Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Surface And Subsurface Flow And Contaminant Transport Modeling In Lower Altamaha Watershed PDF full book. Access full book title Surface And Subsurface Flow And Contaminant Transport Modeling In Lower Altamaha Watershed.
| Author | : Orhan Gunduz |
| Publisher | : |
| Total Pages | : 270 |
| Release | : 2004 |
| Genre | : Groundwater |
| ISBN | : |
| Author | : Orhan Gunduz |
| Publisher | : |
| Total Pages | : 934 |
| Release | : 2004 |
| Genre | : Hydrologic models |
| ISBN | : |
A hybrid surface/subsurface flow and transport model is developed that blends distributed parameter models with simpler lumped parameter models. The hybrid model solves the channel flow and saturated groundwater flow domains in continuous time using fully distributed physically-based formulations. This system is supplemented with the overland flow and unsaturated groundwater flow that uses lumped parameter descriptions in discrete time. In the proposed model, a one-dimensional channel flow model is dynamically coupled with a two-dimensional vertically-averaged groundwater flow model along the river bed. As an alternative to the commonly applied iterative solution technique, a so-called simultaneous solution procedure is developed to provide a better understanding to the coupled flow problem. This new methodology is based on the principle of solving the two flow domains within a single matrix structure in a simultaneous manner. In addition to the flow model, a coupled contaminant transport model is also developed to simulate the migration of contaminants between surface and subsurface domains. The contaminant transport model dynamically couples a one-dimensional channel transport model with a two-dimensional vertically-averaged groundwater transport model. The coupling is performed at the river bed interface via advective and dispersive transport mechanisms. A modified extension of the proposed simultaneous solution procedure is also implemented to solve the coupled contaminant transport problem. The dynamic coupling provides the much needed understanding for the continuity of contaminants in strongly interacting surface/subsurface systems such as a river and an unconfined aquifer. The coupled flow and transport models are applied to the lower Altamaha watershed in southern Georgia. The flow model is used to perform simulations of hydrologic and hydraulic conditions along the river and in the dynamically linked surfacial aquifer. The model predicted the flood patterns including the magnitude of peaks and their arrival times with accuracy. Under the given flow conditions, the transport model is then implemented to test alternative contaminant transport patterns both in the river and within the aquifer. It has been found that the channel network would serve as a conduit for rapid transport of contaminants within the aquifer to large distances in small time frames.
| Author | : Claudia Valenzuela |
| Publisher | : |
| Total Pages | : 94 |
| Release | : 2004 |
| Genre | : Hydrology |
| ISBN | : |
| Author | : Zhiguo He |
| Publisher | : |
| Total Pages | : 392 |
| Release | : 2007 |
| Genre | : |
| ISBN | : |
Hydro-system within a watershed includes many environmental processes, such as rainfall, runoff, groundwater flow, infiltration, evapotranspiration, recharge, upland erosion, sediment transport, and contaminant transport. In order to investigate these processes and evaluate their effects on water environments, numerical models have been recognized as an increasingly efficient and effective tool. Due to the natural intrinsic connections between surface and subsurface waters, modeling of flow, upland soil erosion, and contaminant transport should be considered as an integrated system. This dissertation has developed a physically-based integrated numerical model for flow, sediment, and contaminant transport in the surface-subsurface system. In this model, the surface flow is calculated using a depth-averaged 2-D diffusion wave model, and the variably saturated subsurface flow is computed using the 3-D mixed-form Richards equation. Interactions between surface and subsurface flows are considered using the continuity conditions of the pressure head and exchange flux at the ground surface. A general form of the surface flow equation based on the diffusion wave approximation is developed, which is intrinsically coupled with the variably saturated subsurface flow equation. The upland soil erosion and transport model employs the concept of nonequilibrium that considers both erosion and deposition. The model simulates nonuniform total-load sediment transport, with detachments from rainsplash and/or hydraulic erosion driven by overland flow. Contaminant transports in both surface and subsurface domains are described using advection-diffusion equations. The model considers the sediment sorption and desorption of the contaminant, as well as contaminant exchanges between surface and subsurface due to infiltration, diffusion, and bed change. The integrated numerical model is evaluated by simulating several published laboratory- and field-scale experiments. It is further applied to compute flow discharge, sediment and pesticide concentration during storm events in the Deep Hollow Lake watershed, Mississippi. The sensitivity analysis of the model is also performed using different values for several model parameters. The results have shown that the integrated model framework is capable of simulating the rainfall-runoff related hydrological processes in natural surface-subsurface systems.
| Author | : George Yeh |
| Publisher | : |
| Total Pages | : 369 |
| Release | : 1998 |
| Genre | : Groundwater |
| ISBN | : |
This report presents the development of a numerical model simulating water flow and contaminant and sediment transport in watershed systems of one-dimensional river/stream network, two-dimensional overland regime, and three-dimensional sub surface media. The model is composed of two modules: flow and transport. Three options are provided in modeling the flow module in river/stream network and overland regime: the kinematic wave approach, diffusion wave approach, and dynamic wave approach. The kinematic and diffusion wave approaches are known to be numerically robust in terms of numerical convergency and stability; i.e., they can generate convergent and stable simulations over a wide range of ground surface slopes in the entire watershed. The question is the accuracy of these simulations. The kinematic wave approach usually produces accurate solutions only over the region of steep slopes. The diffusion wave approach normally gives accurate solutions over the region of mild to steep slopes. However, neither approach has the ability to yield accurate solutions over the region of small slopes, in which the inertial forces are no longer negligible compared to the gravitational forces. The kinematic wave approach cannot address the problems of backwater effects. On the other hand, a dynamic wave approach, having included all forces, can theoretically have the potential to generate accurate simulations over all ranges of slopes in a watershed. The subsurface flow is described by Richard's equation where water flow through saturated-unsaturated porous media is accounted for.
| Author | : Vijay P. Singh |
| Publisher | : CRC Press |
| Total Pages | : 678 |
| Release | : 2010-09-28 |
| Genre | : Science |
| ISBN | : 1420037439 |
Watershed modeling is at the heart of modern hydrology, supplying rich information that is vital to addressing resource planning, environmental, and social problems. Even in light of this important role, many books relegate the subject to a single chapter while books devoted to modeling focus only on a specific area of application. Recognizing the
| Author | : Orhan Gunduz |
| Publisher | : |
| Total Pages | : 106 |
| Release | : 2003 |
| Genre | : Groundwater |
| ISBN | : |
| Author | : |
| Publisher | : |
| Total Pages | : 267 |
| Release | : 1998 |
| Genre | : |
| ISBN | : |
This report presents the development of a numerical model simulating water flow and contaminant and sediment transport in watershed systems of one-dimensional river/stream network, two-dimensional overland regime, and three-dimensional sub surface media. The model is composed of two modules: flow and transport. Three options are provided in modeling the flow module in river/stream network and overland regime: the kinematic wave approach, diffusion wave approach, and dynamic wave approach. The kinematic and diffusion wave approaches are known to be numerically robust in terms of numerical convergency and stability; i.e., they can generate convergent and stable simulations over a wide range of ground surface slopes in the entire watershed. The question is the accuracy of these simulations. The kinematic wave approach usually produces accurate solutions only over the region of steep slopes. The diffusion wave approach normally gives accurate solutions over the region of mild to steep slopes. However, neither approach has the ability to yield accurate solutions over the region of small slopes, in which the inertial forces are no longer negligible compared to the gravitational forces. The kinematic wave approach cannot address the problems of backwater effects. On the other hand, a dynamic wave approach, having included all forces, can theoretically have the potential to generate accurate simulations over all ranges of slopes in a watershed. The subsurface flow is described by Richard's equation where water flow through saturated-unsaturated porous media is accounted for.
| Author | : Karl Bandilla |
| Publisher | : |
| Total Pages | : 114 |
| Release | : 2009 |
| Genre | : |
| ISBN | : |
This work introduces a combination of the vertically integrated Analytic Element and deterministic Streamline methods for watershed-scale groundwater flow and contaminant transport modeling. This new method combines the Analytic Element Method's ability of modeling large spatial domains while preserving stream-scale details, with the conceptional elegance of the Streamline method. Both methods allow for parallel processing in order to reduce model run-times. The intended use of this new method is the study of non-point source contaminant transport on the watershed scale (e.g., nutrient loading to surface water from agricultural fields). A new iterative Analytic Element Method algorithm is devised for solving 2D steady-state groundwater flow models containing large numbers of head-specified elements (e.g. rivers and lakes).^The new algorithm improves convergence of models containing head-specified elements by explicitly computing fluxes of all such features at the start of each iteration. The new algorithm alsoenables the use of efficient parallel processing on distributed-memory super-computers. The combination of parallel processing and reduced number of iterations significantly extends the size and complexity of problems that can be modeled using the Analytic Element Method. The vertically integrated Analytic Element Method flow solution is used to construct three-dimensional particle tracks that define the geometry of the Streamline Method by approximating vertical flow. The inherently parallel nature of the algorithm supports the development of reactive transport models for spatial domains much larger than current grid-based methods.^The applicability of the new approach is verified for cases with negligible transverse dispersion through comparisons to analytic solutions and existing numerical solutions, and parallel performance is demonstrated through a realistic test problem based on the regional-scale transport of agricultural contaminants from spatially distributed sources.
| Author | : National Research Council |
| Publisher | : National Academies Press |
| Total Pages | : 320 |
| Release | : 1990-02-01 |
| Genre | : Science |
| ISBN | : 0309039932 |
The discovery of toxic pollution at Love Canal brought ground water contamination to the forefront of public attention. Since then, ground water science and modeling have become increasingly important in evaluating contamination, setting regulations, and resolving liability issues in court. A clearly written explanation of ground water processes and modeling, Ground Water Models focuses on the practical aspects of model application. It: examines the role of models in regulation, litigation, and policy development; explains ground water processes and describes specific applications for models; presents emerging technologies; and offers specific recommendations for better use of ground water science in policy formation.
