The Use of MODFLOW with New Surface Water Modules for Evaluating Proposed Water Management System Improvements in North Miami-Dade County, Florida

Wilsnack, M. M.; Welter, David; McMunigal, C. L.; Montoya, Angela M.; Obeysekera, Jayantha

doi:10.1061/40562(267)10

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…Most commonly, a uniform distribution of porosity within the model domain is assumed. For example, a constant 20 percent specific yield has been applied to the uppermost layer of the model layer in north Miami-Dade County (Wilsnack et al, 2000) and in Northwest well-field ground-water flow models (CH2M-HILL, 2001). Backward-tracked flow pathlines were defined, assuming that the porosity of the Biscayne aquifer is 20 percent and uniformly distributed (CH2M-HILL, 2001;Guha, 2005).…”

Section: Hydraulic Test Activitiesmentioning

confidence: 99%

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

Renken

Cunningham

Zygnerski

et al. 2005

Environmental and Engineering Geoscience

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Proposed expansion of extractive lime-rock mines near the Miami-Dade County Northwest well field and Everglades wetland areas has garnered intense scrutiny by government, public, environmental stakeholders, and the media because of concern that mining will increase the risk of pathogen contamination. Rock mines are excavated to the same depth as the well field's primary producing zone. The underlying karst Biscayne aquifer is a triple-porosity system characterized by (1) a matrix of interparticle porosity and separate vug porosity; (2) touching-vug porosity that forms preferred, stratiform passageways; and, less commonly, (3) conduit porosity formed by thin solution pipes, bedding-plane vugs, and cavernous vugs. Existing ground-water flow and particle tracking models do not provide adequate information regarding the ability of the aquifer to limit the advective movement of pathogens and other contaminants. Chemical transport and colloidal mobility properties have been delineated using conservative and microsphere-surrogate tracers for Cryptosporidium parvum. Forced-gradient tests were executed by introducing conservative tracers into injection wells located 100 m (328 ft) from a municipal-supply well. Apparent mean advective velocity between the wells is one to two orders of magnitude greater than previously measured. Touching-vug, stratiform flow zones are efficient pathways for tracer movement at the well field. The effective porosity for a continuum model between the point of injection and tracer recovery ranges from 2 to 4 percent and is an order of magnitude smaller than previously assumed. Existing well-field protection zones were established using porosity estimates based on specific yield. The effective, or kinematic, porosity of a Biscayne aquifer continuum model is lower than the total porosity, because high velocities occur along preferential flow paths that result in faster times of travel than can be represented with the ground-water flow equation. Tracer tests indicate that the relative ease of contaminant movement to municipal supply wells is much greater than previously considered.

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Section: Hydraulic Test Activitiesmentioning

confidence: 99%

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

Renken

Cunningham

Zygnerski

et al. 2005

Environmental and Engineering Geoscience

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“…To develop a water budget that meets natural, agricultural, and urban needs, it is necessary to accurately model the movement of ground water and associated loads from the surface-water storage areas to the coast-an approach that involves numerical simulation of ground-water flow and solute transport in the Biscayne aquifer. Recent ground-water flow models for the Biscayne aquifer assume flow through porous media (Nemeth and others, 2000;Wilsnak and others, 2000;Langevin, 2001;Sonenshein, 2001); however, the Biscayne aquifer is a triple-porosity (matrix, touching-vug, and conduit porosity) karst aquifer (Vacher and Mylroie, 2002;Cunningham and others, 2004b;2004c). As a consequence, rates of flow within the conduit pore system can be more rapid than within the matrix, as demonstrated by a tracer test conducted by the U.S. Geological Survey (USGS) at the Northwest Well Field (NWWF) in Miami-Dade County (Renken and others, 2005).…”

Section: Introductionmentioning

confidence: 99%

A cyclostratigraphic and borehole-geophysical approach to development of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer, southeastern Florida

Cunningham¹,

Wacker²,

Robinson³

et al. 2006

Scientific Investigations Report

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The Use of MODFLOW with New Surface Water Modules for Evaluating Proposed Water Management System Improvements in North Miami-Dade County, Florida

Cited by 3 publications

References 3 publications

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

Assessing the Vulnerability of a Municipal Well Field to Contamination in a Karst Aquifer

A cyclostratigraphic and borehole-geophysical approach to development of a three-dimensional conceptual hydrogeologic model of the karstic Biscayne aquifer, southeastern Florida

Representation of surface-water flows using Gradient-Related Discharge in an Everglades Network

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