Browsing by Author "Veith, Tamie L."

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    Agricultural BMP Placement for Cost-effective Pollution Control at the Watershed Level
    Veith, Tamie L. (Virginia Tech, 2002-02-11)
    The overall goal of this research was to increase, relative to targeting recommendations, the cost-effectiveness of pollution reduction measures within a watershed. The goal was met through development of an optimization procedure for best management practice (BMP) placement at the watershed level. The procedure combines an optimization component, written in the C++ language, with spatially variable nonpoint source (NPS) prediction and economic analysis components, written in the ArcView geographic information system scripting language. The procedure is modular in design, allowing modifications or enhancements to the components while maintaining the overall theory. The optimization component uses a genetic algorithm to optimize a lexicographic multi-objective function of pollution reduction and cost increase. The procedure first maximizes pollution reduction to meet a specified goal, or maximum allowable load, and then minimizes cost increase. For the NPS component, a sediment delivery technique was developed and combined with the Universal Soil Loss Equation to predict average annual sediment yield at the watershed outlet. Although this evaluation considered only erosion, the NPS pollutant fitness score allows for evaluation of multiple pollutants, based on prioritization of each pollutant. The economic component considers farm-level public and private costs, accounting for crop productivity levels by soil and for enterprise budgets by field. The economic fitness score assigns higher fitness scores to scenarios in which costs decrease or are distributed more evenly across farms. Additionally, the economic score considers the amounts of cropland, hay, and pasture needed to meet feed and manure/poultry litter spreading requirements. Application to two watersheds demonstrated that the procedure optimized BMP placement, locating scenarios more cost-effective than a targeting strategy solution. The optimization procedure identified solutions with lower costs than the targeting strategy solution for the same level of pollution reduction. The benefit to cost ratio, including use of the procedure and implementation of resulting solutions, was demonstrated to be greater for the optimization procedure than for the targeting strategy. The optimization procedure identifies multiple near optimal solutions. Additionally, the procedure creates and evaluates scenarios in a repeated fashion without requiring human interaction. Thus, more scenarios can be evaluated than are feasible to evaluate manually.
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    The Chesapeake Bay program modeling system: Overview and recommendations for future development
    Hood, Raleigh R.; Shenk, Gary W.; Dixon, Rachel L.; Smith, Sean M. C.; Ball, William P.; Bash, Jesse O.; Batiuk, Rich; Boomer, Kathy; Brady, Damian C.; Cerco, Carl; Claggett, Peter; de Mutsert, Kim; Easton, Zachary M.; Elmore, Andrew J.; Friedrichs, Marjorie A. M.; Harris, Lora A.; Ihde, Thomas F.; Lacher, Lara; Li, Li; Linker, Lewis C.; Miller, Andrew; Moriarty, Julia; Noe, Gregory B.; Onyullo, George E.; Rose, Kenneth; Skalak, Katie; Tian, Richard; Veith, Tamie L.; Wainger, Lisa A.; Weller, Donald; Zhang, Yinglong Joseph (2021-09-15)
    The Chesapeake Bay is the largest, most productive, and most biologically diverse estuary in the continental United States providing crucial habitat and natural resources for culturally and economically important species. Pressures from human population growth and associated development and agricultural intensification have led to excessive nutrient and sediment inputs entering the Bay, negatively affecting the health of the Bay ecosystem and the economic services it provides. The Chesapeake Bay Program (CBP) is a unique program formally created in 1983 as a multi-stakeholder partnership to guide and foster restoration of the Chesapeake Bay and its watershed. Since its inception, the CBP Partnership has been developing, updating, and applying a complex linked modeling system of watershed, airshed, and estuary models as a planning tool to inform strategic management decisions and Bay restoration efforts. This paper provides a description of the 2017 CBP Modeling System and the higher trophic level models developed by the NOAA Chesapeake Bay Office, along with specific recommendations that emerged from a 2018 workshop designed to inform future model development. Recom-mendations highlight the need for simulation of watershed inputs, conditions, processes, and practices at higher resolution to provide improved information to guide local nutrient and sediment management plans. More explicit and extensive modeling of connectivity between watershed landforms and estuary sub-areas, estuarine hydrodynamics, watershed and estuarine water quality, the estuarine-watershed socioecological system, and living resources will be important to broaden and improve characterization of responses to targeted nutrient and sediment load reductions. Finally, the value and importance of maintaining effective collaborations among jurisdictional managers, scientists, modelers, support staff, and stakeholder communities is emphasized. An open collaborative and transparent process has been a key element of successes to date and is vitally important as the CBP Partnership moves forward with modeling system improvements that help stakeholders evolve new knowledge, improve management strategies, and better communicate outcomes.
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    Cost-effective BMP placement: Optimization versus targeting
    Veith, Tamie L.; Wolfe, Mary Leigh; Heatwole, Conrad D. (American Society of Agricultural and Biological Engineers, 2004)
    Cost-effectiveness of nonpoint-source pollution reduction programs in an agricultural watershed depends on the selection and placement of control measures within the watershed. Locations for best management practices (BMPs) are commonly identified through targeting strategies that define locations for BMP implementation based on specific criteria uniformly applied across the watershed. The goal of this research was to determine if cost-effectiveness of BMP scenarios could be improved through optimization rather than targeting. The optimization procedure uses a genetic algorithm (GA) to search for the combination of site-specific practices that meets pollution reduction requirements, and then continues searching for the BMP combination that minimizes cost. Population size, replacement level, crossover, and mutation parameters for the GA were varied to determine the most efficient combination of values. A baseline scenario, a targeting strategy, and three optimization plans were applied to a 1014 ha agricultural watershed in Virginia. All three optimization plans identified BMP placement scenarios having lower cost than the targeting strategy solution for equivalent sediment reduction. The targeting strategy reduced average annual sediment loss compared to the baseline at a cost of $42 per kg sediment reduction/ha. The optimization plan with the same BMP choices achieved the same sediment reduction at a cost of $36 per kg/ha. Allocation of BMPs varied among optimization solutions, a possibility not available to the targeting strategy. In particular the optimization solutions placed BMPs on several stream-edge fields that did not receive BMPs in the targeting strategy.
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    Evaluation of Phosphorus Site Assessment Tools: Lessons from the USA
    Sharpley, Andrew; Kleinman, Peter J. A.; Baffaut, Claire; Beegle, Doug; Bolster, Carl; Collick, Amy; Easton, Zachary M.; Lory, John; Nelson, Nathan; Osmond, Deanna; Radcliffe, David E.; Veith, Tamie L.; Weld, Jennifer (2017-11)
    Critical source area identification through phosphorus (P) site assessment is a fundamental part of modern nutrient management planning in the United States, yet there has been only sparse testing of the many versions of the P Index that now exist. Each P site assessment tool was developed to be applicable across a range of field conditions found in a given geographic area, making evaluation extremely difficult. In general, evaluation with in-field monitoring data has been limited, focusing primarily on corroborating manure and fertilizer "source" factors. Thus, a multiregional effort (Chesapeake Bay, Heartland, and Southern States) was undertaken to evaluate P Indices using a combination of limited field data, as well as output from simulation models (i.e., Agricultural Policy Environmental eXtender, Annual P Loss Estimator, Soil and Water Assessment Tool [SWAT], and Texas Best Management Practice Evaluation Tool [TBET]) to compare against P Index ratings. These comparisons show promise for advancing the weighting and formulation of qualitative P Index components but require careful vetting of the simulation models. Differences among regional conclusions highlight model strengths and weaknesses. For example, the Southern States region found that, although models could simulate the effects of nutrient management on P runoff, they often more accurately predicted hydrology than total P loads. Furthermore, SWAT and TBET overpredicted particulate P and underpredicted dissolved P, resulting in correct total P predictions but for the wrong reasons. Experience in the United States supports expanded regional approaches to P site assessment, assuming closely coordinated efforts that engage science, policy, and implementation communities, but limited scientific validity exists for uniform national P site assessment tools at the present time.
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    Improved Simulation of Edaphic and Manure Phosphorus Loss in SWAT
    Collick, Amy S.; Veith, Tamie L.; Fuka, Daniel R.; Kleinman, Peter J. A.; Buda, Anthony R.; Weld, Jennifer L.; Bryant, Ray B.; Vadas, Peter A.; White, Mike J.; Harmel, R. Daren; Easton, Zachary M. (2016-07)
    Watershed models such as the Soil Water Assessment Tool (SWAT) and the Agricultural Policy Environmental EXtender (APEX) are widely used to assess the fate and transport of agricultural nutrient management practices on soluble and particulate phosphorus (P) loss in runoff. Soil P-cycling routines used in SWAT2012 revision 586, however, do not simulate the short-term effects of applying a concentrated source of soluble P, such as manure, to the soil surface where it is most vulnerable to runoff. We added a new set of soil P routines to SWAT2012 revision 586 to simulate surface-applied manure at field and subwatershed scales within Mahantango Creek watershed in south-central Pennsylvania. We corroborated the new P routines and standard P routines in two versions of SWAT (conventional SWAT, and a topographically driven variation called TopoSWAT) for a total of four modeling "treatments". All modeling treatments included 5 yr of measured data under field-specific, historical management information. Short-term "wash off" processes resulting from precipitation immediately following surface application of manures were captured with the new P routine whereas the standard routines resulted in losses regardless of manure application. The new routines improved sensitivity to key factors in nutrient management (i.e., timing, rate, method, and form of P application). Only the new P routines indicated decreases in soluble P losses for dairy manure applications at 1, 5, and 10 d before a storm event. The new P routines also resulted in more variable P losses when applying manure versus commercial fertilizer and represented increases in total P losses, as compared with standard P routines, with rate increases in dairy manure application (56,000 to 84,000 L ha(-1)). The new P routines exhibited greater than 50% variation among proportions of organic, particulate, and soluble P corresponding to spreading method. In contrast, proportions of P forms under the standard P routines varied less than 20%. Results suggest similar revisions to other agroecosystem watershed models would be appropriate.
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    Netsim: A Java(TM) -Based WWW Simulation Package
    Veith, Tamie L. (Virginia Tech, 1997-04-29)
    Use of the World Wide Web (WWW) for transfer of information and ideas is increasingly popular. Java, a programming language for the WWW, provides a simple method of distributing platform-independent, executable programs over the WWW. Such programs allow the expansion of WWW-based computational and analytical tools that support and enhance the existing WWW environment. However, a WWW-based, generalized simulation package is not yet available. Current literature motivates development of a general, WWW-based simulation package with maximum user interactivity and cross-platform capabilities. Advantages of such a package are discussed and explored in three potential applications. Main advantages are wide availability, controlled access, efficient maintenance, and increased integration. Disadvantages, such as variable download times, are also discussed. Netsim, a general, WWW-based simulation package written entirely in Java, is developed and demonstrated. Netsim provides complete model creation and modification capabilities along with graphical animation and data output. Netsim uses the event graph paradigm and object-oriented programming. Java, event graphs and objectoriented programming are discussed briefly. The Java random number generator is verified for uniformity and independence. Netsim is compared to SIGMA, a non-Internet simulation package, using a standard M/M/1 queueing model. Comparison issues and results are discussed. Additionally, tested through hand-tracing for coding validity, Netsim performs as theory prescribes. Netsim documentation and user’s manual are included. Netsim allows expandability for complex modeling and integration with other Java-based programs, such as graphing and analysis packages. Current Netsim limitations and potential customization and expansion issues are explored. Future work in WWW-based simulation is suggested.
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    The Promise, Practice, and State of Planning Tools to Assess Site Vulnerability to Runoff Phosphorus Loss
    Kleinman, P. J. A.; Sharpley, A. N.; Buda, A. R.; Easton, Zachary M.; Lory, J. A.; Osmond, D. L.; Radcliffe, David E.; Nelson, N. O.; Veith, Tamie L.; Doody, D. G. (2017-11)
    Over the past 20 yr, there has been a proliferation of phosphorus (P) site assessment tools for nutrient management planning, particularly in the United States. The 19 papers that make up this special section on P site assessment include decision support tools ranging from the P Index to fate-and-transport models to weather-forecast-based risk calculators. All require objective evaluation to ensure that they are effective in achieving intended benefits to protecting water quality. In the United States, efforts have been underway to compare, evaluate, and advance an array of P site assessment tools. Efforts to corroborate their performance using water quality monitoring data confirms previously documented discrepancies between different P site assessment tools but also highlights a surprisingly strong performance of many versions of the P Index as a predictor of water quality. At the same time, fate-and-transport models, often considered to be superior in their prediction of hydrology and water quality due to their complexity, reveal limitations when applied to site assessment. Indeed, one consistent theme from recent experience is the need to calibrate highly parameterized models. As P site assessment evolves, so too do routines representing important aspects of P cycling and transport. New classes of P site assessment tools are an opportunity to move P site assessment from general, strategic goals to web-based tools supporting daily, operational decisions.