An object-based conceptual framework and computational method for representing and analyzing coastal morphological changes (original) (raw)
Related papers
GEO-SPATIAL TECHNOLOGIES IN SHORELINE ANALYSIS, VARIABILITY AND EROSION
Analysis of shoreline variability and shoreline erosion-accretion trends is fundamental to a broad range of investigations undertaken by coastal scientists, coastal engineers, and coastal managers. Though strictly defined as the intersection of water and land surfaces, for practical purposes, the dynamic nature of this boundary and its dependence on the temporal and spatial scale at which it is being considered results in the use of a range of shoreline indicators. These proxies are generally one of two types: either a feature that is visibly discernible in coastal imagery (e.g., high-water line [HWL]) or the intersection of a tidal datum with the coastal profile (e.g., mean high water [MHW]). Recently, a third category of shoreline indicator has begun to be reported in the literature, based on the application of image-processing techniques to extract proxy shoreline features from digital coastal images that are not necessarily visible to the human eye. Potential data sources for shoreline investigation include historical photographs, coastal maps and charts, aerial photography, beach surveys, in situ geographic positioning system shorelines, and a range of digital elevation or image data derived from remote sensing platforms. The identification of a " shoreline " involves two stages: the first requires the selection and definition of a shoreline indicator feature, and the second is the detection of the chosen Geo-Spatial Technologies In Shoreline Analysis, Variability and Erosion http://www.iaeme.com/IJCIET/index.asp 77 editor@iaeme.com shoreline feature within the available data source. To date, the most common shoreline detection technique has been subjective visual interpretation. Recent photogrammetry, topographic data collection, and digital image-processing techniques now make it possible for the coastal investigator to use objective shoreline detection methods. The remaining challenge is to improve the quantitative and process-based understanding of these shoreline indicator features and their spatial relationship relative to the physical land–water boundary.
Coastal environments globally are recognised for their highly dynamic and unstable nature. The twin processes of erosion and accretion are constantly changing the face of the coastal environments. The Golspie beach situated in Sutherland, Highlands of Scotland is not spared from these processes which have been attributed to natural and anthropogenic factors. To minimise the effects of the rampaging erosions, beach sand feeding has been proposed to protect a section of the beach. To evaluate the success of the proposed project a high resolution digital terrain model (DTM) of the current position of beach in 2014 was necessary. This was achieved with the use of terrestrial laser scanning technique to acquire highly dense point cloud with a 5cm point spacing or resolution over a 1km length of beach. As part of the aims of this study the changes in the beach between 2013 to 2014 was assessed using photogrammetric ally generated DTM from 2013 aerial photographs and DTMs of 2014 from terrestrial laser scanning techniques. These DTMs were used to assess the height and volumetric changes at the study area. The results from the change analysis revealed areas with significant loss and gains in height. Some sections were observed to have experienced height loss of approximately 0.25m to 1.5m especially around the frontage of the south end of the golf course and a section at the frontage of the Kart track. However the trend of height change recorded revealed more of gains than losses. From the volumetric analysis performed the areas with losses in sediments were highlighted. A total change of approximately 30,129.4m3 in sediment volume of the entire study area was recorded out of which the loss and gain represents 30% and 70% respectively. Overall a net gain of approximately 11,929.6m3 was recorded from the sediment budget of the entire beach with a southward movement of these sediments. The general outcome from the study revealed the success of using both techniques in beach studies, as all the aims and objectives of the study was achieved.
Deriving rich coastal morphology and shore zone classification from lidar terrain models
Comprehensive mapping of shore zone morphology supports evaluation of shore habitat, monitoring of environmental hazards, and characterization of the transfer of nutrients between marine- and terrestrial environments. This paper shows how rich shore zone morphological metrics can be derived from lidar terrain models and evaluate the application of lidar to classify shore zone substrate. The utility of lidar methods is tested in comparison with the current best practice method of photo interpretation (i.e., the BC ShoreZone system) on Calvert Island, BC, Canada. Wider applications are considered. Indicators of shore zone morphology (i.e., slope, width, roughness, backshore elevation) are calculated from lidar terrain models for regularly spaced transects perpendicular to the coastline. A combination of boosted regression tree modelling and direct rule application is used to classify shore zone morphology according to the BC ShoreZone system. Classification accuracy is assessed against existing ShoreZone classification data. Shore zone substrate is classified from lidar-derived morphometric indicators with 90% accuracy (5 classes). A full classification which combines substrate with shore width and slope results in lower correspondence (40%; 25 classes) when compared to ShoreZone classes. Differences can likely be attributed, in part, to variation in spatial resolution of elevation-based methods and photo interpretation. It is concluded that lidar data can be used to support characterization of shore zone morphology. Differences in processing and interpretation cause a low direct correspondence with the current image based classification system, but lidar has the advantage of higher resolution, rich terrain information, speed, and an objective and repeatable method for monitoring future change in coastal environments.
LIDAR data to support coastal erosion analysis: the Conero study case
In the last decades, the topic of coastal erosion and the derived risk have been subject of a growing interest for public authorities and researchers. Recent major natural events, such as hurricanes, tsunamis, and sea level rising, called the attention of media and society, underlining serious concerns about such problems. In a high-density populated country such as Italy, where tourism is one of the major economic activities, the coastal erosion is really a critical issue. In April 2010, along a reach of the coast of Ventotene Island, two young students tragically died, killed by a rock fall. This event dramatically stressed public authorities about the effectiveness of structural and non-structural measures for the mitigation of such phenomena. It is clear that an improving of the actual knowledge about coastal erosion is needed, especially to monitor such events and to set alert systems. In the last few years, airborne LIDAR technology led to a dramatic increase in terrain inform...