US GEOLOGICAL SURVEY Files

FAQ on the Northern Arizona Regional Groundwater Flow Model (NARGFM)

After securing project funding in 1999, the Arizona Department of Water Resources (ADWR) asked the USGS to develop a regional groundwater flow model for the north-central part of the State. In making this request, "the Department was fully aware of the capability of the USGS to develop an unbiased model that would improve understanding of the groundwater system and ultimately management of the region's water resources," according to Thomas G. Whitmer, ADWR's Manager of Statewide Water Planning. View Document.

Geologic Framework of Aquifer Units and Ground-Water Flowpaths, Verde River Headwaters, North-Central Arizona

Abstract: This study combines the results of geophysical, geologic, and geochemical investigations to provide a hydrogeologic framework of major aquifer units, identify ground-water flowpaths, and determine source(s) of base flow to the upper Verde River. This introductory chapter provides an overview of previous studies, predevelopment conditions, present surface-water and ground-water conditions, and a conceptual water budget of the hydrologic system. In subsequent chapters, this conceptual model will be evaluated and refined with respect to the results of each successive investigation. First, a compilation of mapping and field verification of the surficial geology, reinterpretation of driller’s logs, and contour mapping of alluvial thicknesses and buried volcanic rocks provide new three-dimensional geologic information. Second, a suite of geophysical techniques—including aeromagnetic and gravity surveys and inverse modeling approaches—was used to interpret the deeper subsurface geology. Third, geologic, geo- physical, and hydrological data were integrated to define basin boundaries, describe aquifer units in the basin-fill aquifers of Big and Little Chino valleys and the regional carbonate aquifer north of the upper Verde River, and develop a hydrogeologic framework. Water-level gradients were used to infer outlet flowpaths from the basin-fill aquifers through the carbonate aquifer toward the upper Verde River. Fourth, geochemical investigations employing analyses of dissolved major and trace elements and isotopes of δD, δ18O, 3H, 13C, and 14C were used to characterize major aquifers, identify recharge areas, and determine evolution of water chemistry along ground-water flowpaths. Fifth, results of a tracer-dilution study and synoptic sampling identify locations of major spring inflows discharging to the upper Verde River, measure base-flow contributions, which were used to calculate the relative contributions from each aquifer to upper Verde River springs using inverse geo- chemical modeling. In the final chapter, synthesis of multiple lines of evidence improve understanding of the relationships between the three aquifers, regional ground-water flowpaths, and the proportion of flow from each aquifer to the upper Verde River. Collectively, data from many varied and indepen-dent sources improves confidence in the conceptual model of the hydrogeologic system.

This file consists of 7 chapters and 246 pages totaling 135 mb. It can be downloaded here. 

Geologic Map of Prescott National Forest and the Headwaters of the Verde River

This file is a 95 mb detailed geologic map. It can be downloaded here.

Hydrogeology of the Upper and Middle Verde River Watersheds, Central Arizona

The upper and middle Verde River watersheds in central Arizona are primarily in Yavapai County, which in 1999 was determined to be the fastest growing rural county in the United States; by 2050 the population is projected to more than double its current size (132,000 in 2000). This study combines climatic, surface water, groundwater, water chemistry, and geologic data to describe the hydrogeologic systems within the upper and middle Verde River watersheds and to provide a conceptual understanding of the ground-water flow system. The study area includes the Big Chino and Little Chino subbasins in the upper Verde River watershed and the Verde Valley subbasin in the middle Verde River watershed. USGS report by Kyle Blasch. View Document.

Investigation of the Geology and Hydrology of the Upper and Middle Verde River Watershed of Central Arizona: Summary Report

In 1999, the U.S. Geological Survey (USGS), in cooperation with the Arizona Department of Water Resources (ADWR), initiated a regional investigation of the hydrogeology of the upper and middle Verde River watershed. The project is part of the Rural Watershed Initiative (RWI), a program established by the State of Arizona and managed by the ADWR that addresses water supply issues in rural areas while encouraging participation from stakeholder groups in affected communities. The USGS is performing similar RWI investigations on the Colorado Plateau to the north and in the Mogollon Highlands to the east of the Verde River study area (Parker and Flynn, 2000). The objectives of the RWI investigations are to develop: (1) a single database containing all hydrogeologic data available for the combined areas, (2) an understanding of the geologic units and structures in each area with a focus on how geology influences the storage and movement of ground water, (3) a conceptual model that describes where and how much water enters, flows through, and exits the hydrogeologic system, and (4) a numerical ground-water flow model that can be used to improve understanding of the hydrogeologic system and to test
test the effects of various scenarios of water-resources development. In 2001, Yavapai County became an additional cooperator in the upper and middle Verde River RWI investigation. View Document.

Middle Verde Resource Analysis

Presentation slides describing VRBP project with USGS to better define water resources in the Verde Valley. View Document.

Possible Effects of Groundwater Pumping on Surface Water in the Verde Valley, Arizona

The U.S. Geological Survey (USGS), in cooperation with The Nature Conservancy, has applied a groundwater model to simulate effects of groundwater pumping and artificial recharge on surface water in the Verde Valley sub-basin of Arizona. This is the summary of the full report. Results are in two sets of maps that show effects of locations of pumping or recharge on streamflow. These maps will help managers make decisions that will meet water needs and minimize environmental impacts. View Document.

Regional Groundwater-Flow Model of the Redwall-Muav, Coconino, and Alluvial Basin Aquifer Systems of Northern and Central Arizona (NARGFM)

Results of a major effort by USGS: a numerical flow model of the groundwater flow system in the primary aquifers in northern Arizona was developed to simulate interactions between the aquifers, perennial streams, and springs for predevelopment and transient conditions during 1910 through 2005. Simulated aquifers include the Redwall-Muav, Coconino, and basin-fill aquifers. Perennial stream reaches and springs that derive base flow from the aquifers were simulated, including the Colorado River, Little Colorado River, Salt River, Verde River, and perennial reaches of tributary streams. Simulated major springs include Blue Spring, Del Rio Springs, Havasu Springs, Verde River headwater springs, several springs that discharge adjacent to major Verde River tributaries, and many springs that discharge to the Colorado River. View Document.

Simulated Effects of Groundwater Pumping and Artificial Recharge on Surface-Water Resources and Riparian Vegetation in the Verde Valley Sub-Basin, Central Arizona

A USGS publication. In the Verde Valley sub-basin, groundwater use has increased in recent decades. Residents and stakeholders in the area have established several groups to help in planning for sustainability of water and other resources of the area. One of the issues of concern is the effect of groundwater pumping in the sub-basin on surface water and on groundwater- dependent riparian vegetation. The Northern Arizona Regional Groundwater-Flow Model by Pool and others is the most comprehensive and up-to-date tool available to under- stand the effects of groundwater pumping in the sub-basin. Using a procedure by Leake and others (2008), this model was modified and used to calculate effects of groundwater pumping on surface-water flow and evapotranspiration for areas in the sub-basin. This report presents results for the upper two model layers for pumping durations of 10 and 50 years. Results are in the form of maps that indicate the fraction of the well pumping rate that can be accounted for as the combined effect of reduced surface-water flow and evapotranspiration. In general, the highest and most rapid responses to pumping were computed to occur near surface-water features simulated in the modified model, but results are not uniform along these features. The results are intended to indicate general patterns of model-computed response over large areas. For site-specific projects, improved results may require detailed studies of the local hydrologic conditions and a refinement of the modified model in the area of interest. View Document.

Sources of springs supplying base flow to the Verde River headwaters, Yavapai County, Arizona

Multiple lines of evidence were used to identify source aquifers, quantify their respective contributions, and trace the ground-water flow paths that supply base flow to the uppermost reach of the Verde River in Yavapai County, Arizona. Ground-water discharge via springs provides base flow for a 24-mile long reach from the mouth of Granite Creek (river mile 2.0) to Perkinsville (river mile 26). The flowing reach is important to downstream water users, maintains critical habitat for the recovery of native fish species, and has been designated a Wild and Scenic River. Sources of base flow are deduced from (a) geologic information, (b) ground-water levels, (c) precipitation and streamflow records, (d) downstream changes in base-flow measurements, (e) hydrologic analysis of water-budget components, and (f) stable- isotope geochemistry of ground water, surface water, and springs. Combined, this information clearly indicates that interconnected aquifers in Big Chino Valley are the primary source of Big Chino Springs, presently supplying at least 80 percent of the upper Verde River's base flow. Published by USGS; author Laurie Wirt. View Document.

Spatial and Seasonal Variability of Base Flow in the Verde Valley, Central Arizona, 2007 and 2011

Synoptic base-flow surveys were conducted on streams in the Verde Valley, central Arizona, in June 2007 and February 2011 by the U.S. Geological Survey (USGS), in coopera- tion with the Verde River Basin Partnership, the Town of Clarkdale, and Yavapai County. These surveys, also known as seepage runs, measured streamflow under base-flow condi- tions at many locations over a short period of time. Surveys were conducted on a segment of the Verde River that flows through the Verde Valley, between USGS streamflow-gaging stations 09504000 and 09506000, a distance of 51 river miles. Data from the surveys were used to investigate the domi- nant controls on Verde River base flow, spatial variability in gaining and losing reaches, and the effects that human altera- tions have on base flow in the surface-water system. The most prominent human alterations in the Verde Valley are dozens of surface-water diversions from streams, including gravity-fed ditch diversions along the Verde River.
Base flow that entered the Verde River from the tributary streams of Oak Creek, Beaver Creek, and West Clear Creek was found to be a major source of base flow in the Verde River. Groundwater discharge directly into the Verde River near these three confluences also was an important contributor of base flow to the Verde River, particularly near the conflu- ence with Beaver Creek. An examination of individual reaches of the Verde River in the Verde Valley found three reaches (largely unaffected by ditch diversions) exhibiting a similar pattern: a small net groundwater discharge in February 2011 (12 cubic feet per second or less) and a small net streamflow loss in June 2007 (11 cubic feet per second or less). Two reaches heavily affected by ditch diversions were difficult to interpret because of the large number of confounding human factors. Possible lower and upper bounds of net groundwater flux were calculated for all reaches, including those heavily affected by ditches. View Document.

USGS Publishes Verde Valley Seepage-Run Report

Substantially more water than necessary is diverted from the River during every growing season to support irrigation of farm fields, gardens, and lawns. Increased efficiency of the diversions and the irrigation they support will be essential to keeping more water in the river and protecting the Verde Valley's habitat and lifestyle. Published by the Verde River Basin Partnership. View Document.

Verde River Base Flow

Graph of base flow along the river from headwaters to Camp Verde taken from the Blasch report. View Document.