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J. Nicholson I. Broker J. A. Roelvink D. Price J. M. Tanguy L. Moreno 《Coastal Engineering》1997,31(1-4)
Five different coastal area morphodynamic models have been set up to run on the same offshore breakwater layout and an intercomparison carried out on the hydrodynamic and morphodynamic output produced by each scheme. In addition, the predicted morphodynamics was checked against available laboratory and field data.It is concluded that the models are capable of producing realistic estimates for the dominant morphodynamic features associated with offshore breakwaters. Coupling of the wave, current and sediment transport components of each scheme is shown to yield bathymetry which attains a state of equilibrium, unlike models which are based on the initial transport field only. 相似文献
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This paper describes the results of an experimental investigation of the microwave backscatter from several laboratory generated transient breaking waves. The breaking waves were generated mechanically in a 35 m×0.7 m×1.14 m deep wave tank, utilizing chirped wave packets spanning the frequency range 0.8-2.0 Hz. Backscatter measurements, were taken by a X/K-band (10.525 GHz, 24.125 GHz) continuous wave Doppler radar at 30°, 45°, and 60° angles of incidence, and at azimuth angles of 0° and 180° relative to the direction of wave propagation. Surface profiles were measured with a high-speed video camera and laser sheet technique. Specular facets were detected by imaging the surface from the perspective of the radar. The maximum radar backscatter occurred in the upwave direction prior to wave breaking, was nearly polarization independent and corresponded to the detection of specular facets on the steepened wave face. This peak radar backscatter was predicted through a finite conductivity corrected physical optics technique over the measured surface wave profiles. Post break backscatter was predicted using a roughness corrected physical optics technique and the small perturbation method, which was found to predict the returns for vertical polarization, but to under predict the horizontal returns 相似文献
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Abdul-Lateef Balogun Abdul-Nasir Matori Adekunle Isa Hamid-Mosaku Dano Umar Lawal Imtiaz Ahmed Chandio 《Marine Georesources & Geotechnology》2017,35(7):961-969
Proper pipeline route selection is an integral component of a typical oil exploration and transportation project. Improperly selected routes could have severe consequences including pipe failures, oil spillage, and environmental disasters. Consequently, technologies like geographic information systems (GIS) are increasingly being used to facilitate the oil pipeline route selection procedure—especially for onshore routing projects. Surprisingly, not much has been documented on the application of GIS to offshore pipeline routing. With recent discoveries on the merits of offshore oil exploration, it is necessary to extend the analytical capabilities of GIS to the unique offshore domain. However, concerns have been raised regarding the limitations of GIS in accurately prioritizing diverse selection criteria in typical multi-criteria decision-making (MCDM) problems like route selection. Consequently, this paper addresses the offshore/subsea pipeline routing constraint using a hybrid decision support system (DSS), which integrates a GIS and fuzzy logic-based approximate reasoning (AR) models for optimal performance. The resultant spatial decision support system (SDSS) was successfully applied to a case study in Malaysia. The AR algorithm calculated the significance level of the multiple criteria using various fuzzy linguistic variables and membership functions. The aggregated priority ranking from different pipeline routing experts showed that the overall influence of the environmental criteria (61.4%) significantly exceeded that of other equally important criteria in the study area. These rankings were inputted into the SDSS to simulate various probable routes. Final results accurately highlighted an optimal route, which places a premium on the protection of environmental features in the subsea study area—in alignment with the preferences of majority of the experts. 相似文献
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Imtiaz Ahmed Chandio Abd Nasir B. Matori Khamaruzaman B. WanYusof Mir Aftab Hussain Talpur Abdul-Lateef Balogun Dano Umar Lawal 《Arabian Journal of Geosciences》2013,6(8):3059-3066
Information and communication technology, which has been incorporated and provided in the Geographic Information System (GIS), is valuable and effective geospatial information for the decision makers in improving their decisions in planning and development. The integration of this GIS using the multicriteria decision analysis approach provides an environment to the decision makers in citing areas using land suitability analysis procedures. This review paper particularly examines the GIS-based analytic hierarchy process as a multicriteria analysis/evaluation technique in land suitability analysis by means of literature reviews and surveys. 相似文献
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In order to improve understanding of the fate of septic tank or individual sewage disposal system (ISDS) effluent in regolith overlying fractured-rock aquifers, effluent from an ISDS in such a setting was tracked via geophysical, hydrological, and geochemical methods. Under typical precipitation conditions, the effluent entered the fractured bedrock within 5 m of the boundary of the constructed infiltration area. During a period of unusually high spring recharge, the plume migrated between 50 and 100 m within the regolith before infiltrating the fractured bedrock. The chemical signature of the effluent is similar to that required to account for the decline in water quality, suggesting a causative relationship (as estimated from mass-balance models of the surface-water chemistry near the mouth of the basin). The elevated salt content of the effluent during periods of high natural recharge to the infiltration area correlates with elevated salt concentrations in surface and groundwater at the basin scale, suggesting that some of the effluent salt load may be stored in the unsaturated zone during dry periods and flushed during periods of elevated natural recharge. 相似文献
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The performance of the new wave diffraction feature of the shallow-water spectral model SWAN, particularly its ability to predict the multidirectional wave transformation around shore-parallel emerged breakwaters is examined using laboratory and field data. Comparison between model predictions and field measurements of directional spectra was used to identify the importance of various wave transformation processes in the evolution of the directional wave field. First, the model was evaluated against laboratory measurements of diffracted multidirectional waves around a breakwater shoulder. Excellent agreement between the model predictions and measurements was found for broad frequency and directional spectra. The performance of the model worsened with decreasing frequency and directional spread. Next, the performance of the model with regard to diffraction–refraction was assessed for directional wave spectra around detached breakwaters. Seven different field cases were considered: three wind–sea spectra with broad frequency and directional distributions, each coming from a different direction; two swell–sea bimodal spectra; and two swell spectra with narrow frequency and directional distributions. The new diffraction functionality in SWAN improved the prediction of wave heights around shore-parallel breakwaters. Processes such as beach reflection and wave transmission through breakwaters seem to have a significant role on transformation of swell waves behind the breakwaters. Bottom friction and wave–current interactions were less important, while the difference in frequency and directional distribution might be associated with seiching. 相似文献
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Tidal channels and inlets in alluvial environments are interconnected dynamic systems that react to changing physical conditions (such as sea level rise) as well as to anthropogenic impact (such as dredging and bank protection works). Past research resulted in an empirical equilibrium relationship for inlets between the tidal prism (P) and the cross-sectional area in a tidal inlet (A). Constant PA relationships were found along several tidal basins. 相似文献
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This paper discusses the quality of the procedure employed in identifying soil parameters by inverse analysis. This procedure includes a FEM‐simulation for which two constitutive models—a linear elastic perfectly plastic Mohr–Coulomb model and a strain‐hardening elasto‐plastic model—are successively considered. Two kinds of optimization algorithms have been used: a deterministic simplex method and a stochastic genetic method. The soil data come from the results of two pressuremeter tests, complemented by triaxial and resonant column testing. First, the inverse analysis has been performed separately on each pressuremeter test. The genetic method presents the advantage of providing a collection of satisfactory solutions, among which a geotechnical engineer has to choose the optimal one based on his scientific background and/or additional analyses based on further experimental test results. This advantage is enhanced when all the constitutive parameters sensitive to the considered problem have to be identified without restrictions in the search space. Second, the experimental values of the two pressuremeter tests have been processed simultaneously, so that the inverse analysis becomes a multi‐objective optimization problem. The genetic method allows the user to choose the most suitable parameter set according to the Pareto frontier and to guarantee the coherence between the tests. The sets of optimized parameters obtained from inverse analyses are then used to calculate the response of a spread footing, which is part of a predictive benchmark. The numerical results with respect to both the constitutive models and the inverse analysis procedure are discussed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献