bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pathogens
Authors: Gerba Charles P 
Published: April 2006

AbstractWater plays a major role in human disease by serving as the vehicle for the transmission of disease‐causing microorganisms (pathogens), and as a habit for some of their insect hosts. Worldwide, it is estimated that a child dies every 8 s from water‐related diseases. New pathogens, which are transmitted by water, are recognized on a continuing basis providing challenges to both watershed management and water treatment technologies. Microorganisms transmitted by the fecal‐oral route or waterborne pathogens are the most widespread since many may occur in the feces of both infected humans and animals. All surface waters can be expected to contain waterborne pathogens at one time or another. Feces from animals and sewage discharges contaminate surface waters. Groundwater may be contaminated from infiltration from land disposed human and animal wastes or water contaminated with these wastes, septic tanks, and unlined landfills. Contamination of surface and groundwater is always greatest after rainfall events due to the flushing of accumulated animal feces and infiltration of soils. Waterborne pathogens may survive for days to months in the environment. Survival of pathogens in the water environment is largely dependent on temperature and sunlight exposure.
Trophic Dynamics
Authors: Cleveland Cory C , Townsend Alan R , McKnight Diane M 
Published: April 2006

Abstract
The carbon (C) and water cycles are intimately linked in terrestrial ecosystems. Thus, an understanding of the processes regulating transfers of water in terrestrial ecosystems requires an understanding of the carbon cycle, and in particular, the factors constraining carbon movement in the soil‐plant‐atmosphere continuum and through trophic levels in ecosystems. The linkages between the C and the water cycles are mediated primarily through biological processes, and are bidirectional in nature. For example, precipitation (and hence ecosystem water availability) strongly regulates plant growth and biogeochemical cycling in soils. Subsequently, plant growth and soil biogeochemistry strongly influence evaporation and atmospheric water vapor (and hence precipitation). Plant growth and soil processes are also cyclically linked. Thus, plant and soil interactions can have important implications for water cycling. However, while major climatic variables (including precipitation) may drive biological patterns and processes at large scales, other ecological interactions also regulate both plant and soil processes. An appreciation of these ecological factors is important to understanding the relationship between C and water, and to predicting how global environmental change is likely to affect the interactions between the C and water cycles.
Satellite‐Based Analysis of Ecological Controls for Land‐Surface Evaporation Resistance
Authors: Running Steven W , Kimball John S 
Published: April 2006

Abstract
Lack of available water constrains ecological processes for two‐thirds of the earth's biosphere. These water limitations are manifested as either physical water deficiency or as a chemical unavailability of water as a result of being frozen. This article summarizes global principles of water limitations on the biosphere, and physiological limitations on plants. It presents hydrometeorological principles of evapotranspiration and organizing logic of the soil–vegetation–atmosphere transfer models commonly used to compute evapotranspiration. We then introduce remote sensing from both optical/thermal and active/passive microwave sensors for calculating landscape scale evapotranspiration. Finally, we offer a multisensor‐based integrated surface resistance to define landscape water availability under all conditions.
Groundwater Microbial Communities
Authors: McKinley James P , Fredrickson James K , Colwell Frederick S 
Published: April 2006

AbstractMicrobial communities in aquifers consist of diverse interactive individuals which break down complex organic matter for metabolic energy. Microbes are adapted to function over environmental conditions ranging from freezing to boiling, acidic to alkaline. They can use oxygen as a reducible metabolite during organic carbon oxidation, but, since oxygen is rapidly depleted in subsurface environments, different groups of organisms may also rely upon other compounds such as reducible metals or upon fermentation. Community members are interdependent, but compete for resources, and communities often have predominant groups that rely on recognizable chemical pathways such as sulfate reduction. The predominant group varies spatially and temporally, as the available nutrients change or are depleted.
Rainfall Excess Overland Flow
Authors: Smith Roger E , Goodrich David C 
Published: April 2006

Abstract
One of the processes that can generate surface runoff is rainfall excess, which is a process controlled at the surface of the soil. This occurs when rainfall reaches the soil at a rate in excess of the soil's ability to absorb, which is called infiltrability. This dynamic property can in uniform soil be described by a rather well‐developed infiltration theory. Surface water flow toward a receiving channel may in geometrically simple conditions be described by the kinematic or diffusive wave equations. The surface water is in continuous interaction with the soil's changing infiltrability. Both infiltration theory and surface flow equations are introduced here, and the interactions and complexities arising from spatial variations are discussed. These processes are incorporated in modern hydrologic response models, using numerical solutions as well as analytic solutions. The application of this theory in hydrology, however, must be informed by scale considerations and the appropriate treatment of natural complexities. Some scale limitations and some approximate methods for treating spatial soil variations are illustrated in this article, with reference to relevant literature.
Isotope Hydrograph Separation of Runoff Sources
Authors: Buttle Jim M 
Published: April 2006

AbstractUse of isotopic tracers to characterize water ages, origins, and flow pathways in drainage basins is reviewed, along with the assumptions that underlie isotopic hydrograph separations (IHSs). Points of agreement regarding the use of the IHS approach in small drainage basins are examined, as are some of the key challenges associated with application of the approach in future research. Despite a growing awareness of the limitations of IHS, the method offers a powerful tool to examine a number of critical issues in hydrology, particularly when employed in conjunction with hydrometric techniques and the use of other tracers. These issues include the estimation of water residence times, the identification of process thresholds, the assessment of hydrological response to land use change, and the use of isotopic data to calibrate and test hydrological models.
Land Use and Land Cover Effects on Runoff Processes: Urban and Suburban Development
Authors: Endreny Theodore A 
Published: April 2006

AbstractUrban and suburban development alters watershed imperviousness and connectivity, resulting in alterations to the hydrologic and hydraulic runoff response. Stormwater conveyance devices have been incorporated into most development to address the goal of floodwater removal for protection of life and property. Urban and suburban development laws generally consider the stormwater drainage system as part of the basic infrastructure and leave right of way and space to locate the component parts. Drainage systems are designed to protect life, enable vehicular access, extend pavement life cycle, control the volume and velocity of stormwater runoff along curbs and gutters, and convey stormwater runoff to natural or human constructed drainage ways and receiving waters. Engineering equations have been developed to design construction for optimal runoff behavior, such as timing, volume, and rate, into, through, and from conveyance devices. Design equations are also utilized for assessing the performance of constructed environments, to ascertain whether stormwater devices need rehabilitation or expansion. New frontiers in stormwater include model spatially distributed development that incorporates high‐density elevation maps, radar rainfall, and details of remotely sensed infrastructure as well as ecological restoration simulation, including groundwater and river remediation for wildlife and recreation.
Land Use and Land Cover Effects on Runoff Processes: Fire
Authors: Luce Charles H 
Published: April 2006

AbstractFire dramatically alters hydrologic processes in many regions of the world. Individual fires reduce vegetation and change soil characteristics, sometimes producing dramatic runoff events in the years shortly after a fire. The greatest determinant of the effect of fire on runoff generation is the severity of the fire, which relates to the frequency of fires and other climatic and vegetation characteristics. Severe fires can produce hydrophobic soils or increase risk of soil surface sealing, reducing infiltration rates. Measurements of the spatial pattern of water repellent soils are useful for estimating potential runoff from postfire storms. The most severe events occur during convective storms, so the spatial extent of individual postfire floods is generally limited in extent. Recovery of water repellent soils is relatively rapid, with significant reductions occurring within a few years. Longer‐term changes to hydrology are related to the reduced evapotranspiration caused by loss of vegetation biomass. In forests, changes to annual water balances may last decades.
Rainfall‐Runoff Models for Real‐Time Forecasting
Authors: Todini Ezio 
Published: April 2006

AbstractThis article describes the use of rainfall‐runoff models within the frame of real‐time flood forecasting and warning. After assessing the requirements of real‐time flood forecasting systems, some of the more well known ones available for operational purposes are briefly mentioned. The different types of rainfall‐runoff models used in practice are then presented, within the framework set on the one hand by the operational system requirements, and on the other hand by the historical evolution of research and development in the fields of hydrological and meteorological forecasting. After discussing the problems of real‐time updating and of the assessment of the predictive uncertainty, two example applications are illustrated. The article concludes with a description of current and future research themes for extending the forecasting lead time, assessing forecasting uncertainty, and appropriately communicating it to the end users.
Rainfall‐Runoff Modeling for Flood Frequency Estimation
Authors: Lamb Rob 
Published: April 2006

AbstractRainfall‐runoff models are amongst the most important tools for the practical solution of flood estimation problems, as well as for theoretical investigations of controls on the flood frequency curve or for analysis of catchment and climate change. This article aims to provide a discussion of the use of rainfall‐runoff modeling for flood estimation, with an emphasis on overall methodology rather than on specific hydrological models. After a brief introduction to some basic concepts of flood analysis, the article describes the two main approaches for applying rainfall‐runoff models in flood estimation, namely, event‐based modeling and continuous simulation. The theoretical basis for each approach is described along with typical model structures. Topics covered include rainfall models, hydrological model calibration and the estimation of parameters for modeling at ungauged or data‐poor sites. The article concentrates on the development of the continuous simulation method, and includes a number of illustrations of its application, both from research studies and applied hydrology.
Rainfall‐Runoff Modeling for Integrated Basin Management
Authors: Leavesley George 
Published: April 2006

AbstractIntegrated basin management is concerned with the interactions of physical, ecological, economic, and social systems as they affect the operation, planning, and policy making processes inherent in the management of land and water resources. Systems of integrated hydrological, chemical, biological, ecological, and socioeconomic models are typically used to assess the effects of proposed management alternatives on basin resources, or to manage basin resources in real time. Water is a common thread linking many of the components among these models. The ability to adequately simulate rainfall‐runoff processes and their interactions with processes related to other system components significantly affects the integrated system results. Model complexity and compatibility, data availability, and a number of error sources that include data, model parameters, and model structure, are major concerns in the use of integrated modeling systems. The effects of these error sources on the uncertainty in simulation results become even more complex in integrated system application in which output from one model is typically used as input to other models. The number and complexity of available integrated modeling systems represent a wide variety of approaches with different models, operational features, user interfaces, data formats, and analytical tools. For this review, integrated modeling systems have been characterized as using either a (i) dedicated‐system approach with a predefined set of models or (ii) modeling‐framework approach that typically enables the application of a user‐selected set of models. A number of available integrated systems within these two classifications are described and an example of application of a modular‐framework approach is presented.
Rainfall‐Runoff Modeling: Transfer Function Models
Authors: Young Peter C 
Published: April 2006

AbstractThis article discusses continuous and discrete‐time transfer function (TF) models within the context of the Data‐Based Mechanistic (DBM) modeling of hydrological systems. Although, at a superficial level, TF models simply provide a convenient and concise way of presenting differential or difference equations in an input‐output form, they are much more than this. In particular, they allow for the consideration of linear dynamic systems in simple algebraic terms and for their analysis within a dynamic systems and control context. This is useful in various ways, particularly where a higher order TF model is identified and estimated directly from hydrological data. Often, this data‐based model can then be decomposed into serial, parallel, and feedback connections of first‐order systems that can be interpreted in hydrologically meaningful terms, thereby facilitating the model's use in hydrological systems analysis. The article also shows that TF models can be considered in time‐variable and state‐dependent parameter (SDP) form, so allowing for them to describe nonstationary and nonlinear systems. And, since it is straightforward to consider all TF models in stochastic terms, they provide a powerful vehicle for uncertainty, forecasting, and risk analysis. The practical utility and power of DBM TF models is illustrated by two real hydrological examples.
Unsteady Flow
Authors: Graf Walter H , Altinakar Mustafa S 
Published: April 2006

AbstractFlow is unsteady, if the flow depth as well as other hydraulic parameters vary with time. An unsteady flow is usually also nonuniform. The one‐dimensional hydrodynamic equations, known are the equations of Saint‐Venant, are developed. The simplified equations of Saint‐Venant are used to treat the kinematic wave as well as the diffusive wave. The flood wave is also briefly discussed. Numerical solutions to unsteady flow will be treated in a subsequent chapter (seeNumerical Modeling of Unsteady Flows in Rivers).
Numerical Modeling of Unsteady Flows in Rivers
Authors: Krishnappan Bommanna G , Altinakar Mustafa S 
Published: April 2006

AbstractSolution methods to solve the unsteady flow equations are reviewed in this article. The basis of the method of characteristics is outlined. Some of the commonly used finite difference schemes are reviewed. A detailed description of an unsteady flow model called MOBED is given to highlight the various assumptions and simplifications that are involved in the development of an unsteady flow model. Testing of the model using a laboratory data set measured by Treske is described. Such a data set can serve as a benchmark data for the testing of unsteady flow models. Integral form of governing equations and their properties are introduced. High‐resolution conservative finite‐volume schemes for modeling flows with discontinuities are briefly discussed. Examples of numerical solutions using a robust one‐dimensional upwind finite‐volume code are presented.
Debris Flow
Authors: Armanini Aronne , Fraccarollo Luigi , Larcher Michele 
Published: April 2006

AbstractThe principal features of debris flow are described. One section is devoted to debris‐flow triggering, accounting for the geomechanical criteria by Takahashi (1978) and for most recent hydrological distributed models. In a second section, the rheology of debris flows is described: the theory of dispersive stresses by Bagnold, the kinetic theories of dense gases, and some recent experimental observations about debris flows in equilibrium. A section is devoted to mathematical models and the final section discusses debris flows countermeasures.
Groundwater as an Element in the Hydrological Cycle
Authors: Alley William M , La Baugh James W , Reilly Thomas E 
Published: April 2006

AbstractGroundwater commonly is portrayed in diagrams of the hydrological cycle as a single pool of water with simple transfers of water to and from the land surface, oceans, and atmosphere. In reality, groundwater is an integral part of a complex hydrological cycle that involves the continuous movement of water on Earth. We begin with a global perspective on the importance of groundwater in the hydrological cycle and then address the importance of understanding the dynamics of groundwater‐flow systems. We next turn our attention to groundwater budgets and the effects of humans and climate on these budgets. The final section is devoted to a discussion of interactions between groundwater and surface water, and we highlight the importance of these interactions in the hydrological cycle.
Characterization of Porous and Fractured Media
Authors: Renard Philippe , Gómez‐Hernández Jaime , Ezzedine Souheil 
Published: April 2006

Abstract
The characterization of porous or fractured media is a site, scale, and project‐specific process aiming at a quantitative description of the geometry and properties of the geological structures controlling groundwater flow and solute transport. The characterization process involves four main steps (i) the definition of the domain and the goals of the characterization; (ii) the collection and analysis of field observations allowing the construction of a geometrical model; (iii) the collection and analysis of field measurements allowing to construct a property model; and (iv) the collection and analysis of field data relative to the state of the system and their integration within the geometrical and property models (inverse problem). When data are sufficient and structures are relatively well known, deterministic techniques of interpolation can be successfully applied to construct the geometric or the parameter models. However, because of the lack of sufficient data, stochastic models are often employed to characterize the heterogeneity that usually exists; such models also facilitate the quantification of the uncertainty in model predictions. Without describing the details of every technique, this article provides an overview of the tools most often used for the characterization of porous or fractured aquifers.
Inverse Methods for Parameter Estimations
Authors: Sun Ne‐Zheng , Sun Alexander Y 
Published: April 2006

AbstractEstimation of various flow and mass transport parameters can be seen as the inverse problem of groundwater modeling. In this article, current methodologies for parameter estimation are classified according to whether they consider the errors in observation data, in parameter structure, and in model applications. The structures of hydraulic parameters are usually very complex and unknown. This article gives an overview on adaptive parameterization methods for simultaneously identifying the parameter values, the complexity level, and the pattern of parameter structure. Methods for model reliability analysis are described. Finally, a generalized inverse problem is introduced that can find a representative parameter for a given model application.
Hydrodynamics of Groundwater
Authors: Stauffer Fritz 
Published: April 2006

Abstract
The mathematical formulation of problems of flow in aquifers is usually based on a formulation of the fluid mass balance, which has to be fulfilled at any location in the domain under consideration. A knowledge of the fluid mass flux through the saturated aquifer material, or the motion equation, is required. The resulting partial differential equation can be solved for a chosen flow domain, given parameters, and initial and boundary conditions. The solution results in the steady state or transient field of the piezometric head, from which the flux and the velocity fields may be expressed.
Modeling Solute Transport Phenomena
Authors: Bear Jacob 
Published: April 2006

Abstract

The article presents the conceptual and well‐posed mathematical models that describe the transport of solutes, or chemical species, in porous media, as encountered when considering the transport of dissolved salts and contaminants in aquifers. The various modes of transport: advection dispersion and diffusion are discussed and incorporated in the models. Solute sources are also incorporated in the models, including adsorption and an introduction to reactive transport. We shall emphasize that the fluid's velocity, and in unsaturated flow, also the fluid's saturation is required as input information to any solute transport problem. However, the model of flow problem that provides this information is discussed in
Hydrodynamics of Groundwater
. Unsaturated flow models are discussed in
Unsaturated Zone Flow Processes
. The case of solute transport with variable density is not included, as it is presented in
Sea Water Intrusion Into Coastal Aquifers
. More about chemical and biological reactions is presented in
Groundwater Pollution and Remediation
.
Groundwater Pollution and Remediation
Authors: McNab Walt , Hoffman Fred , Dooher Brendan 
Published: April 2006

Abstract
Contamination of groundwater resources by a variety of anthropogenic pollutants from both point and non‐point sources represents a key global environmental problem. Contaminant species of concern include solvents, fuel hydrocarbons, heavy metals, pesticides, nitrate, and radionuclides. Groundwater contamination reflects local physical hydrogeological considerations but also the inherent properties of the contaminants. An understanding of the factors controlling contaminant behavior in the subsurface is a necessary prerequisite to exploring possible remedial solutions. These factors include the partitioning processes that govern the distribution of contaminant species between the aqueous phase, the solid phase (including adsorption onto soil particle surfaces), the gas phase, and, in some cases, nonaqueous phase liquids. Chemical and biological transformation processes also impact the behavior of different types of subsurface contaminants. The designs of passive and active groundwater remediation approaches often reflect consideration of one or more of these factors; however, the efficacy of most methods is often most closely dependent upon the physical characteristics of the subsurface environment, such as the distribution of hydraulic conductivity.