Landward limit of wind setup on beaches     

Todd L. Walton  Robert G. Dean 《Ocean Engineering》2009,36(9-10):763-766

Open coast storm surge water levels consist of a wind shear forcing component generally referred to as wind setup; a wave setup component caused by wind-induced waves transferring momentum to the water column; an atmospheric pressure head component due to the atmospheric pressure deficit over the spatial extent of the storm system; a Coriolis-forced component due to effects of the rotation of the earth acting on the wind-driven alongshore current at the coast; and, if astronomical tides are present, an astronomical tide component. Astronomical tide is considered to be predictable and, therefore, not a meteorological driven component of storm surge although there may be interaction between the tide and meteorological driven water levels. Typically the most important component of storm surge on the US East Coast and Gulf of Mexico shorelines is the wind setup component. The importance of inland flooding due to the wind setup component of storm surge is considered herein with special reference to the effect of subaerial slope on inland flooding where three different linear slopes are considered and storm surge is calculated for the region above still water level, using an analytic solution. The present study findings show that the inland storm surge from the wind setup component can be of considerable importance and lead to significantly higher storm surges than found for storm surge at the still water level intersection of the beach/land. It is shown that mild slopes can lead to very high water levels at the land–water interface (i.e. above the still water level intersection of the beach).  相似文献   

The abundance distributions of Galactic bulge and disc planetary nebulae     

K. M. Exter †  M. J. Barlow  N. A. Walton 《Monthly notices of the Royal Astronomical Society》2004,349(4):1291-1322

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Geochemistry of extremely alkaline (pH>12) ground water in slag-fill aquifers     

Roadcap GS  Kelly WR  Bethke CM 《Ground water》2005,43(6):806-816

Extremely alkaline ground water has been found underneath many shuttered steel mills and slag dumps and has been an impediment to the cleanup and economic redevelopment of these sites because little is known about the geochemistry. A large number of these sites occur in the Lake Calumet region of Chicago, Illinois, where large-scale infilling of the wetlands with steel slag has created an aquifer with pH values as high as 12.8. To understand the geochemistry of the alkaline ground water system, we analyzed samples of ground water and the associated slag and weathering products from four sites. We also considered several potential remediation schemes to lower the pH and toxicity of the water. The principal cause of the alkaline conditions is the weathering of calcium silicates within the slag. The resulting ground water at most of the sites is dominated by Ca2+ and OH- in equilibrium with Ca(OH)2. Where the alkaline ground water discharges in springs, atmospheric CO2 dissolves into the water and thick layers of calcite form. Iron, manganese, and other metals in the metallic portion of the slag have corroded to form more stable low-temperature oxides and sulfides and have not accumulated in large concentrations in the ground water. Calcite precipitated at the springs is rich in a number of heavy metals, suggesting that metals can move through the system as particulate matter. Air sparging appears to be an effective remediation strategy for reducing the toxicity of discharging alkaline water.  相似文献   

The Effective Elastic Moduli of Model Sediments     

K. Walton 《Geophysical Journal International》1975,43(2):293-306

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First Pressure Derivative of the Bulk Modulus for Porous Materials     

K. Walton 《Geophysical Journal International》1973,35(1-3):327-335

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Microtime Measurements of Ground-Water Level Fluctuations     

W. C. Walton Member NWWA 《Ground water》1963,1(2):18-19

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Infections and Inequalities     

Paul Farmer  David Walton  Laura Tarter 《Global Change & Human Health》2000,1(2):94-109

Anthrax. The word conjures images of germ warfare, which is pretty ridiculous when you discover that we're not really sure anthrax has ever been used in this fashion. Germ warfare is certainly not what came to mind when a six-year-old girl showed up in our clinic with half of her face puffed up like a balloon, her right eye swollen shut (Figure 1). We were in rural Haiti, where a very different sort of germ warfare is the rule. So what came to mind that day was the word epidemic, and sure enough a young woman from the same village was also diagnosed with cutaneous anthrax—called charbon in Haiti, "malignant pustule" in the older textbooks—on her right chest wall. Soon after their arrival, both were receiving intravenous penicillin; they would recover completely. Later that night, the clinic's medical staff held a meeting. Another anthrax case had been diagnosed a few days earlier, and the patient was from the same area. It seemed increasingly likely that we were dealing with an epidemic. By morning, we learned that a young man from the village had just died of charbon. Why? "Because he didn't have enough money to get here." It costs no more than four dollars to take a truck from their village to our clinic. It was an epidemic, all right, and it had already taken a life.  相似文献   

A Laboratory-Testing-Based Study on the Strength,Deformability, and Dilatancy of Carbonate Rocks at Low Confinement     

G. Walton  J. Arzúa  L. R. Alejano  M. S. Diederichs 《Rock Mechanics and Rock Engineering》2015,48(3):941-958

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Identification of probable groundwater paths in the Amargosa Desert vicinity     

Omar Al-Qudah  Arturo Woocay  John Walton 《Applied Geochemistry》2011,26(4):565-574

In this study, the hydrogeochemical program PHREEQC was used to determine the chemical speciation and mineral saturation indices (SIs) of groundwater in the vicinity of the proposed high-level nuclear waste repository at Yucca Mountain, Nevada (USA). In turn, these data were used to interpret the origin and recharge mode of groundwater, to elucidate the mechanisms of flow and transport, and to determine potential sources of groundwater contamination. PHREEQC was run to determine aqueous dissolved species and minerals that would be in equilibrium with the study area’s groundwater. Selected major ions, associated SI, F⁻ and Ca/Na ion exchange were then examined using the multivariate statistical methods of principal component factor analysis and k-means cluster analysis. Analysis of dissolved ion concentrations, SIs, and Ca/Na ion exchange allows simultaneous consideration of arithmetic (raw concentrations) and logarithmic (SI, ion exchange) variables that describe the hydrochemical system and, therefore, can provide further insight into the system’s behavior. The analysis indicates that the dominant processes and reactions responsible for the hydrochemical evolution in the system are (1) evaporative concentration prior to infiltration, (2) carbonate equilibrium, (3) silicate weathering reactions, (4) limited mixing with saline water, (5) dissolution/precipitation of calcite, dolomite and fluorite, and (6) ion exchange. Principal component factor analysis and k-means cluster analysis of factor scores allow the reduction of dimensions describing the system and the identification of hydrogeochemical facies and the processes that defined and govern their evolution.Statistical analysis results indicate that the northern, west face and southern Yucca Mountain groundwater is fresh water with low concentrations of Ca²⁺, Mg²⁺, Cl⁻, Ca²⁺/(Na⁺)², and CaF₂. The Fortymile Wash groundwater is dilute. The carbonate signature is shown in the Ash Meadows and Death Valley waters with high fluorite SI. Finally, the Crater Flat, Stripped Hills, and Skeleton Hills are dominated by Ca/Na ion exchange, Mg and Ca. The hydrochemical and statistical analyses showed three main groundwater signatures or hydrochemical processes indicating groundwater evolution, potential flowpaths, and recharge areas. The flowpaths are the trace of the Amargosa River, the trace of Fortymile Wash, and its convergence with the Amargosa River. This appears to represent not just a groundwater flow path, but traces of surface runoff infiltration as well.  相似文献   

Application of a water balance model to estimating hay growth in the peace river region     

C.H. Wallis  T.A. Black  O. Hertzman  V.J. Walton 《大气与海洋》2013,51(3):326-343

Abstract

A model that uses daily climate data for calculating hay crop growth in the Peace River region of British Columbia was developed and evaluated using data obtained over four growing seasons. The performances of the ratio of growth to transpiration and the ratio of growth to transpiration (J) divided by vapour pressure deficit (VPD) in estimating crop growth were compared. Transpiration was calculated by subtracting evaporation losses from the soil and foliage from the calculated evapotranspiration. Evapotranspiration was calculated using solar radiation and air temperature, and a one‐layer root zone water balance model, which accounted for soil water supply limitation. Soil water storage measurements showed that the water balance model worked well. The model provided satisfactory estimates of growing season yield of above‐ground dry matter. The use of the ratio of growth toT/ vpd showed no improvement in growth estimation over the ratio of growth to transpiration.  相似文献