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Earth Sciences

Selected Works

Articles 1 - 9 of 9

Full-Text Articles in Other Civil and Environmental Engineering

Climate Change And Hydrological Risks Related To Railway Infrastructure In Northern Regions, Barry A. Palynchuk Phd Oct 2013

Climate Change And Hydrological Risks Related To Railway Infrastructure In Northern Regions, Barry A. Palynchuk Phd

Barry A. Palynchuk PhD

In this paper, the authors discuss the possible consequences of global warming on northern hydrology and their impacts on railway drainage infrastructure. How can we change actual design approaches, methods and standards to adapt, to reduce vulnerability and to improve resilience to climate change? Under current climate conditions, snow, ice and permafrost play a dominant role in the water balance in cold regions. Three areas can be distinguished: regions of continuous permafrost, regions of discontinuous permafrost and permafrost-free regions. To predict the potential climate change impacts on each region, the spatial analog and the climate variability analog approaches can be …

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Evaluation Of Beach Nourishment Evolution Models Using Data From Two South Carolina Beaches: Folly Beach And Hunting Island, Sc, Usa, Harry Weathers, George Voulgaris Dec 2012

Evaluation Of Beach Nourishment Evolution Models Using Data From Two South Carolina Beaches: Folly Beach And Hunting Island, Sc, Usa, Harry Weathers, George Voulgaris

George Voulgaris

Beach nourishment is a common method used for mitigating coastal erosion. However, it is also a costly undertaking and requires an appropriate cost-to-benefit analysis. Although the costs can be estimated relatively easily, the benefits are directly related to the life expectancy of the proposed project. With this in mind, three existing beach replenishment time-evolution models (the Linear Erosion, the Verhagen, and the One-Line models) were compared for their ability to represent data from two beach nourishment projects that have taken place in South Carolina, USA, at Folly Beach and Hunting Island. Another newly introduced model that combines the One-Line model …

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First-Order Catchment Mass Balance During The Wet Season In The Panama Canal Watershed, Fred Ogden Aug 2012

First-Order Catchment Mass Balance During The Wet Season In The Panama Canal Watershed, Fred Ogden

Fred L. Ogden

Tropical hydrology is poorly understood for a number of reasons. Intense biological activity in the tropics introduces complexities to the hydrologic process. Bioturbation, rapid rates of decay, and intensive insect activity all tend to promote rapid flow paths in the upper soil. Aggressive weathering leads to clays depleted of light cations and deep soil profiles. Processes in the seasonal tropics are further complicated by seasonal transitions, and very large changes in catchment storage between seasons. Beginning in 2005, we installed a suite of hydrologic sensors in a 16.7 ha first-order catchment in the Panama Canal Watershed to observe hydrologic variables …

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Reverse Logic - Safety Of Spent Nuclear Fuel Disposal, Antti Lempinen, Marianne Silvan-Lempinen Dec 2010

Reverse Logic - Safety Of Spent Nuclear Fuel Disposal, Antti Lempinen, Marianne Silvan-Lempinen

Antti Lempinen

No abstract provided.

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A Method For Computing Infiltration And Redistribution In A Discretized Moisture Content Domain, Fred L. Ogden Jul 2008

A Method For Computing Infiltration And Redistribution In A Discretized Moisture Content Domain, Fred L. Ogden

Fred L. Ogden

A new one-dimensional infiltration and redistribution method is proposed as an alternative to the Richards equation (RE) for coupled surface and subsurface models. The proposed method discretizes soil water content into hypothetical hydraulically interacting bins. The entry and propagation of displacement fronts in each bin are simulated by means of explicit infiltration and drainage approximations based on capillary and gravitational driving forces. Wetting front advances within bins create water deficits that are satisfied by capillary-driven interbin flow. The method inherently provides numerical stability by precluding the need to directly estimate nonlinear gradients through numerical schemes. Comparisons of the performance of …

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Digital Elevation Accuracy And Grid Cell Size: Effects On Computed Topographic Attributes, Rob H. Erskine, Timothy R. Green Dec 2006

Digital Elevation Accuracy And Grid Cell Size: Effects On Computed Topographic Attributes, Rob H. Erskine, Timothy R. Green

Timothy R. Green

Terrain attributes are commonly used to explain the spatial variability of agronomic, pedologic, and hydrologic variables. The terrain attributes studied here (elevation, slope, aspect, and curvature) are estimated readily from digital elevation models (DEMs), but questions remain about how the accuracy and sample spacing of the elevation data affect the estimated attributes. The main objective of this study was to quantify differences in each terrain attribute due to factors affecting DEM accuracy and grid cell size. Three data sources were compared: (i) real-time kinematic global positioning system (RTKGPS); (ii) satellite-differentially corrected global positioning system (DGPS); and (iii) U.S. Geological Survey …

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Runoff Production In The Upper Rio Chagres Watershed, Panama, Fred Ogden Dec 2004

Runoff Production In The Upper Rio Chagres Watershed, Panama, Fred Ogden

Fred L. Ogden

Runoff production in tropical watersheds is governed by a wide variety of potential sources and there have been few rigorous studies to date. The 414 km2 upper Río Chagres basin offers a unique opportunity to better understand the runoff production mechanisms in tropical watersheds through data analysis and modeling with rainfall and runoff data. Flow data and tipping bucket rain gage data are available at both the basin outlet (Chico gage) and for an 80.6 km2 internal basin location (Piedras gage). Modeling is performed using the Sacramento Soil Moisture Accounting Model (SAC-SMA), calibrated using data from 2000 and verified using …

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Numerical Investigation Of Saturated Source Area Behavior At The Small Catchment Scale, Fred L. Ogden Dec 2003

Numerical Investigation Of Saturated Source Area Behavior At The Small Catchment Scale, Fred L. Ogden

Fred L. Ogden

The objective of this research is to explore the relationship between small catchment properties and the temporal growth and decay of saturated source areas (SSA). A simple physics-based hydrologic model, which we call the Sandbox model, is developed for this purpose. A thorough sensitivity analysis is undertaken to evaluate model response to variations in model parameters. Sandbox model output is compared to that from the semi-distributed conceptual model, TOPMODEL, a model with a wide spread acceptance. Plotting the temporal evolution of the extent of saturated source area versus catchment average soil water content dur- ing a number of wetting and …

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Green And Ampt Infiltration With Redistribution, Fred L. Ogden Aug 1997

Green And Ampt Infiltration With Redistribution, Fred L. Ogden

Fred L. Ogden

Distributed, physically based watershed and irrigation advance models require robust infiltration estimation capabilities. The empirical Green and Ampt (GA) equation of infiltration is a popular method for estimating infiltration. The GA parameters have physical basis and considerable prior research has focused on relating these parameters to soil textural classification. However, the original GA method is limited in that it is applicable only for a single ponding period. An explicit Green and Ampt redistribution (GAR) technique is developed herein to estimate interstorm redistribution of soil water and allow multiple ponding simulations using the GA methodology. Soil water redistribution during interponding periods …

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