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Tasaduak S.,Kasetsart University | Weesakul S.,Hydro and Agro Informatics Institute
Journal of Coastal Conservation | Year: 2016

A dynamic equilibrium bay (DEB) is an embayment with continuous sediment supply and its shoreline planform can remain stable over a long period of time without erosion or accretion. For coastal conservation of sandy headland-bay beaches (HBB), the concept of using a static equilibrium bay (SEB) is well known, but that for DEB has received little attention. Moreover, an empirical equation for the stability of a DEB is not yet available. Experiments on DEB shape that aim to derive new coefficients in the parabolic bay shape equation (PBSE) for DEB are now being conducted in the laboratory. The work commences from an initial artificial HBB in static equilibrium with sediment supply source from the lee of an upcoast headland. A final equilibrium planform is obtained for the condition with a specific wave obliquity and sediment supply rate until no further shoreline change is found. In order to fit the PBSE for a DEB, a new parameter called SSR (sediment supply ratio) that represents the ratio of sediment supply rate from the source and the potential longshore sediment transport rate is introduced to quantify the balance of sediment to the bay. Alternative C coefficients in the PBSE for DEB, which include wave obliquity and the SSR, are then calculated. These new coefficients for DEB can now be used to evaluate the influence of sediment supply from a riverine source on a DEB and to classify its equilibrium status for planning sediment management strategies in coastal conservation. © 2016 Springer Science+Business Media Dordrecht Source

Meesuk V.,UNESCO-IHE Institute for Water Education | Meesuk V.,Hydro and Agro Informatics Institute | Vojinovic Z.,UNESCO-IHE Institute for Water Education | Mynett A.E.,UNESCO-IHE Institute for Water Education | And 2 more authors.
Advances in Water Resources | Year: 2015

Remote Sensing technologies are capable of providing high-resolution spatial data needed to set up advanced flood simulation models. Amongst them, aerial Light Detection and Ranging (LiDAR) surveys or Airborne Laser Scanner (ALS) systems have long been used to provide digital topographic maps. Nowadays, Remote Sensing data are commonly used to create Digital Terrain Models (DTMs) for detailed urban-flood modelling. However, the difficulty of relying on top-view LiDAR data only is that it cannot detect whether passages for floodwaters are hidden underneath vegetated areas or beneath overarching structures such as roads, railroads, and bridges. Such (hidden) small urban features can play an important role in urban flood propagation. In this paper, a complex urban area of Kuala Lumpur, Malaysia was chosen as a study area to simulate the extreme flooding event that occurred in 2003. Three different DTMs were generated and used as input for a two-dimensional (2D) urban flood model. A top-view LiDAR approach was used to create two DTMs: (i) a standard LiDAR-DTM and (ii) a Filtered LiDAR-DTM taking into account specific ground-view features. In addition, a Structure from Motion (SfM) approach was used to detect hidden urban features from a sequence of ground-view images; these ground-view SfM data were then combined with top-view Filtered LiDAR data to create (iii) a novel Multidimensional Fusion of Views-Digital Terrain Model (MFV-DTM). These DTMs were then used as a basis for the 2D urban flood model. The resulting dynamic flood maps are compared with observations at six measurement locations. It was found that when applying only top-view DTMs as input data, the flood simulation results appear to have mismatches in both floodwater depths and flood propagation patterns. In contrast, when employing the top-ground-view fusion approach (MFV-DTM), the results not only show a good agreement in floodwater depth, but also simulate more correctly the floodwater dynamics around small urban feature. Overall, the new multi-view approach of combining top-view LiDAR data with ground-view SfM observations shows a good potential for creating an accurate digital terrain map which can be then used as an input for a numerical urban flood model. © 2014 Elsevier Ltd. Source

Meesuk V.,Hydro and Agro Informatics Institute | Meesuk V.,UNESCO-IHE Institute for Water Education | Vojinovic Z.,UNESCO-IHE Institute for Water Education | Mynett A.E.,Technical University of Delft | Mynett A.E.,UNESCO-IHE Institute for Water Education
ICIAFS 2012 - Proceedings: 2012 IEEE 6th International Conference on Information and Automation for Sustainability | Year: 2012

Using physically based computational models coupled with remote sensing technologies, photogrammetry techniques, and GIS applications are important tools for flood hazard mapping and flood disaster prevention. Also, information processing of massive input data with refined accuracy allows us to develop and to improve urban-flood-modeling at a detailed level. The topographical information from digital surface model (DSM) or digital terrain model (DTM) is essential for flood managers who actually require this high accuracy and resolution of input data to set up their practical applications. Light detecting and ranging (LiDAR) techniques are mainly used, but these costly techniques can be appraised by equipments, maintenance, and operations which include aircraft. Recent advances in photogrammetry and computer vision technologies like structure form motion (SfM) technique are widely used and offer cost-effective approaches to reconstruct 3D-topographical information from simple 2D photos, so-called 3D reconstruction. In terms of input data for flood modeling, the SfM technique can be comparable to other acquisition-techniques. In this paper, there are one experimental and two case studies. Firstly, a result of the experiment showed a similarity between flood maps by applying the SfM process form the 3D-reconstruction and using benchmark information. These 3D-reconstruction processes started from 2D photos, which were taken from virtual scenes by using multidimensional-view approach. These photos can be used to generate 3D information which is later used to create the DSM from multidimensional fusion of views (MFV-DSM). Then, the DSM was used as input data to set up 2D flood modeling. Thereafter, when using the DSMs as topographical input data, comparison between a benchmark DSM and MFV-DSM shows similarity flood-map results in both flood depths and flood extends. Secondary, the two cases from real world scenes also showed possibilities of using the SfM technique as an alternative acquisition tool, providing 3D information. This information can be used as input data for setting up modeling and can possibly be comparable or even outcompete with other acquisition techniques, such as LiDAR. As a result, using the SfM technique can be extended to become promising methods in practicable applications for modeling real flood events in real world scenes. © 2012 IEEE. Source

Tantianuparp P.,Wuhan University | Tantianuparp P.,Hydro and Agro Informatics Institute | Balz T.,Wuhan University | Wang T.,Wuhan University | And 3 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012

Persistent Scatterer Interferometry (PS-InSAR) is applied to derive displacement information with millimetric precision. Analyzing stable persistent scatterers from a large stack of SAR images,helps to overcome the geometrical and temporal decorrelation, which occur when using differential interferometry. The removal of the topographic phase with an external DEM seems to cause problems. In our experiment, we select three different DEMs: ASTER GDEM, a DEM derived from a digitized topographic map, and SRTM-3 in order to analyze the influence of the input DEMs for PS-InSAR processing in the Three Gorges area. We find that differential interferogram generation is related to the topographic influence for the PS-InSAR processing and different DEMs get us different PS-InSAR results. © 2012 IEEE. Source

Tantianuparp P.,Wuhan University | Tantianuparp P.,Hydro and Agro Informatics Institute | Shi X.,Wuhan University | Liao M.,Wuhan University | And 2 more authors.
European Space Agency, (Special Publication) ESA SP | Year: 2013

Landslides are a major hazard in steep mountainous area, like the Three Gorges area. The Three Gorges dam was built on a geologically unstable zone. The geological pressures from the rising water level caused by the dam and the deforestation have further increased the possibility for landslides in the area. Many landslide monitoring techniques are applied to analysis, forecast, and control landslides in this area. D-InSAR and PS-InSAR, the time series InSAR analysis, are used for terrain motion detection and to estimate displacement trends. In this paper, SAR data from systems with different wavelengths, like the C-band ASAR, the L-band PALSAR, and the high-resolution TerraSAR-X X-band data, are used. Source

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