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Although originally developed for military purposes, Global Navigation Satellite Systems have become indispensable for an ever-growing range of civil and scientific applications such as cartography, cadastral and land information systems, transport systems, precision agriculture, self-driving vehicles, rescue missions, etc. The accuracy of positioning by means of GNSS, however, is affected by atmospheric distortions of the GNSS signals as well as by the characteristics of the receiver (e.g. number of channels, firmware, etc.), local external influences (e.g. reflective surfaces, obstructions, electromagnetic distortions, etc.), and the system used to correct these distortions (e.g. SBAS, RTK, RTK-network, post-processing, etc.). Hence, to predict the accuracy of the positioning, it is important to understand the degree of robustness of the system (receiver and method) in terms of the degree in which it is affected by ionospheric conditions and local external influences. For this research the system consisted of a Septentrio ALTUS NR3 GNSS receiver in combination with the Flemish RTK-network FLEPOS, Belgium. To assess the accuracy and its variations, measurements in varying external circumstances, were performed according to the of ISO 17123-8 standard during the period November 2021 - April 2022. The results show that the system is very robust for the influence of the I95 index and the location specific parameters: proximity of high voltage cables and windmills. However, the distance to the nearest reference station and the number of visible satellites can affect the precision. Further research is necessary to assess the influence of other parameters.

The measurement of surface moisture on beaches is vital for studying aeolian sand transport mechanisms, but existing techniques are not adequate for monitoring the surface moisture dynamics over a substantial beach section. In this study, we investigated the suitability of a new remote sensing method to monitor the spatiotemporal variation in surface moisture on a sandy beach using a long-range static terrestrial laser scanner (TLS). The TLS was permanently deployed on top of a 42 m high building overlooking the study site at Ostend-Mariakerke, Belgium. Considering the effect of target surface roughness on the intensity and the laboratory’s length limitation, a new intensity correction method is proposed which only uses the field point cloud data measured on a homogenous beach surface (without time-consuming indoor experiments). Based on the corrected intensity data, the relation of the beach surface moisture to the corrected intensity was modeled by an exponential model with a correlation-coefficient squared of 0.92. A moisture estimation model was developed which can directly derive the beach surface moisture from the original intensity data of the TLS with a standard error of 2.27%. The hourly surface moisture dynamics across two tidal cycles on the beach were investigated as a case study, in which the point clouds derived from corresponding unmanned aerial vehicle (UAV) imagery are utilized to improve the calculation accuracy of the incidence angles of TLS point clouds at long distances. Results reveal that, after the intensity correction, the long-range static TLS is an extremely suitable technique to monitor the surface moisture dynamics (daytime and nighttime) over a substantial beach section (hundreds of meters) at a high scanning frequency (minutes to hours).

The digital age has brought about an explosion in the growth of data, of which data with a geographical component stands out. Proper use of geographical data comes with the need for correct coordinate reference systems (CRSs). They are considered the ultimate binder for interoperability between geospatial data actors and stakeholders. Moreover, CRSs are crucial for the visual and analytical integration of geospatial data from disparate data sources. However, CRSs might be—for numerous reasons—incorrectly assigned or even missing. The result is a time-consuming study of the map, literature, and available resources to ultimately find the alleged right CRS. This study provides a summary of prevailing resources from national mapping agencies of some European countries to address the above problem. Secondly, and most importantly, is the development of an open-source Python-based software package. This software package aims to accurately estimate the best candidate CRS, given a tuple of coordinates at a priori an approximately known location. It is controlled by geocoding the known location and intersecting the resulting coordinate with the bounding box of all CRSs in the EPSG-database. An in-depth review of CRS tools by mapping authorities reveals, in particular, limitations concerning the countries’ spatial areas, in combination with often required know-how of local CRSs. To address these shortcomings, our tool is developed to enable a more generic extraction of CRSs for any given location worldwide. Testing proved successful for 30 different maps, with a grid present on the map and the CRS of the map being included in the EPSG-database.

Intertidal polychaete aggregations may be protected in the European Union under the Habitats Directive framework as reef habitats. Remote reef mapping remains challenging due to severe and dynamic conditions, as well as cover and spatial resolution requirements. This study (1) evaluated kite aerial photography and low-altitude digital photogrammetry to map and monitor intertidal aggregations of a sessile tube-building polychaete, Lanice conchilega (L. conchilega), and (2) developed a protocol for its remote identification. Monthly campaigns yielded 12 aerial image sets which were processed using structure-from-motion into high-precision digital terrain models and orthophoto mosaics. Maximum likelihood classification distinguished L. conchilega from bare sediment with an accuracy of 70% ± 23.2%. Aggregations were delineated by extracting elements of positive elevation from local difference models. The method has proven useful to detect high-value aggregations, distinguishing these consistently. Nevertheless, systematic biases were present during delineation, and further characterisation of reference aggregations may improve detection.

Data and metadata products based on intensive terrestrial gravity measurements covering the Belgian territory have been established compliant to the new ISO19115‐1 profile for gravity‐related data. A short historical introduction on gravity measurements on the Belgian territory is presented, starting with the first gravity measurement in 1892. This paper focuses on gravity data acquired after 1971, which marks the adoption of IGSN71 as a reference for the world network by the International Association of Geodesy (IAG). Next to a complete dataset containing all Belgian gravity data, the available gravity data were reduced to the corresponding measurement campaign, enabling determination of specific metadata (e.g. used gravimeter, tide system parameters, time of acquisition, etc.). New gravity and spirit levelling measurements were executed by the Royal Observatory Belgium and the National Geographic Institute (Federal Mapping Agency) to validate the g‐value at the historical reference base station ‘Carte du Ciel’ in Brussels. Taking into account the instrumental errors and the varying ground water content, the retrieved data are validated and approved for use in further research.

National geodetic reference systems can be continuously monitored using applications of Global Navigation Satellite Systems (GNSS). Within these reference systems, Continuously Operating GNSS Reference Stations (CORSs) are often employed to provide 24/7 satellite tracking data. Understanding the influence of the surroundings of a CORS on the recorded satellite tracking data is indispensable for quality analysis of both acquired data and station location suitability. One of the main sources of inaccurate tracking data is the result of the combined reception of direct as well as indirect, environment-reflected satellite signals by the CORS, in which the latter can be considered interference compromising the signal’s accuracy. The magnitude of this interference is usually evaluated by the Signal-to-Noise Ratio (SNR), a parameter stored by default in the RINEX interchange format for raw GNSS data. The technique of GNSS Interferometric Reflectometry (GNSS-IR) exploits the availability of the SNR data and has been frequently used for applications such as soil moisture monitoring, detection of vegetation water content, measuring snowfall or determining water levels. In this research, we propose to employ GNSS-IR to investigate the effect of the surrounding on a CORS in order to evaluate station location suitability. More specifically, this will be done by using the signal to estimate the Reflector Height (RH), which depends on the reflector roughness (i.e. the roughness of the surface surrounding the CORS). The quality of this estimation will be validated by comparing with the actual measurement of the RH of the CORS on site.In our approach, a statistically sound method is developed quantifying the stability of the RH determination. The proposed methodology consists of using Lomb-Scargle periodograms to select the dominant oscillation frequency of each satellite track SNR data, followed by an analysis and filtering of the peak amplitudes. This leads to the analysis product: number of significant peak amplitudes for an individual CORS over (sub-)daily timeframes. With historical data covering long time periods, statistical analysis of the (sub-)daily timeseries allows for reviewing the station location suitability. In Belgium, CORS are located on two typical positions: in Flanders, the 32 antennas are mainly installed on rooftops of buildings; in Wallonia, the 23 antennas are installed on a concrete pole next to highways. There is no evidence of one choice of station position being more suitable than the other. However, cars are known to be an important factor in signal reflections. In our analysis of station suitability, the effect of cars passing by on the highway near a Walloon CORS, but also movements on, e.g., parking lots next to buildings with a rooftop CORS, will be investigated. With the developed methodology, guidelines for station location selection could be further developed, together with a system to continuously monitor CORS position suitability using GNSS-IR, triggering a warning when significant changes in the environment changes the local reflectometry fingerprint.

Highlights • High-resolution beach surface moisture estimation from the LiDAR intensity data. • No need to calibrate the intensity data in advance based on the Machine Learning. • Detailed investigation of the impacts of SVR training samples’ size and density., Beach Surface Moisture (BSM) is a key attribute in the coastal investigations of land-atmospheric water and energy fluxes, groundwater resource budgets and coastal beach/dune development. In this study, an attempt has been made for the first time to estimate BSM from terrestrial LiDAR intensity data based on the Support Vector Regression (SVR). A long-range static terrestrial LiDAR (Riegl VZ-2000) was adopted to collect point cloud data of high spatiotemporal resolution on the Ostend-Mariakerke beach, Belgium. Based on the field moisture samples, SVR models were developed to retrieve BSM, using the backscattered intensity, scanning ranges and incidence angles as input features. The impacts of the training samples’ size and density on the predictive accuracy and generalization capability of the SVR models were fully investigated based on simulated BSM-intensity samples. Additionally, we compared the performance of the SVR models for BSM estimation with the traditional Stepwise Regression (SR) method and the Artificial Neural Network (ANN). Results show that SVR could accurately retrieve the BSM from the backscattered intensity with high reproducibility (average test RMSE of 0.71% ± 0.02% and R2 of 0.98% ± 0.002%). The Radial Basis Function (RBF) was the most suitable kernel for SVR model development in this study. The impacts of scanning geometry on the intensity could also be accurately corrected in the process of estimating BSM by the SVR models. However, compared to the SR method, the predictive accuracy and generalization performance of SVR models were significantly dependent on the training samples’ coverage, size and distribution, suggesting the need for the training samples of uniform distribution and representativeness. The minimum size of training samples required for SVR model development was 54. Under this condition, SVR performed similarly to ANN with a test RMSE of 1.06%, but SVR still performed acceptably (with an RMSE of 1.83%) even using extremely few training samples (only 16 field samples of uniform distribution), far better than the ANN (with an RMSE of 4.02%).

Sustainable forest management heavily relies on the accurate estimation of tree parameters. Among others, the diameter at breast height (DBH) is important for extracting the volume and mass of an individual tree. For systematically estimating the volume of entire plots, airborne laser scanning (ALS) data are used. The estimation model is frequently calibrated using manual DBH measurements or static terrestrial laser scans (STLS) of sample plots. Although reliable, this method is time-consuming, which greatly hampers its use. Here, a handheld mobile terrestrial laser scanning (HMTLS) was demonstrated to be a useful alternative technique to precisely and efficiently calculate DBH. Different data acquisition techniques were applied at a sample plot, then the resulting parameters were comparatively analysed. The calculated DBH values were comparable to the manual measurements for HMTLS, STLS, and ALS data sets. Given the comparability of the extracted parameters, with a reduced point density of HTMLS compared to STLS data, and the reasonable increase of performance, with a reduction of acquisition time with a factor of 5 compared to conventional STLS techniques and a factor of 3 compared to manual measurements, HMTLS is considered a useful alternative technique.

The North Sea is a shallow sea that forms a complex physical system. The nonlinear interaction of the astronomical tides, varying wind fields and varying pressure systems requires appropriate approaches to be described accurately. An application based on the advanced numerical model Regional Ocean Modeling System (ROMS) was newly developed by the authors, tailored to simulate these hydrodynamic processes in the North Sea and the Belgian Continental Shelf, which is the area of particular interest in the present study. The purpose of this work is to develop and validate a state-of-the-art three-dimensional numerical model to form the basis of a compound operational and forecasting tool for the Belgian coastal zone. The model was validated with respect to water levels and temperature. Validation for astronomical tides was accomplished through the comparison of the principal constituents between the model results and observations at a number of tidal gauges in Belgium and other countries. A statistical analysis of the results showed that the model behaves as expected throughout the North Sea. The model response to the varying meteorological conditions was also validated using hindcast data for 2011 as input. In this case, the comparison between observed and modelled water levels showed a good agreement with average RMSE in Belgium 9.5 cm. Overall, the added value of this work is the development of an independent model for validation and comparison with other models and which can be used as an efficient tool for operational and forecasting purposes.

Surface moisture plays a key role in limiting the aeolian transport on sandy beaches. However, the existing measurement techniques cannot adequately characterize the spatial and temporal distribution of the beach surface moisture. In this study, a mobile terrestrial LiDAR (MTL) is demonstrated as a promising method to detect the beach surface moisture using a phase-based Z&F/Leica HDS6100 laser scanner mounted on an all-terrain vehicle. Firstly, two sets of indoor calibration experiments were conducted so as to comprehensively investigate the effect of distance, incidence angle and sand moisture contents on the backscattered intensity by means of sand samples with an average grain diameter of 0.12 mm. A moisture estimation model was developed which eliminated the effects of the incidence angle and distance (it only relates to the target surface reflectance). The experimental results reveal both the distance and incidence angle influencing the backscattered intensity of the sand samples. The standard error of the moisture model amounts to 2.0% moisture, which is considerably lower than the results of the photographic method. Moreover, a field measurement was conducted using the MTL system on a sandy beach in Belgium. The accuracy and robustness of the beach surface moisture derived from the MTL data was evaluated. The results show that the MTL is a highly suitable technique to accurately and robustly measure the surface moisture variations on a sandy beach with an ultra-high spatial resolution (centimeter-level) in a short time span (12 × 200 m per minute).

Montreuil, A-L.; Chen, M.; Brand, E.; Strypsteen, G.; Rauwoens, P.; Vandenbulcke, A.; De Wulf, A.; Dan, S., and Verwaest, T., 2018. Dynamics of surface moisture content on a macro-tidal beach. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 206–210. Coconut Creek (Florida), ISSN 0749-0208. Surface moisture content is a significant factor controlling aeolian sand transport. It is influenced by atmospheric, marine and sub-surface processes. Although several studies reported direct links in surface moisture content with the processes responsible for those variations, there is still a lack of understanding of its dynamic on a macro-tidal beach. This study aims to investigate spatial and temporal dynamics in the surface moisture content of a macro-tidal beach, and to determine the relative importance of factors controlling these. A field experiment was per...

Worldwide, flood events frequently have a dramatic impact on urban societies. Time is key during a flood event in order to evacuate vulnerable people at risk, minimize the socio-economic, ecologic and cultural impact of the event and restore a society from this hazard as quickly as possible. Therefore, detecting a flood in near real-time and assessing the risks relating to these flood events on the fly is of great importance. Therefore, there is a need to search for the optimal way to collect data in order to detect floods in real time. Internet of Things (IoT) is the ideal method to bring together data of sensing equipment or identifying tools with networking and processing capabilities, allow them to communicate with one another and with other devices and services over the Internet to accomplish the detection of floods in near real-time. The main objective of this paper is to report on the current state of research on the IoT in the domain of flood detection. Current trends in IoT are identified, and academic literature is examined. The integration of IoT would greatly enhance disaster management and, therefore, will be of greater importance into the future.

The use of mobile pedestrian wayfinding applications is gaining importance indoors. However, compared to outdoors, much less research has been conducted with respect to the most adequate ways to convey indoor wayfinding information to a user. An explorative study was conducted to compare two pedestrian indoor wayfinding applications, one text-based (SoleWay) and one image-based (Eyedog), in terms of mental effort. To do this, eye tracking data and mental effort ratings were collected from 29 participants during two routes in an indoor environment. The results show that both textual instructions and photographs can enable a navigator to find his/her way while experiencing no or very little cognitive effort or difficulties. However, these instructions must be in line with a user’s expectations of the route, which are based on his/her interpretation of the indoor environment at decision points. In this case, textual instructions offer the advantage that specific information can be explicitly and concisely shared with the user. Furthermore, the study drew attention to potential usability issues of the wayfinding aids (e.g. the incentive to swipe) and, as such, demonstrated the value of eye tracking and mental effort assessments in usability research.

Sediment transport is a key element in intertidal beach morphodynamics, but measurements of sediment transport are often unreliable. The aim of this study is to quantify and investigate cross-shore sediment transport and the resulting topographic changes for a tide-dominated, sandy beach. Two fortnight-long field experiments were carried out during which hydrodynamics and sediment dynamics were measured with optical and acoustic sensors, while the beach topography was surveyed with a permanent terrestrial laser scanner. Suspended sediment was generally well-mixed and currents were largest at approximately 1.5 m above the bed, which resulted in a peak in sediment transport at 1/3 of the high tide level. The mean transport direction was onshore during calm conditions (wave height &lt, 0.6 m) thanks to tidal currents and offshore during energetic conditions due to undertow. Oscillatory transport was always onshore because of wave asymmetry but it was subordinate to mean transport. The intertidal zone showed an alternation of erosion and accretion with formation of morphological features during energetic (no storm) conditionsand smoothening of the morphology during calm conditions. A good qualitative and quantitative agreement was found between the daily cross-shore suspended load and beach volume changes, especially during calm conditions.

Landmarks are ideal wayfinding tools to guide a person from A to B as they allow fast reasoning and efficient communication. However, very few path-finding algorithms start from the availability of landmarks to generate a path. In this paper, which focuses on indoor wayfinding, a landmark-based path-finding algorithm is presented in which the endpoint partition is proposed as spatial model of the environment. In this model, the indoor environment is divided into convex sub-shapes, called e-spaces, that are stable with respect to the visual information provided by a person’s surroundings (e.g. walls, landmarks). The algorithm itself implements a breadth-first search on a graph in which mutually visible e-spaces suited for wayfinding are connected. The results of a case study, in which the calculated paths were compared with their corresponding shortest paths, show that the proposed algorithm is a valuable alternative for Dijkstra’s shortest path algorithm. It is able to calculate a path with a minimal amount of actions that are linked to landmarks, while the path length increase is comparable to the increase observed when applying other path algorithms that adhere to natural wayfinding behaviour. However, the practicability of the proposed algorithm is highly dependent on the availability of landmarks and on the spatial configuration of the building.

Transforming relations between stratigraphic units of an archaeological excavation to a formal model like the Harris Matrix is a challenging task. Especially when the number of stratigraphic units is large or when spatiotemporal relations are complex, such models are difficult to generate. This paper describes a novel procedure for the automated construction of Harris Matrices involving the use of open source database software programs and tools. The procedure is based on an algorithm for the detection of spatial relations between stratigraphic units. For each stratigraphic unit (represented by commonly available 2D polygons), all possible top-down spatial relations are defined. These large series of relations are then iteratively validated, retaining a limited number of topological coherent sequences. These relations are required for the definition of stratigraphic sequences. To facilitate the presentation of resulting sequences, a stratigraphic diagram is incorporated into a graphical user interface on top of a geodatabase management system and web feature service (WFS). This interface is supplemented with attributes of each stratigraphic unit and with a virtual representation in an embedded 2D map viewer and 3D viewer. The link between sequences and cartographic representations of stratigraphic units by the underlying system enables interactions between various elements of the dataset while taking into account 2D and 3D spatial information, stratigraphic relations and attribute displays. Three theoretical datasets are used to develop and test the workflow. Furthermore, a reference dataset is used to validate this workflow. We find that expert knowledge remains indispensable for the interpretation and validation of both data sources and results. Nevertheless, the robustness of the results of this study illustrate the potential of the proposed procedure for use in automated Harris Matrix construction based on sequences of stratigraphic unit polygons. In employing this procedure, systems may facilitate the management of archaeological (spatiotemporal) data in cost- and time-efficient research infrastructures.

In this paper, the use of a tidal buoy, equipped with a GNSS, is assessed. The prediction of the tide in the North Sea area is performed by a network of coastal tidal gauges. Long term measurements by these gauges are used to derive tidal constituents and the construction of tidal prediction tables for each separate measurement location. To estimate the tide between these locations, an interpolation is required. However, the quality of this calculation is heavily reduced for offshore predictions. The aim of this research is to deal with this challenge by the deployment of GNSS-buoys on full sea. The focus is on the data processing and the analysis of meteorological influences on the data quality. In this context, a strong correlation between meteorological parameters and the ability to calculate a fixed position will be demonstrated. Based on the results of two separated measurement campaigns, it is stated that the developed data acquisition technique results in highly accurate elevation measurement.

Knowledge of aeolian sediment dynamics over an elevated berm with an upwind topographic obstacle is rather scarce and is of utmost importance for understanding aeolian transport from beach to dunes. This study reports on a field experiment designed to carry out simultaneous measurements of wind and aeolian sediment dynamics across a human-constructed berm with a steep seaward cliff backed by a dyke. In front of the dyke, a trench is excavated to prevent aeolian sand being blown to the hinterland. Two sets of measurements were carried out, one with low-moderate (6–7 m/s) oblique onshore wind and one with high velocity winds directly onshore (12–13 m/s). Due to the irregularity of topography upwind of the berm, boundary layer flow dynamics are dramatically different and influenced the sediment dynamics locally. Maximum transport was achieved at a distance of 20 to 35 m downwind from the cliff. Downwind sediment transport was characterized with an overshoot during the oblique onshore wind event. Sand mass flux rapidly increases towards a maximum value followed by a decrease to a lower equilibrium value which was approximately half of the maximum mass flux. The evolution of the vertical flux profiles downwind caused the exponential decay rate β to increase with increasing distance further away from the cliff, until an equilibrium decay rate is achieved. The measurements presented herein show that the distribution of particle trajectories for different transport events changes similar downwind of the cliff until it is stable.

Montreuil, A-L.; Chen, M.; Brand, E.; De Wulf, A.; De Sloover, L.; Dan, S., and Verwaest, T., 2020. Early-stage aeolain dune development and dynamics on the upper-beach. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 336–340. Coconut Creek (Florida), ISSN 0749-0208.Early-stage aeolian protodunes, or ephemeral dunes, are ubiquitous features on the upper-beach, acting as requisite precursors to fully developed dunes. Their formation during high energy aeolian sand transport events plays an important role in the beach morphodynamics and sediment budget. However, little is documented about their life cycle from generation to degeneration as well as their interactions with environmental factors. This study takes the opportunity of the advance in high resolution terrestrial laser scanning technique to acquire morphological changes at an appropriate frequency and spatial resolution to characterize ephemeral dune dynamics. A 1.5 days set of hourly laser scans indicates the development of a field of protodunes with a height ranging from 0.15 to 0.42 m concentrated on the upper-beach. They develop in a few hours under oblique alongshore winds above 7 m/s. The results also show that the protodunes migrate relatively fast with an average rate up to 1.1 cm/hour. Spatial and temporal variability of their morphological characteristics occur across the upper-beach. The morphological changes reflect the pattern of the development and behaviour of the protodune field which seem to be self-organized within a complex system controlled by the interactions between the bedforms themselves, environmental factors and aeolian sediment transport. Our findings highlight the importance of quantifying processes at spatio-temporal scales for monitoring protodune morphology.

Floods cause major disruptions to energy supply and transportation facilities and lead to significant impacts on the society, economy, and environment. As a result, there is a compelling need for resilience and adaptation against extreme flood events under a changing climate. An accurate focal priority analysis of how societies can adapt to these changing events can provide insight into practical solutions. Besides the social, ecological, and cultural impact assessments of floods, an accurate economic impact analysis is required to define priority zones and priority measures. Unfortunately, studies show that economic impact assessments can be highly inaccurate because of the margin of error in economic value estimation of residential and industrial buildings, as they account for a large part of the total economic damage value. Therefore, tools that can accurately estimate the maximum economic damage value (or replacement value) of residential and industrial buildings are imperative. This paper outlines a methodology to estimate the maximum economic value of buildings by using a data extraction algorithm for Energy Performance Certificates (EPC), through which the replacement value can be calculated for all of the buildings in Flanders, and in addition, across Europe.

This article presents a newly developed procedure for the classification of airborne laser scanning (ALS) point clouds, based on binomial logistic regression analysis. By using a feature space containing a large number of adaptable geometrical parameters, this new procedure can be applied to point clouds covering different types of topography and variable point densities. Besides, the procedure can be adapted to different user requirements. A binomial logistic model is estimated for all a priori defined classes, using a training set of manually classified points. For each point, a value is calculated defining the probability that this point belongs to a certain class. The class with the highest probability will be used for the final point classification. Besides, the use of statistical methods enables a thorough model evaluation by the implementation of well-founded inference criteria. If necessary, the interpretation of these inference analyses also enables the possible definition of more sub-classes. The use of a large number of geometrical parameters is an important advantage of this procedure in comparison with current classification algorithms. It allows more user modifications for the large variety of types of ALS point clouds, while still achieving comparable classification results. It is indeed possible to evaluate parameters as degrees of freedom and remove or add parameters as a function of the type of study area. The performance of this procedure is successfully demonstrated by classifying two different ALS point sets from an urban and a rural area. Moreover, the potential of the proposed classification procedure is explored for terrestrial data.

The aim of the current study is to examine the role played by Thorikos within the Laurion silver mining area from the perspective of metallurgical activities during the Classical and Early Hellenistic periods. Because water availability directly determines the production output of metallurgical workshops, a hydrological analysis of the area is an ideal tool to enhance our understanding of this issue. On a large scale, hydrological modelling is accomplished through the analysis of runoff water accumulation; on a small scale, a water balance model is used to simulate the operated water supply system for industrial purposes, more specifically the purifying of silver ores in washeries. Also, the impact of cistern location on its effectiveness and usability for silver processing is explored. The two focus areas are the Velatouri Hill, where the site of Thorikos is located, and the Soureza Valley, which is situated in the centre of the Laurion. In each area a number of ore washing workshops were chosen to study in more detail. Through the region-wide hydrological and archaeological analysis, it could be shown that the Thorikos workshops contrast sharply with the Soureza ones. The latter relied on ephemeral streams which were consolidated and tapped by large cisterns, thus creating a water stock that was more than sufficient to bridge the dry periods of the year. The former relied on the harvesting of limited runoff during heavy rain events, which in many cases did not provide a sufficient water stock. Furthermore, water supply strategies in Thorikos were not as well-considered in comparison to Soureza. This leads to the conclusion that Thorikos could have never been the large scale processing site Soureza was and, when combined with the small-scale analysis, the site must have had a distinctively more ad hoc character.

Floods can cause damage to transportation and energy infrastructure, disrupt the delivery of services, and take a toll on public health, sometimes even causing significant loss of life. Although scientists widely stress the compelling need for resilience against extreme events under a changing climate, tools for dealing with expected hazards lag behind. Not only does the socio-economic, ecologic and cultural impact of floods need to be considered, but the potential disruption of a society with regard to priority adaptation guidelines, measures, and policy recommendations need to be considered as well. The main downfall of current impact assessment tools is the raster approach that cannot effectively handle multiple metadata of vital infrastructures, crucial buildings, and vulnerable land use (among other challenges). We have developed a powerful cross-platform flood impact assessment tool (FLIAT) that uses a vector approach linked to a relational database using open source program languages, which can perform parallel computation. As a result, FLIAT can manage multiple detailed datasets, whereby there is no loss of geometrical information. This paper describes the development of FLIAT and the performance of this tool.

Monitoring of measurements needs to be supported by a thorough knowledge of the achievable accuracy of the measurement equipment and the processing methodology. This study on ovalization monitoring with laser scanning in tunnels under construction focused on fast-performing laser scanners and their achievable accuracy. This research also investigated the optimum smoothing level of the laser scanning data to achieve the best estimates of ovalization. The experimentally based standard deviations indicate that the used phase-based laser scanner delivers highly accurate results with standard deviations between 0.34 and 0.58 mm, depending on the applied smoothing level. In this research, this laser scanner was used, together with a [x – 0.008 rad; x + 0.008 rad] smoothing interval on the calculated radius values to meet the accuracy requirement requested by the client (0.5 mm), even when using multiple setups. Another used type of laser scanner (pulse-based) also delivers standard deviations around thi...

The 6-km-long Liefkenshoek rail tunnel creates a new freight connection in the Port of Antwerp (Belgium) by crossing the River Scheldt and Port Canal. The water level variation of the river, corresponding to the tides of the North Sea, proved to be a nonnegligible load state for the tunnel lining. This paper reports how the structural response of the Liefkenshoek tunnel to the tidal fluctuations could be identified, thanks to the various components of the complementary monitoring program, consisting of strain, ovalization, and leveling measurements. First, an in-depth study on the methodology of the applied monitoring procedures is presented. Next, results show that the tidal effect causes an oscillating vertical displacement of the tunnel lining up to 10 mm between low and high tide. Outside the river boundaries, no significant tidal influence is found, and the transition zone between the stable tunnel section and the moving part below the river appears to be constrained to a relatively small tun...

In order to improve European biodiversity, natural habitats need to be restored and improved within a large European network of protected areas (Natura 2000). Therefore, agricultural land often needs to be converted to nature. Lowering soil nitrogen and phosphorus levels appears to be a necessary prerequisite for a successful restoration. To select which agricultural fields are most suitable for conversion to natural habitats, large and expensive soil monitoring campaigns are actually executed in situ. n this paper, it is demonstrated that hyperspectral satellite imagery, acquired by the EO-1 Hyperion sensor, has a large potential to substitute the current method. This is demonstrated in a qualitative regional study, where ground water analyses are used to derive the correlation between nutrient concentrations and spectral bands. Additionally, a pair-wise index is calculated for each band and compared with in-situ values. For this study, it is stated that the concentration of nutrients can be explained by a linear model using at least one or two spectral bands, with R2 correlations between 0.4 and 0.7.