Knowledge Core Collection:https://hdl.handle.net/11681/467392024-03-29T01:54:49Z2024-03-29T01:54:49ZThe inverse tsunami problem for symmetric islands of simple shapeKnowles, Charles ErnestReid, Robert O.https://hdl.handle.net/11681/243962023-04-04T13:58:35Z1970-06-01T00:00:00ZTitle: The inverse tsunami problem for symmetric islands of simple shape
Authors: Knowles, Charles Ernest; Reid, Robert O.
Abstract: Abstract: The problem investigated in this paper is that of estimating the deep water signature of a tsunami based on an observed marigram in the immediate vicinity of an
island. The basic assumption is made that the incident tsunami in deep water is represented by a plane wave but that its signature in time at a fixed point in deep water is unknown. This implies that the distance of the earthquake epicenter is large compared with the horizontal scale of the island at its base on the ocean floor. The present study is limited to the linear theory for long waves and accordingly its application requires that the observed water level signatures be at locations where non-linear effects and dispersion are minimal. The method is numerical. For a given direction of the input wave train in deep water and a given observation point (P) near the island, the solution of the problem as posed rest on the determination of the transfer function for the response at P due to the input. If the transfer function can be established from a known pair of input-output time sequences ·having a broad band spectrum, then presently being employed for the study of deep sea tides and could detect a tsunami (Miller, personal correspondence)), so what is known has been derived almost entirely from theory. Records obtained on small islands in the mid-Pacific have given the best information, but theoretical deductions imply that the waves can be significantly modified by the transformation that takes place when they interact with the island shoreline and surrounding sea-floor topography. Included in this interaction are modifications and amplifications due to linear and non-linear transformations related to shoaling, scattering, diffraction, refraction and possible resonance phenomena created when wave energy is trapped around the island by the bathymetry (see Longuet-Higgins, 1967). Studies of this transformation should take into account each of these factors.
Description: Contract Report1970-06-01T00:00:00ZFull Boltzmann discrete spectral wave model, implementation and nondimensional testsResio, Donald T.https://hdl.handle.net/11681/28012024-03-06T22:40:02Z1993-08-01T00:00:00ZTitle: Full Boltzmann discrete spectral wave model, implementation and nondimensional tests
Authors: Resio, Donald T.
Description: Contract report; Abstract: A full Boltzmann integration scheme is implemented within a functioning discrete spectral wave model. Preliminary testing (academic) is presented and compared to alternate solution methods. It is found that third-generation models depend on a detailed balance among source terms, and it is important that these source terms be specified accurately. In the present state of the art, information on all of the source terms does not appear to be sufficient to permit definitive estimates of all source terms in the detailed balance evaluations. Older means of estimating the nonlinear wave-wave interaction (Snl) are much less accurate than the full Boltzmann method. Even the Discrete Interaction Approximation (WAMDIG 1988) representation for Snl used in the only documented third-generation wave model (WAM) is shown incapable of providing an accurate estimate of Snl. The full Boltzmann model should provide an improved method to investigate several important wave generation and decay situations. The WAM source terms are inconsistent with observed wave-growth laws and equilibrium-range behavior from the Joint North Sea Wave Project (Hasseimann et al. 1973). New source terms postulated in this report provide a very good match to the JONSWAP wave growth rates and equilibrium-range behavior. The present version of the full Boltzmann model should be regarded as a research tool. It is a very new model and, as such, will need to undergo considerable additional testing over several years before it could be considered as a viable option for an operational model.1993-08-01T00:00:00ZShoreline and sediment volume changes at the Colorado River Mouth, TexasLiang, Guoxionghttps://hdl.handle.net/11681/28022024-03-13T19:54:45Z1995-08-01T00:00:00ZTitle: Shoreline and sediment volume changes at the Colorado River Mouth, Texas
Authors: Liang, Guoxiong
Description: Contract report; Abstract: Shoreline change at the Colorado River mouth, Texas, was estimated based on survey results from 1990 to 1992 and some historic data. In terms of the long-term variation, the shoreline in the north section is accretional. From 1984 to 1990, an area of 63,000 m2 was gained within the north section. On the other hand, some severe erosion can be caused by storms. Complex PCA was applied to analyze a fast-moving bar event. It showed significant advantages over the conventional PCA. Using fewer components, CPCA can explain more variations. The results of reconstruction by CPCA reflected the variation in the observed data set well. Volume changes in profiles were selected as variables for principal component analysis. Using the results, variation alongshore was detected. Further use of this method is expected to be fruitful.1995-08-01T00:00:00ZLongshore suspended sediment transport at the mouth of the Colorado River, Matagorda, TexasBeach, Reginald Andrew, 1958-https://hdl.handle.net/11681/28032024-03-22T13:13:13Z1995-12-01T00:00:00ZTitle: Longshore suspended sediment transport at the mouth of the Colorado River, Matagorda, Texas
Authors: Beach, Reginald Andrew, 1958-
Description: Contract report; Abstract: The primary objective of this investigation was to increase understanding of mean suspended sediment concentration longshore sediment transport rates in response to varying offshore wave conditions. Explicit objectives were as follows: (a) assist and advise in the deployment and collection of field data using optical suspended sensors during WES experiments at Colorado River, TX, (b) assist in the analysis and interpretation of such data, (c) use such data to evaluate the ability ( wave-current interaction sediment transport theory to calculate the observed suspended load and longshore flux of sediment (d) prepare and deploy fiber-optic suspended sediment sensors during WES experiments at Colorado River, TX, and (e) analyze data collected with the fiber-optic sensor. Addressing these objectives requires accurate measurement of the time-varying concentration field and fluid forcing.1995-12-01T00:00:00Z