Compendium of Watershed-scale Models for TMDL Development PDF Download

Author:
Publisher:
ISBN:
Category : Water
Languages : en
Pages : 100

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Author: L. Shoemaker
Publisher:
ISBN: 9780756728243
Category : Nature
Languages : en
Pages : 227

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Broadens the review of models and techniques from solely watershed loading models to include receiving water models and ecological assess. techniques and models. It summarizes avail. techniques and models that assess and predict physical, chemical, and biol. conditions in waterbodies. Includes info. regarding: a wide range of watershed-scale loading models; field-scale loading models; receiving water models, including eutrophication/water quality models, toxics models, and hydrodynamic models; integrated modeling systems that, for example, link watershed-scale loading with receiving water processes; and ecological techniques and models that can be used to assess &/or predict the status of habitat, single species, or biol. community.

Author: Charles Wayne Downer
Publisher:
ISBN:
Category : Watersheds
Languages : en
Pages : 11

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Author: National Research Council
Publisher: National Academies Press
ISBN: 0309075793
Category : Political Science
Languages : en
Pages : 242

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Over the last 30 years, water quality management in the United States has been driven by the control of point sources of pollution and the use of effluent-based water quality standards. Under this paradigm, the quality of the nation's lakes, rivers, reservoirs, groundwater, and coastal waters has generally improved as wastewater treatment plants and industrial dischargers (point sources) have responded to regulations promulgated under authority of the 1972 Clean Water Act. These regulations have required dischargers to comply with effluent-based standards for criteria pollutants, as specified in National Pollutant Discharge Elimination System (NPDES) permits issued by the states and approved by the U.S. Environmental Protection Agency (EPA). Although successful, the NPDES program has not achieved the nation's water quality goals of "fishable and swimmable" waters largely because discharges from other unregulated nonpoint sources of pollution have not been as successfully controlled. Today, pollutants such as nutrients and sediment, which are often associated with nonpoint sources and were not considered criteria pollutants in the Clean Water Act, are jeopardizing water quality, as are habitat destruction, changes in flow regimes, and introduction of exotic species. This array of challenges has shifted the focus of water quality management from effluent-based to ambient- based water quality standards. Given the most recent lists of impaired waters submitted to EPA, there are about 21,000 polluted river segments, lakes, and estuaries making up over 300,000 river and shore miles and 5 million lake acres. The number of TMDLs required for these impaired waters is greater than 40,000. Under the 1992 EPA guidance or the terms of lawsuit settlements, most states are required to meet an 8- to 13-year deadline for completion of TMDLs. Budget requirements for the program are staggering as well, with most states claiming that they do not have the personnel and financial resources necessary to assess the condition of their waters, to list waters on 303d, and to develop TMDLs. A March 2000 report of the General Accounting Office (GAO) highlighted the pervasive lack of data at the state level available to set water quality standards, to determine what waters are impaired, and to develop TMDLs. This report represents the consensus opinion of the eight-member NRC committee assembled to complete this task. The committee met three times during a three-month period and heard the testimony of over 40 interested organizations and stakeholder groups. The NRC committee feels that the data and science have progressed sufficiently over the past 35 years to support the nation's return to ambient-based water quality management. Given reasonable expectations for data availability and the inevitable limits on our conceptual understanding of complex systems, statements about the science behind water quality management must be made with acknowledgment of uncertainties. This report explains that there are creative ways to accommodate this uncertainty while moving forward in addressing the nation's water quality challenges.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Development of total maximum daily loads (TMDLs) for critical pollutants in impaired watersheds is becoming a standard approach in environmental management. This requires the identification of future loading of contributing pollutants, and the development of a plan to allocate the necessary reductions among the point and nonpoint sources in the watershed to achieve this loading. To support water quality model-based TMDL development, US EPA has released the modeling framework BASINS-Better Assessment Science Integrating Point and Nonpoint Source, which incorporates several watershed water quality models within a GIS-based data management system. Current capabilities of BASINS enable simulation of watershed water quality associated with a TMDL, thus supporting TMDL development via a trial-and-error approach. The limitations of the trial-and-error approach are addressed via systematic search procedures implemented within the Water Quality Management Decision Support System (WQMDSS) that is designed to aid stakeholders and decision-makers efficiently identify TMDLs. The focus of the research presented in this paper is to demonstrate the applicability of WQMDSS in developing TMDLs for a realistic illustrative case study. Using the data for the Suwanee Creek Watershed in Georgia, which underwent a recent TMDL study, a series of illustrative scenarios are examined to consider varying target total suspended solids (TSS) loading rates, as well as different instream water quality parameters. The instream water quality is estimated using a calibrated HSPF model. Future land use development plans, with and without consideration of riparian buffer strips for nonpoint source control, to meet instream water quality goals are identified. Through this illustrative study, a range of uses of WQMDSS in watershed-scale TMDL development is demonstrated.

Author: American Society of Civil Engineers. TMDL Analysis and Modeling Task Committee
Publisher: Asce American Society of Civil Engineers Ewri
ISBN: 9780784414712
Category : Water
Languages : en
Pages : 0

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This report reviews more than 35 TMDL models and procedures for estimating the maximum amount of a pollutant that a water body can receive and still meet applicable water quality standards.

Author: Robert Nunoo
Publisher:
ISBN:
Category : Hydrologic models
Languages : en
Pages : 139

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Book Description
Watershed models are used to represent the physical, chemical, and biological mechanisms that determine the fate and transport of pollutants in waterbodies (Daniel 2011). These models, in general, are used for exploratory, planning, and regulatory purposes (Harmel and others 2014). Watershed models have numerous applications; one such use is the development of total maximum daily load (TMDL). TMDL is the amount of pollution a waterbody can receive without becoming impaired. Because of the challenge of uncertainty associated with models and the TMDL development process, the United States Clean Water Act Section 303 (d)(1)(c) requires that a margin of safety (MOS) be specified to account for uncertainty in TMDLs. The question of how MOS is estimated in TMDL was identified as a problem by the National Research Council (NRC 2001). Since the identification of the problem about two decades ago, there have been very few inventories or audits of approved TMDL studies.This study describes a natural language processing and machine learning aided review of the MOS in approved TMDLs from 2002 to 2016. The study determined whether the MOS values incorporated followed a pattern and examined whether there exist a relationship between MOS values and some ecological conditions. Relatively few TMDLs were based on some form of calculation to estimate explicit MOS values; these TMDLs constituted only 16% of the reviewed sample. The remaining 84% used conventional values, but few of those studies provided reasons for their selected values. A statistical assessment of those MOS values revealed that the MOS depended on States (location of waterbody), USEPA regions, waterbody type, designated water use, TMDL model used, and dataavailability. The findings indicate that few TMDL developers are following the National Research Council’s suggestions of using a rigorous uncertainty estimation approach for rational choices for the MOS. An adaptive approach based on Bayes-Discrepancy was proposed for estimating an MOS for a TMDL. The approach is based on the Bayesian hierarchical framework of estimating uncertainty associated with watershed models. With this approach, TMDL developers can communicate the effects of their watershed model. The approach was applied to a Ferson Creek model of the Fox River watershed to access variability and uncertainty in the model results, and also estimate possible MOS values for two monitoring stations in the watershed. Results suggest that an MOS of 0.04 mg/L could lead to a 0.1 probability of violating the water quality standard for an underpredicting model. The Bayes-discrepancy estimation method will enable TMDL developers and watershed managers to strike a balance between implementation options and water quality concerns.

Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309679702
Category : Science
Languages : en
Pages : 423

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New York City's municipal water supply system provides about 1 billion gallons of drinking water a day to over 8.5 million people in New York City and about 1 million people living in nearby Westchester, Putnam, Ulster, and Orange counties. The combined water supply system includes 19 reservoirs and three controlled lakes with a total storage capacity of approximately 580 billion gallons. The city's Watershed Protection Program is intended to maintain and enhance the high quality of these surface water sources. Review of the New York City Watershed Protection Program assesses the efficacy and future of New York City's watershed management activities. The report identifies program areas that may require future change or action, including continued efforts to address turbidity and responding to changes in reservoir water quality as a result of climate change.

Author:
Publisher:
ISBN:
Category : Pathogenic microorganisms
Languages : en
Pages : 140

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Author: Vijay P. Singh
Publisher: CRC Press
ISBN: 1420037439
Category : Science
Languages : en
Pages : 678

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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