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In 1989, the Southern Nevada Water Authority (SNWA) launched the Southern Nevada Groundwater Development Project—a bold plan to construct a series of deep wells in east‐central Nevada to pump groundwater and send it to the Las Vegas region through 300 miles of pipeline. Before starting work on the project, SNWA conducted an environmental impact study and secured water rights in the valleys. Applications for additional new water rights were filed with Nevada State Engineer on the basis of uncaptured evapotranspiration. The SNWA spent decades and millions of dollars studying the hydrogeology of the region and developing computer models to demonstrate that the project would not have an unduly negative impact on the ecology or water users in the region. The project was opposed by environmental groups, native American tribes, and existing water rights holders. One of the protestants was the Cleveland Ranch in Spring Valley. Using the SNWA's own groundwater model, the ranch argued that the project would result in substantial harm to the ranch's water rights which included springs, wells, and a stream, and that the project would result in perpetual groundwater mining, which is forbidden by Nevada state policy. The Nevada State Engineer approved the project, but the decision was eventually reversed by Seventh District Court, which sided with the ranch and ruled that the project would never be sustainable and is therefore not compatible with Nevada policy. The project was formally abandoned in 2020. [ABSTRACT FROM AUTHOR]

Since 2002, National Aeronautics and Space Administration's Gravity Recovery and Climate Experiment (GRACE) allows scientists of various disciplines to analyze and map changes in total water storage globally. Although the raw data are available to the public, the process of viewing, manipulating, and analyzing GRACE data can be difficult for those without strong technological backgrounds in programming or geospatial software. This is particularly true for water managers in developing countries, where GRACE data could be a valuable asset for sustainable water resource management. To address this problem, we developed an open‐source utility for subsetting GRACE datasets to selected regions of interest and packaged that utility in a web application that allows water managers to quickly and easily access and visualize GRACE data. For a selected region, we use data from the three Global Land Data Assimilation System land surface models: Noah, variable infiltration capacity, and Catchment Land Surface Model, and decompose the GRACE data for total water storage into surface water, soil moisture, and groundwater components along with associated uncertainty estimates. The resulting groundwater data are in the form of groundwater storage changes over time, and a better understanding of groundwater storage trends helps water managers to more effectively respond to drought and agricultural demand in a selected region and thereby more sustainably manage groundwater resources. We demonstrate these uses in a case study from the Hindu‐Kush Himalayan region. [ABSTRACT FROM AUTHOR]

A public domain analytical reactive transport modeling tool ART3D, is developed in FORTRAN, which could be used for solving a system of a set of partial differential equations coupled with a first-order reaction network is presented. ART3D uses a novel analytic solution technique proposed by Clement and includes options for performing Monte Carlo simulations and automated parameter estimation.

This paper describes a technique for applying the transition probability geostatistics method for stochastic simulation to a MODFLOW model. Transition probability geostatistics has some advantages over traditional indicator kriging methods including a simpler and more intuitive framework for interpreting geologic relationships and the ability to simulate juxtapositional tendencies such as fining upward sequences. The indicator arrays generated by the transition probability simulation are converted to layer elevation and thickness arrays for use with the new Hydrogeologic Unit Flow package in MODFLOW 2000. This makes it possible to preserve complex heterogeneity while using reasonably sized grids and/or grids with nonuniform cell thicknesses., Introduction The essential feature of a Monte Carlo simulation is that multiple, equally probable hydrogeologic model realizations are generated and solved. Typically, the realizations are generated by combining random instances [...]

Interpolation of contaminant data can present a significant challenge due to sample clustering and sharp gradients in concentration. The research presented in this paper represents a study of commonly used interpolation schemes applied to three-dimensional plume characterization. Kriging, natural neighbor, and inverse distance weighted interpolation were tested on four actual data sets. The accuracy of each scheme was gauged using the cross-validation approach. Each scheme was compared to the other schemes and the effect of various interpolation parameters was studied. The kriging approach resulted in the lowest error at three of the four sites. The simpler and quicker inverse distance weighted approach resulted in a lower interpolation error on the other site and performed well overall. The natural neighbor method had the highest average error at all four sites in spite of the fact that it has been shown to perform well with clustered data. Another unexpected result was that the computationally expensive high order nodal functions resulted in reduced accuracy for the inverse distance weighted and natural neighbor approaches., Introduction The first step in developing a remediation strategy for a contaminated site is performing an accurate site characterization. Site characterization involves not only collecting the data but also interpreting [...]

Complex stratigraphy can be difficult to simulate in MODFLOW models. MODFLOW uses a structured grid that requires that each grid layer be continuous throughout the model domain. This makes it difficult to explicitly represent common features such as pinchouts and embedded seams in a MODFLOW model. In this paper, we describe a method for automatically generating MODFLOW-compatible grids from boundary-representation solid models. Solid models are data structures developed originally for computer-aided design applications that define the geometry of three-dimensional objects. Solid models can be used to represent arbitrarily complex stratigraphy. The elevations defined by the solids are then extracted from the solids in a manner that preserves the continuous-layer requirement imposed by MODFLOW. Two basic approaches are described: The first method adjusts the MODFLOW grid dimensions (layer elevations) to. fit the solid model boundaries, and the second method creates a regular MODFLOW grid and adjusts the materia l properties to match the changes in stratigraphy. One of the main benefits of using solid models to define stratigraphy for MODFLOW models is that it provides a grid-independent definition of the layer elevations that can be used to immediately re-create the MODFLOW grid geometry after any change to the grid resolution., Norman L. Jones (1) Trevor J. Budge (2) Alan M. Lemon (3) Alan K. Zundel (4) Introduction When building MODFLOW models (McDonald and Harbaugh 1988), source/sink objects such as rivers, [...]

Capacity to perform exercise is influenced by the health status of the performer. Exercise is defined as the oxidation of carbohydrate and fat to generate the adenosine triphosphate essential for muscle function. Exercise limitations are indicated in patients with cardiac disorders who expend more energy for breathing and to exercise muscle for a given power output than normal, healthy subjects.

The transformational and posttransformational regulation of skeletal muscle glycogen phosphorylase and pyruvate dehydrogenase (PDH) at three exercise power outputs was investigated. Findings showed that glycogen phosphorylase transformation is independent of increasing power outputs, despite increasing glycogenolytic flux, indicating that flux through glycogen phosphorylase is matched to energy required by posttransformational factors.

A comparison of plasma volume and ion regulation during increased leg exercise in humans after high and low carbohydrate depletion reveals that water flux between vascular and tissue regions during exercise occurs free of ion flux. The onset of exercise reveals the highest rate of water and ion flux. The weakening water flux in the later stages of the exercise are associated with metabolic hormonal variations, which result in modified osmotic gradients between contracting muscle and vascular region.

Computer-based terrain models have become increasingly popular as a tool for automating much of the geometrical data acquisition necessary for hydrologic analyses. An algorithm is presented that uses triangulated irregular networks (TINs) to accurately delineate drainage-basin boundaries. Boundary delineation can be performed for areas that drain to individual points or stream networks defined on the TIN. A special feature of the algorithm is that the segments of the stream network need not correspond to channel edges. This allows greater flexibility in defining stream networks on the TIN and makes it possible to apply the boundary delineation algorithm to urban areas where the stream networks may be dominated by manmade structures such as streets and canals or to rural areas where the terrain exhibits little relief. Once the basin boundaries are established, geometric parameters such as basin areas, slopes, and maximum flow distances are easily computed. These tools can be combined with hydrologic modeling software such as HEC-1 to create a comprehensive hydrologic modeling environment.

Three-dimensional computer models of construction sites and subsurface stratigraphy are useful for visualization, analysis, and design in geotechnical engineering. A useful technique for creating such models is the geometric technique known as 'solid modeling.' Solid modeling was originally developed in the fields of mechanical and aerospace engineering. In these fields, the shape and complexity of objects is relatively simple and well defined as compared to those of the earth's surface and subsurface. Accordingly, because of the complex nature of the surfaces involved, most available modeling systems are not well suited for modeling earth masses. To overcome this difficulty, a technique employing surfaces in the form of triangulated irregular networks (TINs) and set operations was developed. This technique facilitates the construction of complex three-dimensional models of earth masses from data that are typically available to geotechnical engineers. These data usually consist of surface-topographic surveys and borehole logs. Using the technique, a geotechnical engineer can create a three-dimensional model of a complex site. Complicated excavations can be modeled and cross sections, or 'fence' diagrams, can be constructed quickly and easily, anywhere on the model, to display the soil stratigraphy at the site. Volumes of excavations and fills also can be computed easily.

A finite element computer modeling system called TABS-2 has been developed by the U.S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi. TABS-2 has been used to model shallow water flow in estuaries. Accurate modeling of the flow in estuaries using TABS-2 requires the use of very large two-dimensional finite element meshes. The task of constructing such meshes has traditionally been the most time-consuming and error-prone part of the modeling process. Most automatic mesh-generation schemes are not well suited for estuarine modeling because the regions modeled are typically highly complex and irregular. As a result, the meshes are often constructed manually by coding the mesh in an ASCII file. Manual construction of large meshes is very tedious and can take several weeks to complete. To overcome this difficulty, a mesh generation scheme well suited for estuarine modeling has been developed involving a triangulation algorithm and a variety of mesh editing tools. The scheme makes it possible to generate large meshes of several thousand elements in a relatively short period of time. In addition, the scheme results in meshes with favorable geometric properties, leading to stability and accurate solutions.