Groundwater-flow model of the Ozark Plateaus aquifer system, northwestern Arkansas, southeastern Kansas, southwestern Missouri, and northeastern Oklahoma

Abstract

To assess the effect that increased water use is having on the long-term availability of groundwater within the Ozark Plateaus aquifer system, a groundwater-flow model was developed using MODFLOW 2000 for a model area covering 7,340 square miles for parts of Arkansas, Kansas, Missouri, and Oklahoma. Vertically the model is divided into five units. From top to bottom these units of variable thickness are: the Western Interior Plains confining unit, the Springfield Plateau aquifer, the Ozark confining unit, the Ozark aquifer, and the St. Francois confining unit. Large mined zones contained within the Springfield Plateau aquifer are represented in the model as extensive voids with orders-of-magnitude larger hydraulic conductivity than the adjacent nonmined zones. Water-use data were compiled for the period 1960 to 2006, with the most complete data sets available for the period 1985 to 2006. In 2006, total water use from the Ozark aquifer for Missouri was 87 percent (8,531,520 cubic feet per day) of the total pumped from the Ozark aquifer, with Kansas at 7 percent (727,452 cubic feet per day), and Oklahoma at 6 percent (551,408 cubic feet per day); water use for Arkansas within the model area was minor. Water use in the model from the Springfield Plateau aquifer in 2005 was specified from reported and estimated values as 569,047 cubic feet per day. Calibration of the model was made against average water-level altitudes in the Ozark aquifer for the period 1980 to 1989 and against waterlevel altitudes obtained in 2006 for the Springfield Plateau and Ozark aquifers. Error in simulating water-level altitudes was largest where water-level altitude gradients were largest, particularly near large cones of depression. Groundwater flow within the model area occurs generally from the highlands of the Springfield Plateau in southwestern Missouri toward the west, with localized flow occurring towards rivers and pumping centers including the five largest pumping centers near Joplin

Useful Drainage Estimates Obtained from a Large‐Scale Soil Moisture Monitoring Network by Applying the Unit‐Gradient Assumption

“…At Miami, where the soil‐moisture‐based mean annual drainage rate is 158 mm yr −1 greater than the HYDRUS‐1D estimate, the HYDRUS‐1D estimates may be somewhat more reliable. The most recent groundwater modeling study encompassing this region, Czarnecki et al (2009), reviewed prior recharge estimates from the literature and calibrated a groundwater flow model by adjusting the recharge rates, resulting in a mean annual recharge of 46 mm yr −1 for the area encompassing the Miami site. This is consistent with the 59 mm yr −1 drainage rate at the 60‐cm depth estimated by HYDRUS‐1D.…”

“…The Garber‐Wellington aquifer in central Oklahoma is heavily used for public and domestic water supply (Mashburn et al, 2014). Other major aquifers in the eastern half of the state, such as the Antlers aquifer in the southeast (Morton, 1992), the Arkansas River aquifer in east‐central Oklahoma (Oklahoma Water Resources Board, 2012), and the Boone aquifer in the northeast (Czarnecki et al, 2009), are not heavily used at present; however, they may come under increasing pressure due to population growth. Preexisting recharge estimates for these major aquifers provide a primary means of evaluating the proposed soil‐moisture‐based drainage estimation method.…”

Development of a Numerical Multi-Layered Groundwater Model to Simulate Inter-Aquifer Water Exchange in Shelby County, Tennessee

“…The latter represents 97.5% of the total outflows from the UCCU. This reduction in storage water and flow through confining units has been documented by Czarnecki et al [93] and Masterson et al [94], where confining unit depletions due to storage release are of concern in certain areas of the U.S. because the water removed from clayey sediments cannot be replenished as these units gradually compress [94].…”