Methods and results for estimating the hydraulic characteristics of the subsurface materials in the Harney Basin, Oregon

Gerald H. Grondin, Darrick E. Boschmann, Halley J. Schibel, Benjamin P. Scandella., Title from PDF cover (viewed on December 20, 2021)., This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes., Includes bibliographical references (pages 56-63)., Mode of access: Internet from the Oregon Government Publications Collection., Text in English.
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This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.
Abstract/Description: A joint U.S. Geological Survey and Oregon Water Resources Department Harney Basin groundwater investigation was conducted to better define the 5,243 mi2 Harney Basin groundwater system, its water budget, and its response to groundwater development. Observed groundwater level declines and questions about groundwater resource sustainability prompted the investigation. This report presents the hydraulic properties of the basin's subsurface materials. The investigation used existing data from one aquifer-interference test, two automated groundwater level recorders at wells influenced by nearby pumping wells, 41 single well pump tests, and more than 1,000 well yield tests to characterize the hydraulic properties of 18 stratigraphic units grouped into nine hydrostratigraphic units. The data from these tests can be divided into two data categories (aquifer test data and specific capacity data) that required using different data analysis methods (graphical method and numerical method respectively). All the tests yielded data useful to characterize well response to pumping (specific capacity) and subsurface control on groundwater flow (transmissivity by all tests and hydraulic conductivity by most tests). Only the two automated groundwater level recorders yielded data sufficient to calculate groundwater storage coefficients. Only the one aquifer-interference test yielded sufficient data to indicate possible deformability, plasticity, and/or elasticity of one or more Harney Basin subsurface materials. Analyses indicate specific capacity, transmissivity, and hydraulic conductivity values are generally spatially ubiquitous for smaller values and increasingly spatially segregated for the largest values. The largest value range is most concentrated along the Harney Valley perimeter and the Riley vicinity. The largest median hydraulic property values relate to younger volcanic deposits, intermediate median values relate to Silicic and High Lava Plains volcanic deposits and basin-fill sediments, and the smallest median values generally relate to upland deposits. The two storage coefficient values available indicate unconfined to intermediate (between confined and unconfined) groundwater storage. Conducting additional tests (single pumping well with observation wells) to more completely characterize the shallow and deep, upland and lowland hydraulic property, particularly storage coefficient, of each hydrostratigraphic unit is recommended. The test results would refine well to well interaction calculations and aid future groundwater modeling efforts to characterize Harney Basin groundwater flow and storage under various conditions or scenarios.
Subject(s): n-us-or
Groundwater flow -- Oregon -- Harney Basin -- Evaluation
Groundwater flow -- Oregon -- Harney Basin -- Mathematical models
Aquifers -- Oregon -- Harney Basin -- Evaluation
Aquifers -- Oregon -- Harney Basin -- Mathematical models
Wells -- Oregon -- Harney Basin -- Evaluation
Wells -- Oregon -- Harney Basin -- Fluid dynamics -- Mathematical models
Date Issued: 2021