Guidelines for Evaluating Ground-Water Flow Models

Reilly, Thomas E.; Harbaugh, Arlen W.

doi:10.3133/sir20045038

Cited by 104 publications

(101 citation statements)

References 29 publications

(7 reference statements)

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“…Clustering of residuals with similar magnitudes and signs is indicative of model bias (Reilly and Harbaugh, 2004). Overall, residuals ( fig.…”

Section: Normality Of Residuals and Goodness Of Fitmentioning

confidence: 94%

“…The accuracy of a groundwater model is limited by simplification of complexities within the groundwater-flow system (conceptual model), space and time discretization effects, assumptions made in the formulation of the governing flow equations, and simplifications of representations of boundary conditions and discretization and representation of climate. Model accuracy also is affected by cell size, number of layers, accuracy of boundary conditions, accuracy and availability of hydraulic property data, accuracy of withdrawal and areal recharge estimates, historical data for calibration, parameter sensitivity, and the interpolations and extrapolations that are inherent in using data in a model (Reilly and Harbaugh, 2004). The model provides a relatively good fit to groundwater levels in the Leon-Belding and Fort Stockton areas and spring flow from Comanche Springs.…”

Section: Model Limitationsmentioning

confidence: 99%

“…A large positive mean indicates that the model primarily overpredicts (simulated values greater than observed), and a negative mean indicates underprediction (simulated values less than observed). Low values of RMSE indicate better model fit to observed values (Anderson and Woessner, 1992;Reilly and Harbaugh, 2004).…”

Section: Model Fit and Model Errormentioning

confidence: 99%

See 2 more Smart Citations

Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

Clark¹,

Bumgarner²,

Houston³

et al. 2014

Scientific Investigations Report

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CRANE COUNTY Belding Fort Stockton Pecos R iv e rObliqueFor more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprodTo order this and other USGS information products, visit http://store.usgs.gov Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD83).Altitude, as used in this report, refers to distance above the vertical datum. Simulation of Groundwater Flow in the Edwards-Trinity and Related Aquifers in the Pecos County Region, TexasBy Brian R. Clark, Johnathan R. Bumgarner, Natalie A. Houston, and Adam L. Foster AbstractThe Edwards-Trinity aquifer is a vital groundwater resource for agricultural, industrial, and public supply uses in the Pecos County region of western Texas. The U.S. Geological Survey completed a comprehensive, integrated analysis of available hydrogeologic data to develop a numerical groundwater-flow model of the Edwards-Trinity and related aquifers in the study area in parts of Brewster, Jeff Davis, Pecos, and Reeves Counties. The active model area covers about 3,400 square miles of the Pecos County region of Texas west of the Pecos River, and its boundaries were defined to include the saturated areas of the Edwards-Trinity aquifer. (2008) pumping rates as assigned in scenario 1 with year-round maximum permitted pumping rates in the Belding area. Results of scenario 2 are similar in waterlevel decline and extent as those of scenario 1. The extent of the projected groundwater-level decline in the range from 5.0 to 15.0 feet in the Leon-Belding irrigation area expanded slightly (about a 2-percent increase) from that of scenario 1. Maximum projected groundwater-level declines in the Leon-Belding irrigation area were approximately 31.3 feet in small isolated areas. Scenario 3 evaluated the effects of periodic increases in pumping rates over the 30-year extended period. Results of scenario 3 are similar to those of scenario 2 in terms of the areas of groundwater-level decline; however, the maximum projected groundwater-level decline increased to approximately 34.5 feet in the Leon-Belding area, and the extent of the decline was larger in area (about a 17-percent increase) than that of scenario 2. Additionally, the area of projected groundwater-level declines in the eastern part of the model area increased from that of scenario 2-two individual areas of decline coalesced into one larger area. The localized nature of the projected groundwater-level de...

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“…Clustering of residuals with similar magnitudes and signs is indicative of model bias (Reilly and Harbaugh, 2004). Overall, residuals ( fig.…”

Section: Normality Of Residuals and Goodness Of Fitmentioning

confidence: 94%

Section: Model Limitationsmentioning

confidence: 99%

See 1 more Smart Citation

Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

Clark¹,

Bumgarner²,

Houston³

et al. 2014

Scientific Investigations Report

View full text Add to dashboard Cite

show abstract

“…Both of these conditions could ultimately affect the model-estimated hydraulic-conductivity field owing to nonunique solutions that satisfy the calibration targets. The use of specified constant-head boundaries to simulate the model boundary flows limits the model's effectiveness in evaluating groundwater development near the model boundary (Reilly and Harbaugh, 2004;Brooks and others, 2014).…”

Section: Boundary Flowsmentioning

confidence: 99%

An update of the Death Valley regional groundwater flow system transient model, Nevada and California

Belcher¹,

Sweetkind²,

Faunt³

et al. 2017

Scientific Investigations Report

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“…Historically, hydrochemical analyses are not often used to constrain catchment-scale water balance modelling (Reilly and Harbaugh, 2004;Barnett et al, 2012), despite Scanlon et al (2002) highlighting the need to use multiple techniques (including hydrochemical insights) to increase the reliability of recharge and discharge estimates. Geochemical data can improve our understanding of groundwater mixing processes because of the potential to trace pathways of groundwater movement and water-rock interactions, whilst also providing insights into the impacts of past groundwater extractions (Edmunds, 2009;Martinez et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquifer

Iverach

Cendón

Meredith

et al. 2017

Hydrol. Earth Syst. Sci.

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Abstract. Understanding pathways of recharge to alluvial aquifers is important for maintaining sustainable access to groundwater resources. Water balance modelling is often used to proportion recharge components and guide sustainable groundwater allocations. However, it is not common practice to use hydrochemical evidence to inform and constrain these models. Here we compare geochemical versus water balance model estimates of artesian discharge into an alluvial aquifer, and demonstrate why multi-tracer geochemical analyses should be used as a critical component of water budget assessments. We selected a site in Australia where the Great Artesian Basin (GAB), the largest artesian basin in the world, discharges into the Lower Namoi Alluvium (LNA), an extensively modelled aquifer, to convey the utility of our approach. Water stable isotopes (δ 18 O and δ 2 H) and the concentrations of Na + and HCO − 3 suggest a continuum of mixing in the alluvial aquifer between the GAB (artesian component) and surface recharge, whilst isotopic tracers ( 3 H, 14 C, and 36 Cl) indicate that the alluvial groundwater is a mixture of groundwaters with residence times of < 70 years and groundwater that is potentially hundreds of thousands of years old, which is consistent with that of the GAB. In addition, Cl − concentrations provide a means to calculate a percentage estimate of the artesian contribution to the alluvial groundwater. In some locations, an artesian contribution of up to 70 % is evident from the geochemical analyses, a finding that contrasts with previous regional-scale water balance modelling estimates that attributed 22 % of all inflow for the corresponding zone within the LNA to GAB discharge. Our results show that hydrochemical investigations need to be undertaken as part of developing the conceptual framework of a catchment water balance model, as they can improve our understanding of recharge pathways and better constrain artesian discharge to an alluvial aquifer.

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Guidelines for Evaluating Ground-Water Flow Models

Cited by 104 publications

References 29 publications

Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

Simulation of groundwater flow in the Edwards-Trinity and related aquifers in the Pecos County region, Texas

An update of the Death Valley regional groundwater flow system transient model, Nevada and California

A multi-tracer approach to constraining artesian groundwater discharge into an alluvial aquifer

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