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Browsing by Author "Aguilar, Marcus F."

Now showing 1 - 4 of 4
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    Analysis, Modeling, and Forecasting Of Urban Flooding
    Brendel, Conrad (Virginia Tech, 2020-04-08)
    As the world becomes more urbanized and heavy precipitation events increase in frequency and intensity, urban flooding is an emerging concern. Urban flooding is caused when heavy rainfall collects on the landscape, exceeding the capacity of drainage systems to effectively convey runoff. Unlike riverine and coastal flooding, urban flooding occurs frequently, and its risks and impacts are not restricted to areas within floodplains or near bodies of water. The objective of this dissertation is to improve our understanding of urban flooding and our capability to predict it through the development of tools and knowledge to assist with its analysis, modeling, and forecasting. To do this, three research objectives were fulfilled. First, the Stream Hydrology And Rainfall Knowledge System (SHARKS) app was developed to improve upon existing real-time hydrologic and meteorological data retrieval/visualization platforms through the integration of analysis tools to study the hydrologic processes influencing urban flooding. Next, the ability to simulate the hydrologic response of urban watersheds with large storm sewer networks was compared between the fully distributed Gridded Surface/Subsurface Hydrologic Analysis (GSSHA) model and the semi-distributed Storm Water Management Model (SWMM). Finally, the Probabilistic Urban Flash Flood Information Nexus (PUFFIN) application was created to help users evaluate the probability of urban flash flooding and to identify specific infrastructure components at risk through the integration of high-resolution quantitative precipitation forecasting, ensemble forecasting, and hydrologic and hydraulic modeling. The outcomes of this dissertation provide municipalities with tools and knowledge to assist them throughout the process of developing solutions to their site-specific urban flooding issues. Specifically, tools are provided to rapidly analyze and respond to rainfall and streamflow/depth information during intense rain events and to perform retrospective analysis of long-term hydrological processes. Evaluations are included to help guide the selection of hydrologic and hydraulic models for modeling urban flooding, and a new proactive paradigm of probabilistic flash flood guidance for urban areas is introduced. Finally, several potential directions for future work are recommended.
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    Leveraging Technology to Add Value to a Phase II NPDES Permit
    Aguilar, Marcus F. (Virginia Tech, 2013-06-03)
    In 1999, Phase II of the National Pollutant Discharge Elimination System engaged operators of small Municipal Separate Storm Sewer Systems (MS4) in the control of runoff from urban areas.  The complex task of urban runoff mitigation has been investigated for several decades, resulting in a large variety of available computing and measurement tools for urban stormwater management.  Unfortunately, these tools may not be available to the MS4 operator in a format that is both concise, and directly applicable.  To address this need, this thesis recommends stormwater model creation and refinement strategies for Phase II MS4s using GIS and Python scripting.  Further recommendations on using a popular discharge measurement technique for model calibration are provided.  This workflow is then demonstrated in a watershed in Blacksburg, Virginia, where a unique MS4 permitting partnership allowed the development of these tools.  Finally, further improvements to the workflow are suggested along with ideas for additional research for stormwater management in Phase II MS4s.
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    Regulatory and Economic Consequences of Empirical Uncertainty for Urban Stormwater Management
    Aguilar, Marcus F. (Virginia Tech, 2016-10-10)
    The responsibility for mitigation of the ecological effects of urban stormwater runoff has been delegated to local government authorities through the Clean Water Act's National Pollutant Discharge Elimination Systems' Stormwater (NPDES SW), and Total Maximum Daily Load (TMDL) programs. These programs require that regulated entities reduce the discharge of pollutants from their storm drain systems to the "maximum extent practicable" (MEP), using a combination of structural and non-structural stormwater treatment — known as stormwater control measures (SCMs). The MEP regulatory paradigm acknowledges that there is empirical uncertainty regarding SCM pollutant reduction capacity, but that by monitoring, evaluation, and learning, this uncertainty can be reduced with time. The objective of this dissertation is to demonstrate the existing sources and magnitude of variability and uncertainty associated with the use of structural and non-structural SCMs towards the MEP goal, and to examine the extent to which the MEP paradigm of iterative implementation, monitoring, and learning is manifest in the current outcomes of the paradigm in Virginia. To do this, three research objectives were fulfilled. First, the non-structural SCMs employed in Virginia in response to the second phase of the NPDES SW program were catalogued, and the variability in what is considered a "compliant" stormwater program was evaluated. Next, the uncertainty of several commonly used stormwater flow measurement devices were quantified in the laboratory and field, and the importance of this uncertainty for regulatory compliance was discussed. Finally, the third research objective quantified the uncertainty associated with structural SCMs, as a result of measurement error and environmental stochasticity. The impacts of this uncertainty are discussed in the context of the large number of structural SCMs prescribed in TMDL Implementation Plans. The outcomes of this dissertation emphasize the challenge that empirical uncertainty creates for cost-effective spending of local resources on flood control and water quality improvements, while successfully complying with regulatory requirements. The MEP paradigm acknowledged this challenge, and while the findings of this dissertation confirm the flexibility of the MEP paradigm, they suggest that the resulting magnitude of SCM implementation has outpaced the ability to measure and functionally define SCM pollutant removal performance. This gap between implementation, monitoring, and improvement is discussed, and several potential paths forward are suggested.
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    Roanoke Urban Stormwater Research: Phase 1 - Discovery Final Report
    Dymond, Randel L.; Aguilar, Marcus F.; Bender, Paul; Hodges, Clayton Christopher (2014-12-01)
    This report is the final product of an 8 month long collaboration between the City of Roanoke’s Environmental, Engineering, Public Works, GIS, and Planning staff, and researchers in the Via Department of Civil and Environmental Engineering at Virginia Tech. This relationship was borne out of a mutual desire for improved urban stormwater science, with an anticipation that a long-term municipal-academic partnership would bring innovation to municipal stormwater management while providing opportunities to further the body of knowledge in this field. This report illustrates the City of Roanoke’s present political and environmental climate with respect to stormwater management by historical account and geographic context. It is descriptive and observational, providing both a foundation to proceed with future work, and a benchmark to measure success. The objective of this report is to characterize the regulations, people, and information that constitute stormwater management in the City of Roanoke. The Introduction is a summary of the City of Roanoke/Virginia Tech Urban Stormwater Research collaboration, and introduces the City as a densely urbanized political entity in the Upper Roanoke River watershed. The Introduction leads into Section I, a review of the Federal and State regulations that compel the City to prevent and treat stormwater runoff pollution, and a description of the City’s compliance strategies. Conversations with City staff and other stakeholders characterized these programs and helped contextualize stormwater management in the City and regionally; these conversations are recorded in Section II. City staff also supported the synopsis of City Geographic Information System data found in Section III by providing the necessary access. Section IV relates the quality and relevance of geographic datasets from external sources, and Section V does the same for water quality and quantity data. Section VI describes the pathways for general public engagement in stormwater in the City and regionally. The report body is bookended by Tables of Contents, Figures, and Tables at the front, and Index of Terms, References, and alphabetized Bibliography in the back. Supplemental information, including additional tables, figures, and text is found in the Appendices, organized using the same structure as the report. The submission of this report marks the end of the initial Discovery Phase of this research relationship; the resources have been discovered, collected, and organized. This also marks the commencement of the second phase, which focuses on a single City watershed as a precedent for future watershed planning. The completion of this first Phase, and even the anticipated completion of the next, do not bring finality to this work, but represent benchmarks along the way to the now unified objective of improving water quality in the City’s waterways – the terminal measure of success in this research project.