Landslides are geophysical events caused by nature or human-made events. There are plenty of definitions and types of landslides (Highland L., 2018) that in a philosophical sense, the landslide is defined by the displacement of particles from a high altitude to a lower one and they receive typification according to their order in a cascading effect and the created soil arrangement deformations. The damages, losses, fatalities, and infrastructures represent a plethora of threats for the development of communities. Landslides occur after heavy rainfall, droughts, telluric movements, and natural and human-made explosions. Landslide are classified according to the flow and movement type (Hungr, et al., 2014). Landslides provoked by earthquakes rely on geological formations. Well-endured overhanging rocky slopes to 1° soft slopes with sediments are the range of altitude flows in line with the soil structure. Moreover, the preeminent material that responds to earthquake in a landslide include rocks, colluvial sand, cemented soils, granular alluvium, granular deltaic deposit, and loess. The most common behaviour of landslides before earthquakes are normally triggered by materials that have not previously faced a hit (Keefer, 1984). Furthermore, a recent study shows the typology of landslide in Ganzhou City, China, referring to (15°- 35°) as gentle steep, (35° − 55°) moderately steep and (60°-70°) steep or rotational landslide in subtropical areas. Visual models of their typical landslides are presented in the paper (Zhan, et al., 2021; Hungr, et al., 2014). Typologies of steeps are mentioned as the city has multiple landslides as a consequence of the construction works. Other typologies are based on the degree of collapsing by identifying the volume and shape of mass movement evaluated. For example, in Latin America, Nicaragua, rockfalls and slides occur abruptly as a single mass or group of rock detachment. They can be cause by steep human-made or natural like in the craters. This type of landslide is triggered by earthquakes, rainfalls and human activities close to urban areas along roads or inside mines (Devoli, et al., 2008). These studies reflect the practices of typifying the landslide visually and by the volume of mass moved but they do not contain information of methodological assessment with UAV and there is a lack of studies in the Caribbean Region related to landslide, especially in the Dominican Republic.
There are more than 40 cases of the landslides reported in the scientific community making Japan, Slovenia, China and Canada the most active ones (Abolmasov, et al., 2017; Gariano & Guzzetti, 2016). Furthermore, assessing a systematic literature research of 513 documents utilising the keywords of Landslide and UAV with Scopus data base, the countries of China and Taiwan seems to be presenting findings regarding the application of UAV for landslide. The strategies and operations of these countries may be different against these type of events in contrast to countries in Latin American Region (Moncada & Yamagishi, 2018; Carrera, et al., 2021). Currently, the development of UAV application still undocumented and in the beginning stages in the region. Each country may address their own typification of landslides, methodologies and mitigations plan against the disaster as the event may have different behaviours and materials that make then unique from different contexts. A recent literature in the Dominican Republic regarding landslide typology were not found as may be possible that the country may not face this kind of event recurrently or landslide have been a cascading effect of another event. Furthermore, the application of UAV for landslide in this context were not reported. Nevertheless, according to the literature search, the most recent fields of investigations are related to landslide and UAV are involved in slope, rainfalls, proximity to rivers, earthquake occurrence, volume of mass moved, velocity of landslide, identification of the failure mechanism in early warning in villages and houses, elevations, and stability of the mass near to houses.
Table 2
Top 12 Journals in Landslide and UAV Scopus Data Base
Journals
|
Number
|
Landslides
|
50
|
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives
|
43
|
Remote Sensing
|
33
|
IOP Conference Series: Earth and Environmental Science
|
21
|
Proceedings of SPIE - The International Society for Optical Engineering
|
18
|
Engineering Geology
|
16
|
Journal of Mountain Science
|
11
|
Geomorphology
|
10
|
Journal of Chinese Soil and Water Conservation
|
9
|
Geosciences (Switzerland)
|
8
|
International Geoscience and Remote Sensing Symposium (IGARSS)
|
7
|
The demands of novel methodologies for data collection are imminent as risks, accuracy and time are critical in investigations regarding landslides. The useful outcomes of the UAV are suitable for: (i) Measuring the cross-sections of the landslide, (ii) Analysing volume and slope, (iii) Recording the magnitude of the event, (iv) instructing the early warning systems with the orthomosaics, Digital Terrain Model (DTM), obliques images, 3D point cloud and mesh for measuring elements and presentation purpose. Some of the outcomes complement and supplement the satellites and Geographic Information System (GIS) workflows offering precise, real-time, and more accurate data than the high-resolution satellites imaging. Despite the UAV in the literature is based on RGB sensors and other sensors such as LiDAR, it represents a significant improvement in DTM extractions by the extend of area that the UAV is capable to cover. Around 300,000 m2 utilising one quadcopter is an example of these approaches (Vanderhorst, et al., 2021). The design and models of UAV influence the data type, quality, and time of acquisition by the initial investment involved. According to (Vanderhorst, et al., 2021) there is a workflow that led the implementation of the UAVs in disaster management but did not provide technical explanations. However, it was updated with the prices for understanding in the first step of UAV applications.
However, in disaster management context time is the most valuable asset that UAV, in any professional model, provide indisputably (Álvares, et al., 2018; Vanderhorst, et al., 2020). There are operations with RGB cameras and LiDAR that have been carried out in the literature to understand the accuracy of the works (Wang, et al., 2021). Another study in applying the UAV methodology for pavement damaged by landslide propose 2D and 3D reconstruction of the road and then, utilise the data obtained for damage typology and risk evaluation (Nappo, et al., 2021) The study identified cracks wider than 1 cm, the 3D models were used to locate anomalies, rapid detection of damages and road distress. In disaster from landslides accuracy depends on the UAV used, internet connection and surface conditions (Mao, Hu, Wang, & Long, 2021) Nevertheless, the methodologies of UAV operations for landslide are contrasted in Fig. 2 in a summarized aspect. The walking distance is substituted with the UAV operations, but certain qualitative data remains in the process.