vehicles are fast and cost-effective tools, which can facilitate dam 3D modeling and improve health and safety regulations across the globe.
Accuracy Analysis of a Dam 3D Model from Drone Surveys
Unmanned aerial technology can be employed in drone surveying and 3D modeling. Due to varying hydrostatic levels and hard-to-reach areas, surveying dams and other large-scale structures can be a challenging task. However, drones can be used to provide essential information via ground control points and dense point clouds. Note that control points are vital in traversing and geo-referencing to establish network control and evaluate higher-dimensional objects. Dense point clouds, on the other hand, are essential in 3D modeling and topography to provide high flexibility and fidelity data.
To evaluate the benefits of drones for dam surveying, Ridolfi and colleagues (2017) assessed the accuracy of dam models obtained by drone surveys. The research team performed evaluations at Ridracoli dam in Italy, focusing on the availability of its water resources. Note that the Ridracoli dam has the following specifications:
- The Ridracoli dam is a masonry arch-shaped construction.
- The dam has a height of 103.5 meters and crowning length of 32 meters.
- The widths at the foundations are 30 meters, while those at the crowning equal seven meters.
Additionally, Ridolfi and colleagues (2017) performed an analysis on the upstream face of the dam and created a 3D framework for geometry recreation, vulnerability evaluation, as well as static and dynamic analyses. Note that one of the main techniques employed in the study was the Structure from Motion (SfM) technique, which is an innovative technology used in the development of 3D models from 2D images. Findings showed that drone technology could surpass traditional topographic methods and provide accurate data for dam surveying. Drones provide dense point clouds, accounting for vertical elevation, vegetation, and the actual ground underneath the construction.
Drones and Dam Surveying: Applications in Research and Practice
Unmanned aerial technology or drones can be effectively employed in dam surveying and 3D modeling. As explained above, such data can support geometry recreation and static and dynamic analyses in vulnerability studies. Apart from dam surveying, drones can be used to evaluate a wide range of dam projects:
- Drone and Removal of Dams: Removal of dams are beneficial in watershed restoration and damaging and decommissioning. Drones can facilitate the measurement of water flow, suspended material, and water depth, including moraine-dammed lakes. Unmanned aerial technology can be used to create 3D models of overlapping photos and provide data for cross-sectional surveys. Consequently, data can improve health and safety regulations worldwide.
- Drones and Temperature Assessment of Dams: Human activities impact aquatic environments and ecosystems; dams, in particular, often affect the downstream river temperatures. Drones with thermal sensors can be used to assess hydrologic, geomorphic, and riparian characteristics and habitat variation. Interestingly, thermograph assessments via drones can support other aspects of dam construction and maintenance, such as building efficiency and defects detection.
- Drones and Water Levels Measurements: Drones can support hydrological observations to improve the assessment of water variability and flood forecasting. As unmanned aerial vehicles are non-invasive technology, drones can be used not only in dam surveying but in the monitoring of inland lakes and other water basins.
- Drones and Dam Construction: Because unmanned aerial technology can assess hard-to-reach areas, drones can also be used for inspection of construction works. Moreover, drones can detect damages and evaluate material efficiency. To set an example, Hallermann and colleagues (2015) inspected a dam in Germany via high-resolution orthophotos free of distortions. With immense capabilities, drones are also able to promote safety surveillance and enhance global health.
Drones from Large-Scale Structures Surveying
The possibility of accessing hard-to-reach areas and providing visual evaluations make drones an attractive and cost-effective technology. Such technology can be employed not only in dam surveying but in the assessment of other large-scale structures:
- Drones for Aging Structures Assessment: Via flexible data acquisition, advanced technology (e.g., infrared cameras), and light construction, drones can improve the surveillance and preservation of a wide range of large structures. To be more precise, drones can facilitate aspects such as the aging assessment of structures without the need for scaffolding or trained experts. Note that weather conditions, intensive use, or poor engineering also affect the construction industry across the globe. Interestingly, unmanned aerial technology can be employed in the assessment of cultural monuments.
- Drones for Tall Buildings Evaluation: Drones can be used for tall buildings surveying in emergency settings (e.g., after-earthquake) at low costs. The opportunities for high-quality photogrammetric analyses allow the evaluation of large-scale and complex buildings with high elevations. For instance, Achille and colleagues (2015) used drones to survey the Santa Barbara Bell Tower in Mantua after an earthquake occurred in Italy.
- Drones for Bridge and Viaduct Inspection: Unmanned aerial technology can improve bridge and viaduct inspection, which can be a dangerous and costly task. Drones can detect cracks and spalls to improve the structural integrity of any construction. Note that Hallermann and Morgenthal (2014) used drone technology to inspect bridges and viaducts, providing detailed aerial imaging and documentation. In fact, documentation is essential to enhancing safety regulatory practices across the globe.
Drones for Photogrammetric Surveying and Human Health
Unmanned aerial vehicles can be utilized in dam and large-scale building surveying to improve human and environmental health. By ensuring bridge inspection and dam safety, drones can collect paramount data to prevent catastrophes, such as accidents, flooding, and cracking. Drones can also support watershed restoration and aquatic balance, as well as the development of health and safety regulations.
Drones can be employed in epidemiology research for the monitoring of deforestation and other agricultural expansion, a phenomenon that can lead to a zoonotic spread. Fornace and colleagues (2014), for instance, revealed that drones could be used to assess land and deforestation activity in Malaysia, which influenced the zoonotic spread of malarial parasites.
Drones can support dam surveying and even surpass satellite data in the evaluation of soil erosion, landslides, and glacier movement. Additionally, drones can perform a variety of photogrammetric operations to improve human and environmental health. Unmanned aerial technology can be used to detect accidents, gas, and radiation around water basins and mines and prevent hazards from pathogens. Interestingly, drones equipped with high-resolution photogrammetry software can access and predict cancer risk from high levels of pollution and copper levels in agricultural areas (Capolupo et al., 2015).
Drones for Dam Surveying: Conclusion
Unmanned aerial vehicles or drones are a disruptive technology that can reshape agriculture, surveying, medicine, and infrastructure. The use of drones for dam surveying, in particular, is increasing globally. Evidence shows that drones provide accurate and real-time data which can be used for 3D models of dam surveying and vulnerability analyses. As explained above, dam surveying is paramount as dams play a crucial role in water resource development and watershed restoration.
With innovative technologies, such as Structure from Motion, photogrammetric functions, dense point clouds, and infrared cameras, robotic aerial technology has the potential to surpass traditional topographic methods and satellite data across a wide range of settings. Drones and 3D modeling can be employed not only in dam surveying, but the evaluation of large-scale structures, tall buildings, bridges, soil erosion, and glacier movement.
With the advancements in unmanned aerial technology, drones harness dam surveillance, water resources management, as well as safety and health regulations.
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