نتایج جستجو برای: aquifers

تعداد نتایج: 4722  

Journal: :Ground water 2013
William C Walton Charles F McLane

Introduction Groundwater supply sustainable yield is herein defined as how much water can be withdrawn from an aquifer system, where and for how long, with acceptable physical, economical, environmental, social, cultural, institutional, and legal consequences. The purpose of this Technical Commentary is to focus on the following technical aspects of groundwater supply sustainable yield that are...

2003
Ian C. Jones Jay L. Banner

The hydrology and geochemistry of groundwater in tropical island aquifers, such as Barbados, Guam and Puerto Rico, are significantly influenced by tropical climatic conditions. Recharge to these aquifers is the product of regional and local climate patterns that control rainfall. Oxygen isotopes can be used to estimate the amount and timing of recharge on these islands because seasonal fluctuat...

2003
N. Dörfliger

ABSTRACT The French Mediterranean coastal aquifers are essentially alluvial, deep sedimentary and karst. Whereas the alluvial aquifers are particularly sensitive to salt-water intru sion, contamination of the deep aquifers is generally due to vertical hydraulic connec tion with the shallow aquifers. As for the karst systems, which are quite well developed f rom Languedoc-Roussillon to Provence-...

2017
Yu-Pin Lin Yu-Wen Chen Liang-Cheng Chang Ming-Sheng Yeh Guo-Hao Huang Joy R. Petway

This study presents an approach for obtaining limited sets of realizations of hydraulic conductivity (K) of multiple aquifers using simulated annealing (SA) simulation and spatial correlations among aquifers to simulate realizations of hydraulic heads and quantify their uncertainty in the Pingtung Plain, Taiwan. The proposed approach used the SA algorithm to generate large sets of natural logar...

2007
Jaya Kumar Gurung Hiroaki Ishiga Mohan Singh Khadka Raj Shrestha

The groundwater is an important source of drinking water in the Kathmandu Valley, and is presently fulfilling about forty five percent of the total demand of water supply. However, the deteriorating groundwater quality is an emerging issue of concern. In this study attempt has been done to characterize the groundwater for the fate of arsenic and nitrate contaminations. Physico-chemical paramete...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2011
Lenny H E Winkel Thi Kim Trang Pham Mai Lan Vi Caroline Stengel Manouchehr Amini Thi Ha Nguyen Hung Viet Pham Michael Berg

Arsenic contamination of shallow groundwater is among the biggest health threats in the developing world. Targeting uncontaminated deep aquifers is a popular mitigation option although its long-term impact remains unknown. Here we present the alarming results of a large-scale groundwater survey covering the entire Red River Delta and a unique probability model based on three-dimensional Quatern...

2007
Hassan Hassanzadeh Mehran Pooladi-Darvish

CO2 storage in deep saline aquifers is considered a possible option for mitigation of greenhouse gas emissions from anthropogenic sources. Understanding of the underlying mechanisms, such as convective mixing, that affect the long-term fate of the injected CO2 in deep saline aquifers, is of prime importance. We present scaling analysis of the convective mixing of CO2 in saline aquifers based on...

2012
Remko Leijs Egbert H. van Nes Chris H. Watts Steven J. B. Cooper William F. Humphreys Katja Hogendoorn

Evidence is growing that not only allopatric but also sympatric speciation can be important in the evolution of species. Sympatric speciation has most convincingly been demonstrated in laboratory experiments with bacteria, but field-based evidence is limited to a few cases. The recently discovered plethora of subterranean diving beetle species in isolated aquifers in the arid interior of Austra...

Journal: :Ground water 2005
Danelle D Clarke Mark M Meerschaert Stephen W Wheatcraft

Alternative fractional models of contaminant transport lead to a new travel time formula for arbitrary concentration levels. For an evolving contaminant plume in a highly heterogeneous aquifer, the new formula predicts much earlier arrival at low concentrations. Travel times of contaminant fronts and plumes are often obtained from Darcy's law calculations using estimates of average pore velocit...

2007
David Love Wouter de Hamer Richard J.S. Owen Martijn Booij Stefan Uhlenbrook Arjen Y. Hoekstra Pieter van der Zaag

An alluvial aquifer can be described as a groundwater system, generally unconfined, that is hosted in laterally discontinuous layers of gravel, sand, silt and clay, deposited by a river in a river channel, banks or flood plain. In semi-arid regions, streams that are associated with alluvial aquifers tend to vary from discharge water bodies in the dry season, to recharge water bodies during cert...

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