TopCAT – Topographical Compartment Analysis Tool to analyze seacliff and beach change in GIS

This paper discusses the development of a new GIS extension named the Topographic Compartment Analysis Tool (TopCAT), which compares sequential digital elevation models (DEMs) and provides a quantitative and statistical analysis of the alongshore topographical change. TopCAT was specifically designed for the morphological analysis of seacliffs and beaches but may be applied to other elongated features which experience topographical change, such as stream beds, river banks, coastal dunes, etc. To demonstrate the capabilities of TopCAT two case studies are presented herein. The first case examines coastal cliff retreat for a 500 m section in Del Mar, California and shows that large failures comprised a large portion of the total eroded volume and the average retreat rate does not provide a good estimate of local maximum cliff retreat. The second case investigates the alongshore volumetric beach sand change caused by hurricane Bonnie (1998) for an 85 km section in the Cape Hatteras National Seashore, North Carolina. The results compare well (generally within 6%) with previous investigations. These case studies highlight additional information gained through performing a detailed, discretized analysis using TopCAT.Keywords: Erosion, Topography, LIDAR, Laser scanning, SeacliffKeywords: Erosion, Topography, LIDAR, Laser scanning, Seaclif

vaCATE: A Platform for Automating Data Output from Compartmental Analysis by Tracer Efflux

Compartmental analysis by tracer efflux (CATE) is fundamental to examinations of membrane transport, allowing study of solute movement among subcellular compartments with high temporal, spatial, and chemical resolution. CATE can provide a wealth of information about fluxes and pool sizes in complex systems, but is a mathematically intensive procedure, and there is a need for software designed to fully, easily, and dynamically analyse results from CATE experiments. Here we present vaCATE (Visualized Automation of Compartmental Analysis by Tracer Efflux), a software package that meets these criteria. A robust suite of test cases using CATE datasets from experiments with intact rice ('Oryza sativa' L.) root systems reveals the high fidelity of vaCATE and the ease with which parameters can be extracted, using a three-compartment model and a curve-stripping procedure to distinguish them on the basis of variable exchange rates. vaCATE was developed using Python 2.7 and can be used in most situations where compartmental analysis is required. Funding Statement: This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Ontario Graduate Scholarship Fund (OGS)

Modelling 3D topography by comparing airborne LiDAR data with Unmanned Aerial System (UAS) photogrammetry under multiple imaging conditions

This study presents the effect of image data sources on the topographic modelling of part of the National Trust site located at Weston-Super-Mare, Bristol, United Kingdom, covering an approximate area of 1.82 hectares. The accuracy of the DEM generated from 1m resolution and 2m resolution LiDAR data together with the accuracy of the DEM generated from the UAV images acquired at different altitudes are analysed using the 1 m LiDAR DEM as reference for the accuracy assessment. Using the NSSDA methodology, the horizontal and vertical accuracy of the DEMs generated from each of the four sources were computed while the paired sample t-test was conducted to ascertain the existence of statistically significant difference between the means of the X, Y, and Z coordinates of the check points. The result obtained shows that with a RMSE of -0.0101499 and horizontal accuracy of -0.175674686m, the planimetric coordinates extracted from 2 m LiDAR DEM were more accurate than the planimetric coordinates extracted from the UAV based DEMs while the UAV based DEMs proved to be more accurate than the 2m LiDAR DEM in terms of altimetric coordinates, though the DEM generated from UAV images acquired at 50 m altitude gave the most accurate result when compared with the vertical accuracy obtained from the DEM generated from UAV images acquired at 30 m and 70 m flight heights. These findings are also consistent with the result of the statistical analysis at 95% confidence interval

Unmanned aerial vehicle large scale mapping for coastal erosion assessment

Most of the time, many countries in tropical region are covered by cloudwhich obstruct the acquisition of high resolution optical image from satellite. Thus,the application of large scale mapping for coastal erosion assessment is difficult to becarried out. The unmanned aerial vehicle (UAV) can be used for acquisition of highresolution image due to its ability of flying at low altitudes and under cloud cover.This study aims to improve the methodology of data acquisition for assessing erodedcoastal area by using UAV system designed for large scale mapping. The objectivesof this study are (i) to improve the methodology of data acquisition for large scalecoastal erosion assessment using UAV with rapid and low cost, (ii) to assess theaccuracy of the digital photogrammetric products obtained with different groundcontrol points (GCP) configurations and flying altitude, and (iii) to identify andassess coastal areas due to erosion based on the large-scale orthophoto produced.Two improved methods were introduced in this study: (i) rapid data acquisition andprocessing, low cost and accurate mapping using UAV, and (ii) modification of theend point rate (EPR) and linear regression rate (LRR) calculation methods byincluding two new parameters namely the sea water and wave level to detectcoastline changes. The modified EPR and LRR methods in detecting the coastlinechanges of Crystal Bay, Alai, Melaka and Kampung Seri Pantai, Mersing, Johorwere evaluated through statistical model, namely t-test and compared with otherstudies of similar area for validation and verification. Several configurations of GCP,check points (CP) and flying altitude were used to produce the digital elevationmodel (DEM) and orthophoto which were then processed photogrammetrically.Subsequently, the coastal erosion assessment was performed and the coastlinechanges of private properties, buildings and residential areas was identified. Theresults show that the best GCP configuration to produce coastal erosion mappingscale of 1:14000 is 25 points. Meanwhile, the best flying altitude is 300m withaccuracies of ±0.002m, ±0.004m and ±0.389m in Northing, Easting and Heightrespectively. Furthermore, this study shows that most of the coastline, privateproperties, buildings and residential areas are affected by the coastal erosion. Basedon the modified EPR and LRR calculation methods in determining the coastlinechanges, it is evident that the coastline change rate is significant. In conclusion, thisstudy shows that the UAV system offers many advantages such as its ability to fly atlow altitude, low cost, rapid data acquisition and processing in detecting coastlinechanges and accurate results

Paving the way for terrestrial laser scanning assessment of road quality

With the growing trend in use of 3D laser scanning technology for data collection, it is important to study the various potential applications of this revolutionary technology. One such application is the measurement of road roughness at both large and small scales. At larger extents, terrestrial laser scanning (TLS) is compared to several current techniques to measure road profiles including digital levels, inclinometers, and inertial profilers. An overall indicator of roughness (e.g. International Roughness Index, IRI) can be obtained from these road profiles and is used by state DOTs to determine the pavement quality. Since TLS is able to collect a large, dense set of data relatively quickly, this technology could provide states with an additional tool to both measure pavement roughness and collect data for the entire roadway. TLS has the added benefit of being able to generate multiple profiles across the roadway efficiently. At a fine scale, micron resolution 3D laser scanners can be utilized to determine the influence of asphalt mix designs on the roughness of the pavement. Of particular interest is the selection of predominant aggregate size within the mix. Results showed that TLS can determine pavement profiles and comparable IRI results to those from current methods. The elevation values collected within the profile were accurate within expected ranges. However, cross correlations, which take into account the location of the roughness, were poor, indicating that TLS is not an effective method to determine a reference profile. TLS was used to determine the cross slopes across the roadway, something that cannot be done with data from an inclinometer or inertial profiler

Beach volumetric analysis and wave forcing along an Irish beach system

Dissertação de mestrado, Geomática, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014Five Finger Strand, a bedrock-framed beach located between Five Finger rock and the mouth of Trawbreaga Bay, Republic of Ireland, appears to experience high temporal and spatial variability in erosion and accretion because the coast is forced by multiple mechanisms that operate over different time scales (Cooper et al., 2007). To identify all states the beach can present, their frequency of occurrence and dynamics, it the study of beach profiles was implemented in which beach volumetric analysis was used to determine and predict beach evolution. Additionally incident waves were analysed and statistical analysis applied on these. Owing to data complexity, a Geographic Information System (GIS) tool – BeachPROG – was developed to facilitate data analysis. As input it uses Differential Global Positioning System (DGPS) data and outputs Digital Elevation Models (DEMs), beach volumes, profiles and respective areas and slopes, through Python script. In general, this tool revealed good results, as the data automation, visualisation, spatial consultation, and spatial analysis can be accessed in a much more intuitive way than through existing methods. Equally, this tool can serve as a methodological base for other investigations, presenting a fully commented, easy script structure that enables further modifications and/or script accretions. Data from the BeachPROG tool, were compared against hydrodynamic data at the site. The existence of variations in beach behaviour caused by wave forcing was clearly evident. However, in some cases it was equally possible to verify that even being exposed to conditions capable of causing significant changes, the beach remained stable. A deep knowledge on how waves and inlet dynamics interact with the beach, changing its behaviour, was however, not the main aim of this thesis, since the main goal was to develop and test the GIS based tool. Previous studies analysing similar forcing agents showed different beach behaviours, for the study area, indicating that further and more detailed studies must be performed.A praia Five Finger Strand, de estrutura rochosa e compreendida entre a rocha Five Finger e a barra de maré do Trawbreaga (M. C. O’ Connor, Cooper, & McKenna, 2009), República da Irlanda, evidencia ser condicionada por diversos mecanismos, causando variabilidade sedimentar temporal e espacial (Cooper et al., 2007). Para a correta identificação dos comportamentos que a praia pode apresentar, respetiva frequência e dinâmica com que ocorrem, foi implementado o estudo de perfis de praia, tendo-se recorrido às análises volumétricas para determinar a sua evolução. Adicionalmente, estudou-se a atuação das ondas incidentes e implementou-se uma análise estatística. Devido à complexidade dos dados, foi desenvolvida a ferramenta SIG – BeachPROG – para facilitar o tratamento de dados. Esta ferramenta usa dados DGPS para originar MDEs, perfis de praia, volumes e respetivas áreas, através de códigos em Python. No geral, esta ferramenta revelou estar apta a desenvolver as tarefas definidas, sendo que a automatização dos dados, visualização, consulta e análise espacial podem ser executadas de forma bastante intuitiva. A ferramenta está igualmente apta a servir como base metodológica para outras investigações, apresentando um código totalmente comentado e de fácil estrutura, permitindo assim futuras modificações. Após obtenção dos dados com a ferramenta BeachPROG, foram realizadas comparações com dados da agitação marítima. A existência de variações comportamentais da praia causadas por alterações na atuação das ondas foi bastante evidente. No entanto, em alguns casos foi igualmente possível verificar que, mesmo existindo todas as condições capazes de provocar alterações significativas na praia, esta manteve-se estável. Não foi possível, nesta dissertação, saber em detalhe como estes dois mecanismos atuam na praia e qual o agente predominante para cada condição, visto que o objetivo principal foi o desenvolvimento e teste da ferramenta. Estudos anteriores revelaram que, para condições hidrodinâmicas semelhantes, diferentes comportamentos da praia foram obtidos, reforçando a necessidade da realização de estudos mais detalhados