Erosion problems are not only in the Texas area, but exist also along the coastline all over the world. Even though many researchers have studied coastal processes related with beach erosion and deposition over the decades, these processes are too complex to understand completely and field measurements are difficult to obtain during landfall of storms which cause fatal damages. Overwash is strongly suspected to cause extreme erosion as seen from long-term field measurements in the upper Texas coast. Overwash and washover are the source of cross-shore erosion and deposition of beach material along the coast, respectively. Waves superimposed on increased storm surges overtop and generate serious erosion of the berm. However, the data for these processes do not completely describe the shoreline erosion problems. Providing better descriptions requires field measurements and laboratory experiments with careful calibration. This study was conducted in two major sections. First was a field measurement and second was a laboratory experiment. This study used the RTK-DGPS to measure the change in the beach profile over multi year period. The GPS system is one of the ways to have the best resolution. The laboratory experiment was done in a 2D wave tank on mid-scale based on similitude law at Texas A&M University. The experiment was necessary to obtain better empirical formulas. The erosion rate of the sand was measured at different wave conditions and slopes of the berm or upper beach face in regular and irregular waves respectively. The erosion rate is much bigger at higher wave height, longer wave period and steeper beach face. The erosion rate is increased proportional to speed of bore and it is decreased with time. The empirical formulas were the first approach to simulate the impact of overwash. The laboratory results represented good agreement with the field data and might be applicable to predict the shoreline recession by overwash induced by storms. Further improvements can be expected by adding these empirical formulas to a numerical model to predict sediment transport in the swash zone.

This thesis presents a study made on erosion control blankets with respect to their aging and longevity. Erosion control blankets have been relied upon increasingly in recent times replacing the old and traditional methods for protecting areas from erosion by storm water and other factors. But what can be an estimated duration for which a given set of blankets can be functional in channel erosion control. This research is done with the ultimate aim of understanding whether these erosion control blankets can stay in place and be conducive to some vegetation growth, which is said to be the most reliable measure for long-lasting erosion control. Seven erosion control blankets, consisting of natural, synthetic and composite types, were put to actual use for erosion control for 3 years in a field. After 3 years these used materials were cut from the field for conducting the tests. Unused blankets of the same brands were obtained. Index tests were conducted on both used and unused material specimens to measure the erosion control properties. All materials experienced a significant amount of strength loss after use. The natural materials show 80% strength loss, while the composite and synthetic materials were tested to have around 50% strength losses after being put to use for 3 years. Thus it can be observed that the composite and synthetic materials have a decent amount of life where erosion control is concerned. Other tests also proved that composite materials can be relied upon for erosion control to a reasonable extent, and the research goal was achieved.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 81-83). Also available via World Wide Web.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2002. / Includes bibliographical references (leaves 37-39).

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A research program was undertaken to quantify the effect of flow induced erosion on the stability of natural river banks along the Red River in Winnipeg, Manitoba. The study correlated the percent decrease in factor of safety to intensity of river flow and duration. Two methods to quantify flow induced erosion were assessed, the first method based on observed erosion and the second on theoretically calculated erosion. The first method involved aligning annual historical river bank cross-sections and measuring the distance between cross-sections to represent the erosion induced from the flow year between successive cross-sections. Due to the fact there are no sites along the Red River regularly surveyed, the analysis did not provide for a correlation between erosion from a specific flow event to percent decrease in factor of safety. The second part involved the use of theoretical equations to quantify erosion given the river elevation of a specific flow year. The study showed a 1% to 8% decrease in factor of safety from low to high intensity flows and as high as 14.5% for high intensity flows of long duration. Additionally, the evolutionary stability of the riverbank was generated showing the percent decrease each year in factor of safety due to erosion and the years during which failure occurs. The results correlated well to the previous analysis showing a 1% to 5% decrease for low to high intensity flows respectively and as high as 10% for high intensities of long duration.

Motunau Beach is situated upon a small coastal promontory which is approximately 3 km in length. Around this promontory a complex of coastal processes are interacting. In the past there has been concern for people s property due to eroding sandstone cliffs. In response to the erosion hazard piecemeal structural solutions have been sought; however, due to their short longevity have proved inadequate. Based on regular shoreline profiling and observations in conjunction with a broad international literature base, the processes of wave refraction, cliff erosion, river mouth dynamics, and sand beach adjustment have been discussed. Sediment transport pathways have been inferred based upon the natural and human processes around the promontory and the morphological response since the 1950s. To analyse the coastal processes and morphological change at Motunau Beach a combination of qualitative and quantitative research methods have been used. The field study period of three months, July to September 2009, has focussed on the shortduration and high-frequency processes of change and nested within a broader context of coastal change since the 1950s. Initial results suggest that between the years 1950 to 1968 there was a loss of beach width on Sandy Bay of approximately 25 m. This was then followed by an increased rate of cliff erosion during the 1980s. Analysis of historical hindcast wave data since 1979 suggests the wave climate at Motunau is not distinctive from the rest of the east coast; however, the processes of wave refraction within the nearshore create a turbulent and dynamic nearshore wave environment which has implications on shoreline morphology. Results from this study indicate that nearshore sediment supplies are being exhausted by a increasing wave height of approximately 4 mm yr-1 since 1979. The turbulent wave environment of the nearshore zone at Motunau Beach is encouraging the offshore transfer of nearshore sediment supplies to a depth beyond the reworking of waves during swell condition. This has obvious implications for the long-term shoreline morphology at Motunau and shoreline protection from highintensity low frequency wave events.

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