Groundwater Resources in the Piedmont and Shenandoah Valley: A Comparison of Geologic Controls on Groundwater Quality and Sustainability PART I: Shenandoah Valley Enhanced Understanding for Aquifer Health Mark D. Kozar, USGS Washington WSC, Tacoma WA Dick Yager, USGS New York WSC, Ithaca NY Kurt J. McCoy, George Harlow, and Dave Nelms USGS Virginia WSC, Richmond VA

Whitings Neck Cave CAVES OF THE EASTERN PANHANDLE Not that many caves –42 known caves in Jefferson County –48 known caves in Berkeley County Most are short and not of hydrological interest Karst Continuum Model

3,300 mi mi 2 10 mi 2 Outline – Nested Modeling What is important for aquifer health depends on scale Shenandoah Valley (Yager et al, 2009) Opequon Creek (Kozar and Weary, 2009) Leetown Science Center (Kozar et al, 2007)

Structure Shenandoah Valley Model 3,300 mi 2 Yager, RM, Voss, CI, Southworth, S, 2009, Comparison of alternative representations of hydraulic-conductivity anisotropy in folded fractured-sedimentary rock: modeling groundwater flow in the Shenandoah Valley (USA): Hydrogeology Journal, v. 17, p

Shenandoah Valley Regional Conceptual Model (Yager et al., 2009)

Numerical Representation Of Regional Scale Anisotropy (Yager et al., 2009) Groundwater flows along preferential paths

Well Capture zones – Influence of Anisotropy

Meso Scale - Opequon Creek Model

Meso-Scale (300 mi 2 ) Conceptual Model Epikarst FracturedKarst FracturedRock Photo courtesy of Craig Wagnell (portaec.net) Photo by Wil Orndorff

Influence of Lithology – ALL ROCKS ARE NOT ALIKE

Leetown Ground- Water Flow Model Three layer model Tectonic Deformation KARST Vertical permeability contrast Fault Orientation

Fracture Orientations in the Leetown Area, WV Major fractures occur parallel to regional strike N. 20 o E. and perpendicular to strike. Thrust faults parallel to strike and cross strike faults are especially important controls on ground-water flow. Fractures mapped by a) Jones and Deike, 1981 and b) McCoy and others, 2005

Faults Fold Hinges or Lithologic Contacts Fracture-Flow Deformation Orthogonal Fracturing Bed-limited permeability Karst zones

Gradient

Leetown Surface Geophysics – AMT Plan View X-Sect View

Scale-Related Evolution of Conceptual Models Primary Deposition Heterogeneity Tectonic Deformation 3,300 mi mi 2 10 mi 2

Conclusions Nested Models – Scale Dependent Controls on Flow Basin Geometry Orderly Preferential Flow Paths Carbonate Heterogeneity Not All Rocks are Alike Fault Zone Hydrology Important Routes to Drain The Aquifer