United States Bureau of Reclamation

Formulas are derived for the changes of water pressures during an earthquake for the case of a straight dam with a vertical up-stream face. The vibrations in the earthquake are assumed horizontal in a direction perpendicular to the darn. A formula is obtained involving a series of sines (Equation (31)). This series, however, may be replaced with satisfactory approximation by a simpler formula (Equation (49)). The results are also expressed in the following manner: The pressures are the same as if a certain body of water were forced to move back and forth with the dam while the remainder of the reservoir is left inactive; Fig. 3 shows approximately the shape of this body of water. The influence of the dynamic action of the water is found to be neither excessively large nor negligible.

Expansive clay soils have been encountered at the sites of structures throughout the western United States. Inasmuch as most of these structures are hydraulic, the normal difficulties encountered when expansive clays are present in the subgrade foundation are greatly magnified. As a result of some of the difficulties that have been experienced, considerable research testing has been undertaken so ·that expansive clays can be recognized and their potential swelling properties anticipated.

Abstract This work advances a unified approach to process‐based hydrologic modeling to enable controlled and systematic evaluation of multiple model representations (hypotheses) of hydrologic processes and scaling behavior. Our approach, which we term the Structure for Unifying Multiple Modeling Alternatives (SUMMA), formulates a general set of conservation equations, providing the flexibility to experiment with different spatial representations, different flux parameterizations, different model parameter values, and different time stepping schemes. In this paper, we introduce the general approach used in SUMMA, detailing the spatial organization and model simplifications, and how different representations of multiple physical processes can be combined within a single modeling framework. We discuss how SUMMA can be used to systematically pursue the method of multiple working hypotheses in hydrology. In particular, we discuss how SUMMA can help tackle major hydrologic modeling challenges, including defining the appropriate complexity of a model, selecting among competing flux parameterizations, representing spatial variability across a hierarchy of scales, identifying potential improvements in computational efficiency and numerical accuracy as part of the numerical solver, and improving understanding of the various sources of model uncertainty.

A new data set enhances the abilities of researchers and decision‐makers to assess possible future climates, explore societal impacts, and approach policy responses from a risk‐based perspective. The data set, which consists of a library of 112 fine‐resolution climate projections, based on 16 climate models and three greenhouse gas emissions scenarios, is now publicly available. Monthly climate projections from 1950 to 2099 were downscaled to a spatial resolution of ⅛° (about 140 square kilometers per grid cell) covering the conterminous United States and portions of Canada and Mexico. For the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, climate modeling groups produced hundreds of simulations of past and future climates. The colocation of these simulations in a single archive (at the Program for Climate Model Diagnosis and Intercomparison at Lawrence Livermore National Laboratory (LLNL), established to facilitate assessment of general circulation models, or GCMs) and the conversion of all results to a common data format have made probabilistic, multi‐model projections and impact assessments practical. A remaining issue is that the spatial scale of climate model output is typically too coarse for regional impact studies. Multiple downscaling approaches exist for deriving regional climate from coarse‐resolution model output; these approaches are typically applied on an ad hoc basis to a particular region.

A data set of observed daily precipitation, maximum and minimum temperature, gridded to a 1/16° (~6 km) resolution, is described that spans the entire country of Mexico, the conterminous U.S. (CONUS), and regions of Canada south of 53° N for the period 1950-2013. The dataset improves previous products in spatial extent, orographic precipitation adjustment over Mexico and parts of Canada, and reduction of transboundary discontinuities. The impacts of adjusting gridded precipitation for orographic effects are quantified by scaling precipitation to an elevation-aware 1981-2010 precipitation climatology in Mexico and Canada. Differences are evaluated in terms of total precipitation as well as by hydrologic quantities simulated with a land surface model. Overall, orographic correction impacts total precipitation by up to 50% in mountainous regions outside CONUS. Hydrologic fluxes show sensitivities of similar magnitude, with discharge more sensitive than evapotranspiration and soil moisture. Because of the consistent gridding methodology, the current product reduces transboundary discontinuities as compared with a commonly used reanalysis product, making it suitable for estimating large-scale hydrometeorologic phenomena.

An array of alternating anion and cation exchange membranes can be used to generate electric power from the free energy of mixing of river and sea waters. A simple mathematical model, which predicts experimental results well, is useful in exploring conditions for optimization of the process. Major, but not impossible, improvements in technology would be required to bring the cost of power from the dialytic battery into line with foreseeable energy prices.

1R37. Hydraulics of Stepped Chutes and Spillways. - H Chanson (Dept of Civil Eng, Univ of Queensland, Brisbane, Australia). Balkema Publ, Rotterdam, Netherlands. 2002. 384 pp. ISBN 90-5809-352-2. $105.00.Reviewed by AS Paintal (Eng Dept, Metropolitan Water Reclamation District, 100 E Erie St, Chicago IL 60611).This book provides a comprehensive coverage of most of the engineering topics in the hydraulic design of stepped chutes and spillways. The stepped channels and chutes have been in use for more than 3500 years, but there is no publication on the hydraulic design of these structures. Since 1980s, there has been a renewed interest in these structures for water and wastewater treatment plants and flood control facilities due to development of new construction techniques and materials. This book fulfills the need for presenting the state of the art in the stepped chute hydraulics. It helps students as well as practicing engineers and researchers get a feel for various aspects of the stepped chute hydraulics. The book is organized in ten chapters and nine appendices. The chapters provide an orderly development of the subject. Chapter 1 gives a brief introduction of the subject and discusses the organization of the book. A stepped chute is defined as a channel with a series of drops in the channel bed. The flow in this channel is classified based upon the geometry of steps and flow rate. Three regimes of flow are defined, they are: nappe flow regime at low flow rates, transition flow regime at intermediate flow rate, and skimming flow regime at large flow rates. Chapter 2 provides a brief history on the development of the design and construction methods and materials for stepped chutes and spillways. The stepped cascades have been in use for aqueducts and fountains since historic times. Chapter 3 deals with the hydraulics of nappe flow regime. The nappe flow is defined as a succession of free falling sheets of water with the jet impinging on the next lower step. On the lower step, either the flow is supercritical, or a full or partial hydraulic jump is formed. The energy is lost in impact and in hydraulic jump. Chapter 4 is concerned with transition flow regime that is defined as transition from nappe flow regime to skimming flow regime. This regime is associated with the severe hydrodynamic fluctuations and is, therefore, avoided in the design. Chapter 5 discusses the skimming flow regime, in which the flow skims over the steps with the external edges of the steps forming a virtual-channel bed. The energy is dissipated due to vortices that are formed in each corner. As the dissolved oxygen concentration is a prime indicator of the quality of water, Chapter 6 discusses the aeration and de-aeration characteristics of cascading water. The cascades are very efficient means of aeration due to turbulent mixing and air entrainment. In Chapter 7, new design methods and guidelines are presented for various applications of stepped chutes. The design procedures for stepped spillways, stepped channels at the toe of the chute, stepped fountains, and water staircases are discussed in detail with a number of examples. Historic accidents and failures of hydraulic structures with stepped chutes and channels are discussed in Chapter 8. Recommendations are formulated for safe and efficient design. The author recommends avoiding transition flow regime as hydrodynamic fluctuations are inherent in this flow regime. Quality of construction methods and materials, and good maintenance practices are also emphasized. Chapter 9 deals with the flow instabilities and unsteady wave phenomena that occur in the stepped channels and spillways. Basic theory is provided for the wave phenomena, and the documented experiences are reviewed. Chapter 10 provides a summary and makes recommendations for future research on the air-water gas transfer process in nappe and skimming flow regimes, hydraulic characteristics of transition and skimming flow regimes, and hydrodynamic loads on the steps. There are nine appendices. Appendix 1 gives a list of physical and chemical properties of fluid in SI units, while Appendix 2 provides a table for unit conversions. A method for computing nappe trajectory is given in Appendix 3, and Appendix 4 explains a procedure for computing bubble rise velocity. A method for modeling form drag and resistance to flow is given in Appendix 5, and void fraction distribution in chute flow is discussed in Appendix 6. A method of computing the flow in stepped chute for skimming flow regime is given in Appendix 7, and a procedure for modeling air-water gas transfer in skimming flow regime is presented in Appendix 8. Appendix 9 provides a procedure for reporting errors and omissions in the book. A list of symbols, a comprehensive glossary of technical terms, and a list of references are also included in the book. The hydraulics of stepped chutes differs from the classical hydraulics of smooth channels and is not usually taught in schools. The books on classical hydraulics do not cover this topic either. The purpose of the book has been to provide basic hydraulic theory related to designing stepped chutes and spillways. The book is based on a state-of-the-art-review of literature and research reports. The book is very well illustrated with a large number of charts and photographs. The photographs show hydraulic structures built over the years that incorporate stepped chutes for energy dissipation, flood control, and aesthetics (landscaping). Hydraulics of Stepped Chutes and Spillways is a useful contribution to the field of hydraulics. The book may be used as a text for an undergraduate (elective) or a graduate course in the hydraulics of stepped chutes. The book will be useful for engineers working in the area of design and research.

The recent implementation of soil and drinking water screening guidance values for two perfluorochemicals (PFCs), perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) by the U.S. Environmental Protection Agency (EPA), reflects the growing concerns regarding the presence of these persistent and bioaccumulative chemicals in the natural environment. Previous work has established the potential risk to the environment from the land application of industrially contaminated biosolids, but studies focusing on environmental risk from land application of typical municipal biosolids are lacking. Thus, the present study investigated the occurrence and fate of PFCs from land-applied municipal biosolids by evaluating the levels, mass balance, desorption, and transport of PFCs in soils receiving application of municipal biosolids at various loading rates. This study is the first to report levels of PFCs in agricultural soils amended with typical municipal biosolids. PFOS was the dominant PFC in both biosolids (80-219 ng/g) and biosolids-amended soil (2-483 ng/g). Concentrations of all PFCs in soil increased linearly with increasing biosolids loading rate. These data were used to develop a model for predicting PFC soil concentrations in soils amended with typical municipal biosolids using cumulative biosolids loading rates. Mass balance calculations comparing PFCs applied vs those recovered in the surface soil interval indicated the potential transformation of PFC precursors. Laboratory desorption experiments indicated that the leaching potential of PFCs decreases with increasing chain length and that previously derived organic-carbon normalized partition coefficients may not be accurate predictors of the desorption of long-chain PFCs from biosolids-amended soils. Trace levels of PFCs were also detected in soil cores from biosolids-amended soils to depths of 120 cm, suggesting potential movement of these compounds within the soil profile over time and confirming the higher transport potential for short-chain PFCs in soils amended with municipal biosolids.

A method is presented for the approximate estimation of the time for progression of internal erosion and piping, and development of a breach leading to failure in embankment dams and their foundations. The method accounts for the nature of the soils in the dam core, the foundation, and the materials in the downstream zone of the dam. Guidance is also provided on the detectability of internal erosion and piping, taking account of the mechanism of initiation, continuation, and progression to form a breach, for internal erosion and piping in the embankment, the foundation and from the embankment to foundation. It is shown that in many dams which have poor internal erosion and seepage control and are constructed mainly of earthfill, the time for potential development of piping is short, and for these dams continuous monitoring of seepage or surveillance would be needed to detect the piping in time to give warning of possible failure, and to give time to attempt intervention to prevent the failure.

Animal manure is applied to agricultural land as a means to provide crop nutrients. However, animal manure often contains antibiotics as a result of extensive therapeutic and subtherapeutic use in livestock production. The objective of this study was to evaluate plant uptake of a sulfonamide-class antibiotic, sulfamethazine, in corn (Zea mays L.), lettuce (Lactuca sativa L.), and potato (Solanum tuberosum L.) grown in a manure-amended soil. The treatments were 0, 50, and 100 microg sulfamethazine mL(-1) manure applied at a rate of 56 000 L ha(-1). Results from the 45-d greenhouse experiment showed that sulfamethazine was taken up by all three crops, with concentrations in plant tissue ranging from 0.1 to 1.2 mg kg(-1) dry weight. Sulfamethazine concentrations in plant tissue increased with corresponding increase of sulfamethazine in manure. Highest plant tissue concentrations were found in corn and lettuce, followed by potato. Total accumulation of sulfamethazine in plant tissue after 45 d of growth was less than 0.1% of the amount applied to soil in manure. These results raise potential human health concerns of consuming low levels of antibiotics from produce grown on manure-amended soils.

Abstract This paper presents a short history of water resources systems analysis from its beginnings in the Harvard Water Program, through its continuing evolution toward a general field of water resources systems science. Current systems analysis practice is widespread and addresses the most challenging water issues of our times, including water scarcity and drought, climate change, providing water for food and energy production, decision making amid competing objectives, and bringing economic incentives to bear on water use. The emergence of public recognition and concern for the state of water resources provides an opportune moment for the field to reorient to meet the complex, interdependent, interdisciplinary, and global nature of today's water challenges. At present, water resources systems analysis is limited by low scientific and academic visibility relative to its influence in practice and bridled by localized findings that are difficult to generalize. The evident success of water resource systems analysis in practice (which is set out in this paper) needs in future to be strengthened by substantiating the field as the science of water resources that seeks to predict the water resources variables and outcomes that are important to governments, industries, and the public the world over. Doing so promotes the scientific credibility of the field, provides understanding of the state of water resources and furnishes the basis for predicting the impacts of our water choices.

There are a growing number of large-scale, complex hydrologic models that are capable of simulating integrated surface and subsurface flow. Many are coupled to land-surface energy balance models, biogeochemical and ecological process models, and atmospheric models. Although they are being increasingly applied for hydrologic prediction and environmental understanding, very little formal verification and/or benchmarking of these models has been performed. Here we present the results of an intercomparison study of seven coupled surface-subsurface models based on a series of benchmark problems. All the models simultaneously solve adapted forms of the Richards and shallow water equations, based on fully 3-D or mixed (1-D vadose zone and 2-D groundwater) formulations for subsurface flow and 1-D (rill flow) or 2-D (sheet flow) conceptualizations for surface routing. A range of approaches is used for the solution of the coupled equations, including global implicit, sequential iterative, and asynchronous linking, and various strategies are used to enforce flux and pressure continuity at the surface-subsurface interface. The simulation results show good agreement for the simpler test cases, while the more complicated test cases bring out some of the differences in physical process representations and numerical solution approaches between the models. Benchmarks with more traditional runoff generating mechanisms, such as excess infiltration and saturation, demonstrate more agreement between models, while benchmarks with heterogeneity and complex water table dynamics highlight differences in model formulation. In general, all the models demonstrate the same qualitative behavior, thus building confidence in their use for hydrologic applications.

Landscape connectivity, the extent to which a landscape facilitates the movements of organisms and their genes, faces critical threats from both fragmentation and habitat loss. Many conservation efforts focus on protecting and enhancing connectivity to offset the impacts of habitat loss and fragmentation on biodiversity conservation, and to increase the resilience of reserve networks to potential threats associated with climate change. Loss of connectivity can reduce the size and quality of available habitat, impede and disrupt movement (including dispersal) to new habitats, and affect seasonal migration patterns. These changes can lead, in turn, to detrimental effects for populations and species, including decreased carrying capacity, population declines, loss of genetic variation, and ultimately species extinction.

ABSTRACT: Water management agencies seek the next generation of modeling tools for planning and operating river basins. Previous site‐specific models such as U.S. Bureau of Reclamation's (USBR) Colorado River Simulation System and Tennessee Valley Authority's (TVA) Daily Scheduling Model have become obsolete; however, new models are difficult and expensive to develop and maintain. Previous generalized river basin modeling tools are limited in their ability to represent diverse physical system and operating policy details for a wide range of applications. RiverWare(tm), a new generalized river basin modeling tool, provides a construction kit for developing and running detailed, site‐specific models without the need to develop or maintain the supporting software within the water management agency. It includes an extensible library of modeling algorithms, several solvers, and a rich “language” for the expression of operating policy. Its point‐and‐click graphical interface facilitates model construction and execution, and communication of policies, assumptions and results to others. Applications developed and used by the TVA and the USBR demonstrate that a wide range of operational and planning problems on widely varying basins can be solved using this tool.

Crop uptake of perfluoroalkyl acids (PFAAs) from biosolids-amended soil has been identified as a potential pathway for PFAA entry into the terrestrial food chain. This study compared the uptake of PFAAs in greenhouse-grown radish (Raphanus sativus), celery (Apium graveolens var. dulce), tomato (Lycopersicon lycopersicum), and sugar snap pea (Pisum sativum var. macrocarpon) from an industrially impacted biosolids-amended soil, a municipal biosolids-amended soil, and a control soil. Individual concentrations of PFAAs, on a dry weight basis, in mature, edible portions of crops grown in soil amended with PFAA industrially impacted biosolids were highest for perfluorooctanoate (PFOA; 67 ng/g) in radish root, perfluorobutanoate (PFBA; 232 ng/g) in celery shoot, and PFBA (150 ng/g) in pea fruit. Comparatively, PFAA concentrations in edible compartments of crops grown in the municipal biosolids-amended soil and in the control soil were less than 25 ng/g. Bioaccumulation factors (BAFs) were calculated for the root, shoot, and fruit compartments (as applicable) of all crops grown in the industrially impacted soil. BAFs were highest for PFBA in the shoots of all crops, as well as in the fruit compartment of pea. Root-soil concentration factors (RCFs) for tomato and pea were independent of PFAA chain length, while radish and celery RCFs showed a slight decrease with increasing chain length. Shoot-soil concentration factors (SCFs) for all crops showed a decrease with increasing chain length (0.11 to 0.36 log decrease per CF2 group). The biggest decrease (0.54-0.58 log decrease per CF2 group) was seen in fruit-soil concentration factors (FCFs). Crop anatomy and PFAA properties were utilized to explain data trends. In general, fruit crops were found to accumulate fewer long-chain PFAAs than shoot or root crops presumably due to an increasing number of biological barriers as the contaminant is transported throughout the plant (roots to shoots to fruits). These data were incorporated into a preliminary conceptual framework for PFAA accumulation in edible crops. In addition, these data suggest that edible crops grown in soils conventionally amended for nutrients with biosolids (that are not impacted by PFAA industries) are unlikely a significant source of long-chain PFAA exposure to humans.

Managed relocation is defined as the movement of species, populations, or genotypes to places outside the areas of their historical distributions to maintain biological diversity or ecosystem functioning with changing climate. It has been claimed that a major extinction event is under way and that climate change is increasing its severity. Projections indicating that climate change may drive substantial losses of biodiversity have compelled some scientists to suggest that traditional management strategies are insufficient. The managed relocation of species is a controversial management response to climate change. The published literature has emphasized biological concerns over difficult ethical, legal, and policy issues. Furthermore, ongoing managed relocation actions lack scientific and societal engagement. Our interdisciplinary team considered ethics, law, policy, ecology, and natural resources management in order to identify the key issues of managed relocation relevant for developing sound policies that support decisions for resource management. We recommend that government agencies develop and adopt best practices for managed relocation.

A well adjacent to a river will take a portion of its supply from the river A theoretical formula is developed which permits the draft on the river to be computed in terms of the distance of the well from the river, the properties of the aquifer, and time. The formula applies where the river can be considered to flow in a straight course which extends for a considerable distance both upstream and downstream from the well location.

9R37. Engineering Fluid Mechanics. - WP Graebel (Dept of Mech Eng and Appl Mech, Univ of Michigan, Ann Arbor MI). Taylor & Francis Publ, New York NY. 2001. 676 pp. ISBN 1-560-32711-1. $89.95.Reviewed by AS Paintal (Eng Dept, Metropolitan Water Reclamation District, 100 E Erie St, Chicago IL 60611).This is a text for an introductory course in engineering fluid mechanics. Fluid mechanics is one of the basic courses required for an undergraduate degree in engineering. The purpose of the book is to provide basic theory as well as to develop analytical skills in the engineering students. The book helps the students to get a feel for flow patterns; pressure variations; and continuity, energy, and momentum principles. The book is organized into 12 chapters and seven appendices. The chapters provide orderly development of the subject. Chapter 1 gives a brief introduction of the subject. Fluid properties are defined and procedures for solving engineering problems are suggested. Chapter 2 deals with hydrostatics and pressure variations and distributions in fluids subjected to rigid body accelerations. Chapter 3 is devoted to fluid dynamics. The ideas of control volume and control surface are introduced, and concepts of incompressibility and discharge are defined. The fundamental equations of fluid mechanics in one dimension are formulated using the concepts of conservation of mass, linear momentum, angular momentum, and energy. Application of these equations for problem solving is emphasized. In Chapter 4, the differential equations using the continuity, energy, and momentum concepts are derived in two- and three-dimensions. The concepts of potential flow are also introduced. Chapter 5 deals with the dimensional analysis and model-prototype relationships. Chapters 6 and 7 concern laminar and turbulent flows. The equation for laminar flows between parallel plates and circular tubes are formulated, and the concept of boundary layer is introduced in Chapter 6. The concept is further developed for turbulent boundary layers in Chapter 7. Turbulent flow in pipes is thoroughly analyzed. The chapter also covers drag and lift forces. Chapter 8 considers the hydraulics of open channel, and the effect of gravity on flow is analyzed. Chapter 9 deals with the compressible flow problems and the effect of Mach Number on the flow. In Chapter 10, various flow, pressure, and velocity measurement techniques are evaluated. Chapter 11 is devoted to hydraulic machines. In Chapter 12, suggestions are made for additional study of various engineering disciplines involving the principles of fluid mechanics. There are a number of solved problems included in every chapter to explain the principles involved. At the end of each chapter, a set of unsolved problems is provided for practice. The answers to even-numbered problems are given at the end of the book. There are seven appendices. Appendix A deals with conversion of units and gives useful constants. Appendix B summarizes the fluid properties of water air and other common fluids in British (US) and SI units. Appendix C covers mathematical aids used for solving fluid mechanics problems. Appendix D provides compressible flow tables for air k=1.4. A brief history of fluid mechanics is given in Appendix E. Appendix F’s focus is on the design of a pump system. The purpose is to demonstrate how the design and other broader issues are considered in the design. Engineering Fluid Mechanics provides a balanced treatment of engineering fluid mechanics. The theory as well as problem solving skills are emphasized. The book should be considered for adoption as a text for an introductory undergraduate course in fluid mechanics. It will be useful for engineers working in the area of fluid mechanics or preparing for the examination leading to a professional engineer license.

Risk assessment studies considering the failure of embankment dams often require the prediction of basic geometric and temporal parameters of a breach, or the estimation of peak breach outflows. Many of the relations most commonly used to make these predictions were developed from statistical analyses of data collected from historic dam failures. The prediction uncertainties of these methods are widely recognized to be very large, but have never been specifically quantified. This paper presents an analysis of the uncertainty of many of these breach parameter and peak flow prediction methods. Application of the methods and the uncertainty analysis are illustrated through a case study of a risk assessment recently performed by the Bureau of Reclamation for a large embankment dam in North Dakota.

Abstract Airborne bathymetric LiDAR was collected for 220 river kilometres in the Yakima and Trinity River Basins in the USA. Concomitant with the aerial data collection, ground surveys of the river bed were performed in both basins. We assess the quality of the bathymetric LiDAR survey from the perspective of its application toward creating accurate, precise and complete streambed topography for numerical modelling and geomorphological assessment. Measurement error is evaluated with respect to ground surveys for magnitude and spatial variation. Analysis of variance statistics indicate that residuals from two independent ground surveys in similar locations do not come from the same population and that mean errors at different study locations also come from different populations. Systematic error indicates a consistent bias in the data and random error falls within values of expected precision. Published in 2007 by John Wiley & Sons, Ltd.