The coupled effects of thermochemical and thermomechanical erosion are investigated. A quasi-steady ablation model with finite rate surface chemistry is developed and applied to a solid carbon combustion scenario to investigate the system’s behavior in situations in which surface reactions are not in equilibrium. It is found that in this regime, the system can be described effectively in terms of the B number and the Damkohler number, and a useful algebraic relationship between these parameters is determined for nonequilibrium behavior. The thermochemical ablation model is then expanded by considering mechanical removal of thermochemically weakened material from the ablating surface. A model is developed for a randomly oriented carbon fiber preform material, like that used in the production of phenolic impregnated carbon ablator (PICA), and this model is incorporated into the previously developed ablation code. It is found that for PICA in realistic reentry scenarios, the removal of individual fibers from the ablating surface by mechanical erosion is not an important mass loss mechanism, although hypothetical situations exist where this mechanism for mechanical removal of material is non-negligible. The thermo-chemo-mechanical erosion mechanism is then extended to address brand generation in wildland fire scenarios. A model is developed to predict the size and number distribution of embers generated from a tree with fractal geometry. This model is coupled to a simple plume and propagation model similar to those existing in the literature, and a case study is performed for a realistic wildfire scenario. The presence of an optimal branch diameter for brand propagation is identified, and areas for future work in thermo-chemo-mechanical degradation are discussed. / text

It is difficult to assess rangeland management practices at a hillslope scale because of the spatial and temporal variability of ecohydrological processes across a landscape. The Conservation Effects Assessment Project (CEAP) aims to provide a cost-effective method for quantifying benefits of conservation practices on rangelands. This study uses the Rangeland Hydrology and Erosion Model (RHEM) to develop a framework to assess rangeland management practices by quantifying sediment yield and runoff. Kaler Ranch, located in Eastern Arizona, was used as a study site because of their recently implemented rangeland conservation practices. Vegetation parameters were developed based on field data collected across the ranch and used to represent various rangeland management scenarios in RHEM. Peak flow and sediment yield rates were determined for each scenario using RHEM and were used as metrics to evaluate rangeland condition. RHEM provided an adequate method to evaluate the relative differences between upland rangeland management scenarios; however, it was less effective at evaluating changes in management practices within a riparian area.

On sandy coastlines dunes provide a barrier of protection from strong environmental forces that can naturally occur during storm events including storm surges that expose the dunes to large waves. A set of laboratory experiments were used to investigate the morphological processes during the erosion of a steep dune face under bichromatic wave conditions for two different mean water level elevations, corresponding to storm surges and waves that collide with or overwash the dune. In the collision regime, episodic slumping due to the undercutting of the dune resulted in sudden erosional events followed by long periods of wave-driven reshaping at the dune toe. In the overwash regime, dune erosion was faster and occurred at a more consistent rate. Small scale bedforms (ripples) measured during the overwash test evolved in height faster and to greater overall heights than collision test while bedform lengths were not affected by the change in water level. A numerical model, XBeach, was calibrated to examine the ability to predict erosion of the steep dune due to waves in the two water level regimes. XBeach was not able to recreate the spatial variability of the significant wave height profile from the laboratory measurements; however, mean velocities were in good agreement with observations suggesting that bed shear stress is well estimated. During mobile bed simulations of erosion in the two regimes, the model was in agreement with measured dune erosion after initial adjustment. XBeach was very sensitive to several parameters that control the rate of erosion including the critical avalanching slope under water, the threshold water depth and the sediment transport formulation. The model did not perform well at predicting erosion rates until these parameters had been modified. Overall, XBeach performed better when simulating dune erosion in the overwash regime than the collision regime. / Thesis (Master, Civil Engineering) -- Queen's University, 2014-04-01 14:54:35.257

Mit dem Kartoffelanbau in Hanglagen sind erhebliche Erosionsgefahren verbunden. Insbesondere die Dammformung, das Absieben und der späte Bestandsschluss sind dafür verantwortlich. Zur Beurteilung der Erosionsgefährdung von Kartoffelflächen wurde ein Zusatzmodul für das Modell Erosion-3D entwickelt. Mit diesem Modul lassen sich besonders gefährdete Flächen identifizieren sowie Schutzmaßnahmen wie Hanglängenverkürzung durch Grünstreifen, Schlagteilung und Richtungsänderung der Kartoffeldämme vorab in ihrer Wirksamkeit bewerten. Der Bericht erläutert die Funktionsweise des Zusatzmoduls und seine beispielhafte Anwendung in Praxisbetrieben.

Soil erosion has been recognised as a global threat against the sustainability of natural ecosystem. The work in this thesis has been undertaken to assist in combating this threat, and addresses the soil erosion issues associated with urban construction activities. The Revised Universal Soil Loss Equation (RUSLE) was employed in this research work and the parameters associated with the model were calibrated. This model was chosen for calibration, as it has been proven to be an easy to use tool yet providing reasonable results. Large scale rainfall simulators developed at UWS were used for rainfall simulation at two sites with diverse soil types: dispersive clayey soils at Penrith and highly permeable sandy soil at Somersby (Both in New South Wales, Australia). It is concluded that RUSLE can be successfully used in single storms for erosion prediction. Calibrated values of RUSLE parameters are useful in predicting soil erosion from the construction sites in NSW. It is also identified that in rolled smooth land condition, clayey soils are more erodible than sandy soil. Specific support practices such as short grass strips, gravel bags and silt fences are identified as very effective erosion control measures in reducing soil erosion from 45% to 85%. These results will be very useful in soil erosion prediction planning and conservation management in NSW. / Master of Engineering (Hons)

Thesis (doctoral)--Université de Rennes, 2004. / Includes bibliographical references (p. 197-209). Also available on the World Wide Web.

Thesis (Ph. D.)--University of California, Santa Cruz, 2002. / Typescript. Includes bibliographical references (leaves 126-133).

Thesis (Ph. D.)--University of California, Santa Cruz, 1998. / Typescript. Includes bibliographical references.

Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Kevin A. Haas; Committee Member: Emanuele Di Lorenzo; Committee Member: Hermann M. Fritz; Committee Member: Paul A. Work; Committee Member: Terry W. Sturm. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2003. / Includes vita. Includes bibliographical references (leaves 274-286).