نتایج جستجو برای: levee
تعداد نتایج: 1247 فیلتر نتایج به سال:
[1] Levees are the primary elements of self-formed submarine channels, yet little is know about their morphodynamics. We present field observations of static levee morphology and stratigraphy in addition to laboratory experiments that link levee morphodynamics to turbidity current flow properties. These observations are used to motivate a levee growth model. Using a three-dimensional seismic vo...
More and more floods occurred over the last decade in France and in the world, causing important damages and significant costs. Moreover, levees are often not well maintained, so they hardly resist to major floods and can break easily. At French national scale, the length of levees, estimated to 7500 kilometers, and the lack of data all along these infrastructures complicates their management. ...
The utility of the multi-channel analysis of surface waves (MASW) seismic method for noninvasive assessment of earthen levees was evaluated for a section of the Citrus Lakefront Levee, New Orleans, Louisiana. This test was conducted after the New Orleans’ area levee system had been stressed by Hurricane Katrina in 2005. The MASW data were acquired in a seismically noisy, urban environment using...
We developed a robust approach for real-time levee condition monitoring based on combination of data-driven methods (one-side classification) and finite element analysis. It was implemented within a flood early warning system and validated on a series of full-scale levee failure experiments organised by the IJkdijk consortium in August-September 2012 in the Netherlands. Our approach has detecte...
a methodology of soil moisture assessment around a levee based on a backpropagation neural network and using Synthetic Aperture Radar (SAR) data is developed. Soil moisture changes along a levee over a period of time can help to monitor and find potential failure indicators such as slides and sand boils around the levee. Several analytical and empirical models have shown relationships between S...
Levee setback location and height are important issues in flood levee system design and modification. This paper derives an economic-engineering theory of the optimal trade-off of levee setback for height both for original and redesigned flood levees, demonstrating the interconnection of levee setback, height, costs and risks, and economically optimal design. These analyses assume stationary fl...
Present criteria for acceptable grass covered levee overtopping are based on average overtopping values but do not include the effect of overtopping duration. This paper applies experimental steady state results for acceptable overtopping to the case of intermittent wave overtopping. Laboratory results consisting of velocities and durations for acceptable land side levee erosion due to steady f...
The objective of the research was to provide a better understanding of the influence of hydraulic conductivity on the exit gradient for a rectangular block representing a root zone. A critical area of concern to design engineers is the exit gradient at the toe of the levee and other sensitive areas. If the exit gradient becomes too large, water flows too fast, thus creating the potential for pi...
The U.S. Army Corps of Engineers elevated Zoar Levee and Diversion Dam to a Dam Safety Action Class I (urgent and compelling) ranking due to seepage concerns. An accelerated program is in progress to address project deficiencies which include seepage through the levee’s glacial outwash foundation, through a fractured rock knoll beneath the levee, and through the dam’s fractured rock abutments a...
[1] Even in heavily engineered river systems, climate still governs flood variability and thus still drives many levee breaks and geomorphic changes. We assemble a 155-year record of levee breaks for a major California river system to find that breaks occurred in 25% of years during the 20th Century. A relation between levee breaks and river discharge is present that sets a discharge threshold ...
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