A Beach Vulnerability Framework for the Galapagos Islands: Fusion of WorldView 2 Imagery, 3-D Laser Scanner Data, and Unmanned Aerial Vehicles
01 Jan 2018-Vol. 9, pp 159-176
TL;DR: In this paper, the authors describe a beach vulnerability framework to assess the Galapagos Islands, and the fusion of remote sensing data and measurement methods associated with high spatial resolution remote systems for beach assessments of sensitive and fragile settings.
Abstract: The scale and impacts of changes to beaches due to natural hazards, human use, economic development, tectonic uplift and subsidence, and climate change, especially, sea level rise and storm surges can generate persistent as well as temporary beach forms that are important to tourism, animal behavior, and conservation of diverse and fragile ecosystems. Vegetated and nonvegetated coastal areas are critical transition zones between land, freshwater habitats, lagoons, wetlands, residential communities, and tourist services as well as the marine nearshore and open ocean. Beaches and their associated environments provide essential ecosystem goods and services, including shoreline protection, nutrient cycling, fisheries resources, habitat and food, and regulation of nutrients, water, sand particles, and organisms. Sandy beaches, in particular, are an essential element of coastal geomorphology, and in the Galapagos Islands, they are critical sites for animal and human uses and interactions. As such, the preservation and management of sandy beaches are important and their sustainability crucial for island ecosystem sustainability. In this article, we describe a beach vulnerability framework to assess the Galapagos Islands, and the fusion of remote sensing data and measurement methods associated with high spatial resolution remote systems for beach assessments of sensitive and fragile settings.
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TL;DR: In this paper, a 3D model of a carbonate cliff affected by a rockfall and showing signs of further instability is presented, and a quick surveying protocol based on the integration of quick methodologies employed for the characterization of the cliff is proposed.
Abstract: The research presented in this paper is aimed at testing an innovative surveying protocol based the integration of quick methodologies employed for the characterization of a carbonate cliff affected by a rockfall and showing signs of further instability. During a post-rockfall emergency, one of the most important activities is evaluating if reactivation of the movements is possible, and if it may represent a threat for a series of elements at risk. On 5 January 2019, intense rainfalls triggered the detachment of a significant volume of fractured limestone and dolostone below the main square of a historical village located in southern Italy in the municipality of Messina, giving rise to one of the greatest landslides occurred at one of the most tourist areas of northeastern Sicily. Fallen blocks damaged the two main infrastructures of the area reaching also a bus terminal, which fortunately was vacant at the time of the rockfall. With the aim of proposing a quick surveying protocol during a post-rockfall emergency, terrestrial laser scanner, infrared thermography, and horizontal to vertical spectral ratio surveys were employed for the geostructural characterization of the cliff and for the investigation of the subsoil below the main square. In particular, the survey through terrestrial laser scanner returned an accurate 3D model of the cliff, where some key structures were highlighted; infrared thermography allowed recognizing caves and fractures along the cliff, with specific reference to a hollow area arising from past rockfalls. Such remote data, along with direct rock mass surveys performed by expert climbers allowed ascertaining that the instability of this cliff is driven by wedges formed by the intersection of 2 and 3 discontinuity systems, which are likely related to the main tectonic systems of the area. The horizontal to vertical spectral ratio survey allowed the identification of a peculiar vertical contrast of impedance, which may be related to a mechanical discontinuity located below the main square of the village, well matching with one of the systems responsible of the instability. The integration of these surveys methodologies resulted a useful quick protocol for the achievement of the key information on the stability of a rock cliff in the initial stage of its securing.
29 citations
TL;DR: In this paper , the authors compared the application of a Terrestrial Laser Scanner (TLS) and Unmanned Aerial Vehicle (UAV) in rock slope stability analysis.
6 citations
TL;DR: Instrumentation is a key factor in the theory and practice of land surveying as discussed by the authors, and slow-paced technology adoption is a major setback to professional practice in the field.
Abstract: Instrumentation is a key factor in the theory and practice of land surveying. At various contexts, slow-paced technology adoption is a major setback to professional practice. Within the context of ...
1 citations
Cites background from "A Beach Vulnerability Framework for..."
...TLS enables experts to obtain fast and accurate geospatial details of the Earth’s features, and therefore creates a useful link between geospatial infrastructure and the teeming needs of big data for a myriad of societal applications (Walsh et al., 2018)....
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Dissertation•
01 Jan 2020
01 Jan 2023
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TL;DR: Lidar has been shown to accurately estimate aboveground biomass and leaf area index even in those high-biomass ecosystems where passive optical and active radar sensors typically fail to do so as discussed by the authors.
Abstract: Articles R emote sensing has facilitated extraordinary advances in the modeling, mapping, and understanding of ecosystems. Typical applications of remote sensing involve either images from passive optical systems, such as aerial photography and Landsat Thematic Mapper (Goward and Williams 1997), or to a lesser degree, active radar sensors such as RADARSAT (Waring et al. 1995). These types of sensors have proven to be satisfactory for many ecological applications , such as mapping land cover into broad classes and, in some biomes, estimating aboveground biomass and leaf area index (LAI). Moreover, they enable researchers to analyze the spatial pattern of these images. However, conventional sensors have significant limitations for ecological applications. The sensitivity and accuracy of these devices have repeatedly been shown to fall with increasing aboveground biomass and leaf area index (Waring et al. 1995, Carlson and Ripley 1997, Turner et al. 1999). They are also limited in their ability to represent spatial patterns: They produce only two-dimensional (x and y) images, which cannot fully represent the three-dimensional structure of, for instance, an old-growth forest canopy.Yet ecologists have long understood that the presence of specific organisms, and the overall richness of wildlife communities, can be highly dependent on the three-dimensional spatial pattern of vegetation (MacArthur and MacArthur 1961), especially in systems where biomass accumulation is significant (Hansen and Rotella 2000). Individual bird species, in particular, are often associated with specific three-dimensional features in forests (Carey et al. 1991). In addition, other functional aspects of forests, such as productivity, may be related to forest canopy structure. Laser altimetry, or lidar (light detection and ranging), is an alternative remote sensing technology that promises to both increase the accuracy of biophysical measurements and extend spatial analysis into the third (z) dimension. Lidar sensors directly measure the three-dimensional distribution of plant canopies as well as subcanopy topography, thus providing high-resolution topographic maps and highly accurate estimates of vegetation height, cover, and canopy structure. In addition , lidar has been shown to accurately estimate LAI and aboveground biomass even in those high-biomass ecosystems where passive optical and active radar sensors typically fail to do so. The basic measurement made by a lidar device is the distance between the sensor and a target surface, obtained by determining the elapsed time between the emission of a short-duration laser pulse and the arrival of the reflection of that pulse (the return signal) at the sensor's receiver. Multiplying this …
1,719 citations
TL;DR: In this paper, a multitemporal dataset consisting of seven Landsat 5 Thematic Mapper (TM) images from 1988 to 1996 of the Pearl River Delta, Guangdong Province, China was used to compare seven absolute and one relative atmospheric correction algorithms with uncorrected raw data.
1,502 citations
TL;DR: In this paper, the authors compare a tree with a maximum likelihood classifier using a 1° by 1° global data set and show that the tree's accuracy in classifying a validation dala set is comparable to that when using maximum likelihood (82 per cent).
Abstract: Classification trees are a powerful alternative to more traditional approaches of land cover classification Trees provide a hierarchical and nonlinear classification method and are suited to handling non-parametric training data as well as categorical or missing data By revealing the predictive hierarchical structure of the independent variables, the tree allows for great flexibility in data analysis and interpretation In this Letter, we compare a tree' s performance to that of a maximum likelihood classifier using a 1° by 1° global data sel The tree's accuracy in classifying a validation dala set is comparable to that when using maximum likelihood (82 per cent) The tree also may be used to reduce the dimensionality of data sets and to find those metrics that are most useful for discriminating among cover types
454 citations
TL;DR: In this paper, the authors used a scan-lidar-imager of canopies by echo recovery (SLICER) for a successional sequence of closed-canopy, deciduous forest stands in eastern Maryland.
400 citations
Journal Article•
TL;DR: In this paper, a method was developed for estimating shun-line position from airborne scanning laser data, which allows rapid estimation of objective, GPS-based shoreline positions over hundreds of kilometers of coast, essential for the assessment of large scale coastal behavior.
Abstract: A method has been developed for estimating shun-line position from airborne scanning laser data. This technique allows rapid estimation of objective, GPS-based shoreline positions over hundreds of kilometers of coast, essential for the assessment of large-scale coastal behavior. Shoreline position, defined as the cross-shore position of a vertical shoreline datum, is found by fitting a function to cross-shore profiles of laser altimetry data located in a vertical range around the datum and then evaluating the function at the specified datum. Error bars on horizontal position are directly calculated as the 95% confidence interval on the mean value based on the Student's t distribution of the errors of the regression. The technique was tested using lidar data collected with NASA's Airborne Topographic Mapper (ATM) in September 1997 on the Outer Banks of North Carolina. Estimated lidar-based shoreline position was compared to shoreline position as measured by a ground-based GPS vehicle survey system. The two methods agreed closely with a root mean square difference of 2.9 m. The mean 95% confidence interval for shoreline position was ±1.4 m. The technique has been applied to a study of shoreline change on Assateague Island, Maryland/Virginia, where three ATM data sets were used to assess the statistics of large-scale shoreline change caused by a major 'northeaster' winter storm. The accuracy of both the lidar system and the technique described provides measures of shoreline position and change that are ideal for studying storm-scale variability over large spatial scales.
343 citations