646 research outputs found

    Water Management: Partnerships for Future Directions (Research and Testing Education Support Outreach)

    Get PDF
    The UWRL is uniquely positioned to form collaborations with USU departments, other academic institutions and water centers, government, and private sector organizations involved in addressing water issues. The strong and consistent support of the State of Utah illustrates the importance of water and the creation of knowledge to manage water in Utah and the surrounding western states. The scope of projects ranges from multimillion dollar partnerships related to soil and groundwater remediation with national impacts, to small scale projects related to outreach to a specific city or county public sector audience. The UWRL mission, the strategy used to accomplish the mission, a summary of accomplishments, examples of benefits delivered to the state, and an overview of future directions for the UWRL follow

    On the destruction of star-forming clouds

    Full text link
    Type II supernovae (SNe), probably the most important contributors to stellar feedback in galaxy formation, explode within the very dense star-forming clouds, where the injected energy is most easily radiated away. The efficiency of type II SNe in injecting energy into the interstellar medium (ISM) and in re-heating a fraction of the original star-forming cloud is estimated with the aid of a two-phase model for the ISM of the cloud. We argue that when SNe explode the star-forming cloud has already been partially destroyed by ionizing light and winds from massive stars. SN remnants (SNRs) will first cause the collapse of most of the cloud gas into cold fragments, until the diffuse hot phase has a low enough density to make further radiative losses negligible. This is completed in ~3 Myr, with a modest energy loss of ~5 per cent of the total budget. We compute that a fraction ranging from 5 to 30 per cent of the cloud is reheated to a high temperature (from 10^5 to 10^7 K); these numbers are very uncertain, due to the very complicated nature of the problem, and to the uncertain role of thermal evaporation. Small star-forming clouds, less massive than ~10^4 Msun, will be destroyed by a single SN. In all cases, a high fraction of the energy from type II SNe (~80 per cent for large clouds, smaller but still significant for small clouds) will be available for heating the ISM.Comment: 11 pages, 4 postscript figures included, uses mn2e.cls. In press on MNRA

    Parameter dependent convergence bounds and complexity measure for a class of conceptual hydrological models

    Get PDF
    We provide analytical bounds on convergence rates for a class of hydrologic models and consequently derive a complexity measure based on the Vapnik–Chervonenkis (VC) generalization theory. The class of hydrologic models is a spatially explicit interconnected set of linear reservoirs with the aim of representing globally nonlinear hydrologic behavior by locally linear models. Here, by convergence rate, we mean convergence of the empirical risk to the expected risk. The derived measure of complexity measures a model’s propensity to overfit data. We explore how data finiteness can affect model selection for this class of hydrologic model and provide theoretical results on how model performance on a finite sample converges to its expected performance as data size approaches infinity. These bounds can then be used for model selection, as the bounds provide a tradeoff between model complexity and model performance on finite data. The convergence bounds for the considered hydrologic models depend on the magnitude of their parameters, which are the recession parameters of constituting linear reservoirs. Further, the complexity of hydrologic models not only varies with the magnitude of their parameters but also depends on the network structure of the models (in terms of the spatial heterogeneity of parameters and the nature of hydrologic connectivity)

    A decision tree model to estimate the value of information provided by a groundwater quality monitoring network

    Get PDF
    Groundwater contaminated with nitrate poses a serious health risk to infants when this contaminated water is used for culinary purposes. To avoid this health risk, people need to know whether their culinary water is contaminated or not. Therefore, there is a need to design an effective groundwater monitoring network, acquire information on groundwater conditions, and use acquired information to inform management options. These actions require time, money, and effort. This paper presents a method to estimate the value of information (VOI) provided by a groundwater quality monitoring network located in an aquifer whose water poses a spatially heterogeneous and uncertain health risk. A decision tree model describes the structure of the decision alternatives facing the decision-maker and the expected outcomes from these alternatives. The alternatives include (i) ignore the health risk of nitrate-contaminated water, (ii) switch to alternative water sources such as bottled water, or (iii) implement a previously designed groundwater quality monitoring network that takes into account uncertainties in aquifer properties, contaminant transport processes, and climate (Khader, 2012). The VOI is estimated as the difference between the expected costs of implementing the monitoring network and the lowest-cost uninformed alternative. We illustrate the method for the Eocene Aquifer, West Bank, Palestine, where methemoglobinemia (blue baby syndrome) is the main health problem associated with the principal contaminant nitrate. The expected cost of each alternative is estimated as the weighted sum of the costs and probabilities (likelihoods) associated with the uncertain outcomes resulting from the alternative. Uncertain outcomes include actual nitrate concentrations in the aquifer, concentrations reported by the monitoring system, whether people abide by manager recommendations to use/not use aquifer water, and whether people get sick from drinking contaminated water. Outcome costs include healthcare for methemoglobinemia, purchase of bottled water, and installation and maintenance of the groundwater monitoring system. At current methemoglobinemia and bottled water costs of 150/personand 150/person and 0.6/baby/day, the decision tree results show that the expected cost of establishing the proposed groundwater quality monitoring network exceeds the expected costs of the uninformed alternatives and there is no value to the information the monitoring system provides. However, the monitoring system will be preferred to ignoring the health risk or using alternative sources if the methemoglobinemia cost rises to 300/personorthebottledwatercostincreasesto 300/person or the bottled water cost increases to 2.3/baby/day. Similarly, the monitoring system has value if the system can more accurately report actual aquifer concentrations and the public more fully abides by manager recommendations to use/not use the aquifer. The system also has value if it will serve a larger population or if its installation costs can be reduced, for example using a smaller number of monitoring wells. The VOI analysis shows how monitoring system design, accuracy, installation and operating costs, public awareness of health risks, costs of alternatives, and demographics together affect the value of implementing a system to monitor groundwater quality

    Ute Self-Determination in Setting Tribal Resource Development Policy

    Get PDF
    The Ute Indian Tribe of northeastern Utah has large land holdings rich in water and energy resources. Revenues from these sources have created capital that can potentially be used by the Tribe to further develop its resources and expand its agricultural and business enterprises. Realities, however, complicate this simple scenario in that the Tribal goals are broader than pure economic gain and that increased incomes may mean sacrifices in terms of these other goals. The Tribe faces the problem of how best to develop its water resources in a way that best meets its multiplicity of needs. The research team worked with the Utes to articulate their resources development goals, to operationalize those goals through the identification of measureable indicators, to identify promising development policies, to predict what those policies would achieve through changing the indicators, and to set before the Utes the trade offs among the goals. The procedures used in working with the Indians are described. The results were used to construct and use a linear programming model to identify Ute-specific development policies with their impacts and the trade offs among them. The model provides a framework that the Tribe can use to assess the alternatives for developing its water resources

    A Methodology for Public-Planner Interaction in Multiobjective Project Planning and Evaluation

    Get PDF
    A review of current multiple objective planning techniques is presented. A critique of certain classes of these techniques is offered, especially in terms of the degree to which they facilitate certain information needs of the planning process. Various tools in operations research are used to constructed a new multiple objective planning methodology, called the Vector Optimization Decision Convergence Algorithm (VODCA). An application of the methodology pertaining to water resources development in Utah is documented

    Estimation of Surface Soil Moisture in Irrigated Lands by Assimilation of Landsat Vegetation Indices, Surface Energy Balance Products, and Relevance Vector Machines

    Get PDF
    Spatial surface soil moisture can be an important indicator of crop conditions on farmland, but its continuous estimation remains challenging due to coarse spatial and temporal resolution of existing remotely-sensed products. Furthermore, while preceding research on soil moisture using remote sensing (surface energy balance, weather parameters, and vegetation indices) has demonstrated a relationship between these factors and soil moisture, practical continuous spatial quantification of the latter is still unavailable for use in water and agricultural management. In this study, a methodology is presented to estimate volumetric surface soil moisture by statistical selection from potential predictors that include vegetation indices and energy balance products derived from satellite (Landsat) imagery and weather data as identified in scientific literature. This methodology employs a statistical learning machine called a Relevance Vector Machine (RVM) to identify and relate the potential predictors to soil moisture by means of stratified cross-validation and forward variable selection. Surface soil moisture measurements from irrigated agricultural fields in Central Utah in the 2012 irrigation season were used, along with weather data, Landsat vegetation indices, and energy balance products. The methodology, data collection, processing, and estimation accuracy are presented and discussed. © 2016 by the authors

    Hydrodynamical simulations of the decay of high-speed molecular turbulence. I. Dense molecular regions

    Full text link
    We present the results from three dimensional hydrodynamical simulations of decaying high-speed turbulence in dense molecular clouds. We compare our results, which include a detailed cooling function, molecular hydrogen chemistry and a limited C and O chemistry, to those previously obtained for decaying isothermal turbulence. After an initial phase of shock formation, power-law decay regimes are uncovered, as in the isothermal case. We find that the turbulence decays faster than in the isothermal case because the average Mach number remains higher, due to the radiative cooling. The total thermal energy, initially raised by the introduction of turbulence, decays only a little slower than the kinetic energy. We discover that molecule reformation, as the fast turbulence decays, is several times faster than that predicted for a non-turbulent medium. This is caused by moderate speed shocks which sweep through a large fraction of the volume, compressing the gas and dust. Through reformation, the molecular density and molecular column appear as complex patterns of filaments, clumps and some diffuse structure. In contrast, the molecular fraction has a wider distribution of highly distorted clumps and copious diffuse structure, so that density and molecular density are almost identically distributed during the reformation phase. We conclude that molecules form in swept-up clumps but effectively mix throughout via subsequent expansions and compressions.Comment: 12 pages, 12 figures; For a version of the article with higher resolution figures, see http://star.arm.ac.uk/preprints/381.p
    • …
    corecore