U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2004-5215
By: Brian P. Kelly U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers and the U.S. Army
The Missouri River alluvial aquifer near Ft. Leavenworth, Kansas, supplies all or part of the drinking water for Ft. Leavenworth; Leavenworth, Kansas; Weston, Missouri; and cooling water for the Kansas City Power and Light, Iatan Power Plant. Ground water at three sites within the alluvial aquifer near the Ft. Leavenworth well field is contaminated with trace metals and organic compounds and concerns have been raised about the potential contamination of drinking-water supplies. In 2001, the U.S. Geological Survey, U.S. Army Corps of Engineers, and the U.S. Army began a study of ground-water flow in the Missouri River alluvial aquifer near Ft. Leavenworth.
Hydrogeologic data from 173 locations in the study area was used to construct a ground-water flow model (MODFLOW-2000) and particle-tracking program (MODPATH) to determine the direction and travel time of ground-water flow and contributing recharge areas for water-supply well fields within the alluvial aquifer. The modeled area is 28.6 kilometers by 32.6 kilometers and contains the entire study area. The model uses a uniform grid size of 100 meters by 100 meters and contains 372,944 cells in 4 layers, 286 columns, and 326 rows. The model represents the alluvial aquifer using four layers of variable thickness with no intervening confining layers.
The model was calibrated to both quasi-steady-state and transient hydraulic head data collected during the study and ground-water flow was simulated for five well-pumping/river-stage scenarios. The model accuracy was calculated using the root mean square error between actual measurements of hydraulic head and model generated hydraulic head at the end of each model run. The accepted error for the model calibrations were below the maximum measurement errors. The error for the quasi-steady-state calibration was 0.82 meter; for the transient calibration it was 0.33 meter.
The shape, size, and ground-water travel time within the contributing recharge area for each well or well field is affected by changes in river stage and pumping rates and by the location of the well or well field with respect to the major rivers, alluvial valley walls, and other pumping wells. The shapes of the simulated contributing recharge areas for the well fields in the study area are elongated in the upstream direction for all well-pumping/river-stage scenarios. The capture of ground water by the pumping wells as it moved downgradient toward the Missouri River caused the long up-valley extent of the contributing recharge areas. Recharge to the Iatan and Weston well fields primarily is from precipitation and surface runoff from the surrounding uplands because the contributing recharge area does not intersect the Missouri River for any well-pumping/river-stage scenarios. Recharge to the Leavenworth and Ft. Leavenworth well fields is from precipitation, surface runoff from the surrounding uplands, and the Missouri River because the contributing recharge area intersects these boundaries for all well-pumping/river-stage scenarios.
Particle tracking analysis indicated ground water from the three contaminated sites was captured by the Ft. Leavenworth well field for all well-pumping/river-stage scenarios. Ground-water travel times to the Ft. Leavenworth well field for average well-pumping/river-stage scenario ranged from about 33 years for the closest contamination site to about 71 years for the farthest contamination site. Ground-water flow was induced below the Missouri River by the Ft. Leavenworth and Leavenworth well fields for all well-pumping/river-stage scenarios.
TABLE OF CONTENTS
Purpose and Scope
Study Area Description
Physiography and Drainage
Bedrock and Valley Walls
Hydrology and Conceptual Ground-Water Flow Model
Hydraulic Properties of the Aquifer
Rivers and Lakes
Alluvial Valley Walls and Bedrock
Upstream and Downstream Aquifer Boundaries
Simulation of Ground-Water Flow
Boundary and Initial Conditions Parameters and Model Zones
Quasi-Steady-State and Transient Calibration
Contributing Recharge Areas and Ground-Water Travel Time
Pumping- and River-Stage Scenarios
Iatan Power Plant Well Field
Weston Well Field
Leavenworth Well Field
Ft. Leavenworth Well Field
Individual wells of the Ft. Leavenworth Well Field
Hydrologic Controls On Contributing Recharge Areas
Figures 1–9. Maps showing—
|meter (m)||3.281||foot (ft)|
|kilometer (km)||0.6214||mile (mi)|
|square meter (m2)||10.76||square foot (ft2)|
|square kilometer (km2)||0.3861||square mile (mi2)|
|cubic meter (m3)||0.0008107||acre-foot (acre-ft)|
|meter per day (m/d)||3.281||foot per day (ft/d)|
|cubic meter per second (m3/s)||35.31||cubic foot per second (ft3/s)|
|cubic meter per day (m3/d)||35.31||cubic foot per day (ft3/d)|
|cubic meter per day (m3/d)||264.2||gallon per day (gal/d)|
|cubic meter per day per square kilometer [(m3/d)/km2]||684.28||gallon per day per square mile [(gal/d)/mi2]|
|cubic meter per second (m3/s)||22.83||million gallons per day (Mgal/d)|
|cubic meter per day per square kilometer [(m3/d)/km2]||0.0006844|
million gallons per day per square mile [(Mga/d)/mi2]
|meter per day (m/d)||3.281 foot||per day (ft/d)|
|meter squared per day (m2/d)||10.76||foot squared per day (ft2/d)|
Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:
°F = (1.8 x °C) + 32
Altitude, as used in this report, refers to distance above the National Geodetic Vertical Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of both the United States and Canada, formerly called Sea Level Datum of 1929.
*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot squared per day (ft2/d), is used for convenience.
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For more information about USGS activities in Missouri contact:
U.S. Geological Survey
Water Resources Discipline
1400 Independence Road
Rolla, Missouri 65401
Telephone: (573) 308-3667
Fax: (573) 308-3645
or access the USGS Water Resources of Missouri home page at: http://mo.water.usgs.gov/.
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Last modified: Thursday, January 10 2013, 06:39:07 PM