Results 1 - 10
of
501
The soil and water assessment tool—Historical development applications, and future research directions
- Transactions of the American Society of Agricultural and Biological Engineers
, 2007
"... An updated version of the paper will be published in a forthcoming Transactions of the ASABE. Questions or comments about the contents of this paper should be directed to Philip W. Gassman, ..."
Abstract
-
Cited by 92 (4 self)
- Add to MetaCart
(Show Context)
An updated version of the paper will be published in a forthcoming Transactions of the ASABE. Questions or comments about the contents of this paper should be directed to Philip W. Gassman,
MT3DMS: A modular three-dimensional multi-species transport model for simulation of advection, dispersion, and chemical reactions of contaminants in ground-water systems. Documentation and user's guide
- Contract Report SERDP-99-1, U.S. Army Engineer Research and Development
, 1999
"... PRINTED ON RECYCLED PAPER The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed ..."
Abstract
-
Cited by 76 (5 self)
- Add to MetaCart
PRINTED ON RECYCLED PAPER The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.
Algorithm 856: APPSPACK 4.0: Asynchronous parallel pattern search for derivative-free optimization
- ACM T. Math. Software
"... APPSPACK is software for solving unconstrained and bound-constrained optimization problems. It implements an asynchronous parallel pattern search method that has been specifically designed for problems characterized by expensive function evaluations. Using APPSPACK to solve optimization problems has ..."
Abstract
-
Cited by 35 (7 self)
- Add to MetaCart
APPSPACK is software for solving unconstrained and bound-constrained optimization problems. It implements an asynchronous parallel pattern search method that has been specifically designed for problems characterized by expensive function evaluations. Using APPSPACK to solve optimization problems has several advantages: No derivative information is needed; the procedure for evaluating the objective function can be executed via a separate program or script; the code can be run serially or in parallel, regardless of whether the function evaluation itself is parallel; and the software is freely available. We describe the underlying algorithm, data structures, and features of APPSPACK version 4.0, as well as how to use and customize the software.
Geological Survey
- Van Dijk PM, Kuenzer C Zhang J, Wolf KHAA and Wang J
, 2010
"... Y u ca ipa Ba sin ..."
(Show Context)
Groundwater availability of the Trinity Aquifer, Hill Country Area, Texas: numerical simulations through 2050: Texas Water Development Board Report 353
, 2000
"... by ..."
(Show Context)
Extinction depth and evapotranspiration from ground water under selected land covers
- Ground Water
, 2007
"... In many landscapes, vegetation extracts water from both the unsaturated and the saturated zones. The parti-tioning of evapotranspiration (ET) into vadose zone evapotranspiration and ground water evapotranspiration (GWET) is complex because it depends on land cover and subsurface characteristics. Tra ..."
Abstract
-
Cited by 11 (0 self)
- Add to MetaCart
(Show Context)
In many landscapes, vegetation extracts water from both the unsaturated and the saturated zones. The parti-tioning of evapotranspiration (ET) into vadose zone evapotranspiration and ground water evapotranspiration (GWET) is complex because it depends on land cover and subsurface characteristics. Traditionally, the GWET fraction is assumed to decay with increasing depth to the water table (DTWT), attaining a value of 0 at what is termed the extinction depth. A simple assumption of linear decay with depth is often used but has never been rig-orously examined using unsaturated-saturated flow simulations. Furthermore, it is not well understood how to relate extinction depths to characteristics of land cover and soil texture. In this work, variable saturation flow the-ory is used to simulate GWET for three land covers and a range of soil properties under drying soil conditions. For a water table within half a meter of the land surface, nearly all ET is extracted from ground water due to the close hydraulic connection between the unsaturated and the saturated zones. For deep-rooted vegetation, the decoupling of ground water and vadose zone was found to begin at water table depths between 30 and 100 cm, depending on the soil texture. The decline of ET with DTWT is better simulated by an exponential decay function than the commonly used linear decay. A comparison with field data is consistent with the findings of this study. Tables are provided to vary the extinction depth for heterogeneous landscapes with different vegetation cover and soil properties.
Preliminary Watershed Hydrology Model for Reclaimed Oil Sands Sites
- http://hdl.handle.net/10402/era.37308 Oil Sands Research and Information Network, 2013. Future of Shrubs in Oil Sands Reclamation Workshop
, 2013
"... organization that compiles, interprets and analyses available knowledge about managing the environmental impacts to landscapes and water impacted by oil sands mining and gets that knowledge into the hands of those who can use it to drive breakthrough improvements in regulations and practices. OSRIN ..."
Abstract
-
Cited by 10 (0 self)
- Add to MetaCart
(Show Context)
organization that compiles, interprets and analyses available knowledge about managing the environmental impacts to landscapes and water impacted by oil sands mining and gets that knowledge into the hands of those who can use it to drive breakthrough improvements in regulations and practices. OSRIN is a project of the University of Alberta’s School of Energy and the Environment (SEE). OSRIN was launched with a start-up grant of $4.5 million from Alberta Environment and a $250,000 grant from the Canada School of Energy and Environment Ltd. OSRIN provides: Governments with the independent, objective, and credible information and analysis required to put appropriate regulatory and policy frameworks in place Media, opinion leaders and the general public with the facts about oil sands development, its environmental and social impacts, and landscape/water reclamation activities – so that public dialogue and policy is informed by solid evidence Industry with ready access to an integrated view of research that will help them make and execute environmental management plans – a view that crosses disciplines
Transport of Conservative Solutes in Simulated Fracture Networks 2. Ensemble Solute Transport and the Correspondence to OperatorStable Limit Distributions
- Water Resources Research
"... [1] This paper investigates whether particle ensembles in a fractured rock domain may be adequately modeled as an operator-stable plume. If this statistical model applies to transport in fractured media, then an ensemble plume in a fractured rock domain may be modeled using the novel Fokker-Planck ..."
Abstract
-
Cited by 10 (4 self)
- Add to MetaCart
(Show Context)
[1] This paper investigates whether particle ensembles in a fractured rock domain may be adequately modeled as an operator-stable plume. If this statistical model applies to transport in fractured media, then an ensemble plume in a fractured rock domain may be modeled using the novel Fokker-Planck evolution equation of the operator-stable plume. These plumes (which include the classical multi-Gaussian as a subset) are typically characterized by power law leading-edge concentration profiles and super-Fickian growth rates. To investigate the possible correspondence of ensemble plumes to operator-stable densities, we use numerical simulations of fluid flow and solute transport through largescale (2.5 km by 2.5 km), randomly generated fracture networks. These two-dimensional networks are generated according to fracture statistics obtained from field studies that describe fracture length, transmissivity, density, and orientation. A fracture continuum approach using MODFLOW is developed for the solution of fluid flow within the fracture network and low-permeability rock matrix, while a particle-tracking code, random walk particle method for simulating transport in heterogeneous permeable media (RWHet), is used to simulate the advective motion of conservative solutes through the model domain. By deterministically mapping individual fractures onto a highly discretized finite difference grid (1 m  1 m  1 m here), the MODFLOW ''continuum'' simulations can faithfully preserve details of the generated network and can approximate fluid flow in a discrete fracture network model. An advantage of the MODFLOW approach is that matrix permeability can be made nonzero to account for any degree of matrix flow and/or transport.
Numerical simulation of tracer tests in heterogeneous aquifer
- J. Environ. Eng. 124 Ž
, 1998
"... ABSTRACT: A large-scale, natural-gradient tracer test in a heterogeneous aquifer at a site near Columbus, Miss. is simulated using three-dimensional (3D) hydraulic conductivity distributions derived from the borehole flowmeter test data. The simulated plume is more sensitive to the way the hydraulic ..."
Abstract
-
Cited by 9 (1 self)
- Add to MetaCart
(Show Context)
ABSTRACT: A large-scale, natural-gradient tracer test in a heterogeneous aquifer at a site near Columbus, Miss. is simulated using three-dimensional (3D) hydraulic conductivity distributions derived from the borehole flowmeter test data. The simulated plume is more sensitive to the way the hydraulic conductivity field is interpolated from the measured data than it is to the dispersivity value. The transport model with longitudinal dispersivities in the range of 1-5 m can reasonably reproduce the observed plume to a certain concentration limit, but fails to reproduce the significant spreading of the tracer at diluted concentrations as observed in the field. This modeling study illustrates the formidable challenges in modeling and monitoring contaminant transport in very heterogeneous aquifers and points to the needs for new, innovative monitoring techniques that can be applied to characterize the spatial and temporal variabilities in the aquifer properties at scales suitable for detailed transport modeling.
