Transient Recharge Estimability Through Field‐Scale Groundwater Model Calibration

The estimation of recharge through groundwater model calibration is hampered by the nonuniqueness of recharge and aquifer parameter values. It has been shown recently that the estimability of spatially distributed recharge through calibration of steady‐state models for practical situations (i.e., re...

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Bibliographic Details
Published in:Ground water 2017-11, Vol.55 (6), p.827-840
Main Authors: Knowling, Matthew J., Werner, Adrian D.
Format: Article
Language:English
Subjects:
Aquifers
Calibration
Groundwater
Groundwater data
Groundwater levels
Groundwater recharge
Hydraulics
Mathematical models
Models, Theoretical
Parameter estimation
Parameters
Scale (ratio)
South Australia
Spatial data
Spatial distribution
Specific yield
Statistical analysis
Statistical methods
Steady state models
Storage
Temporal resolution
Variability
Water levels
Water Movements
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Summary:The estimation of recharge through groundwater model calibration is hampered by the nonuniqueness of recharge and aquifer parameter values. It has been shown recently that the estimability of spatially distributed recharge through calibration of steady‐state models for practical situations (i.e., real‐world, field‐scale aquifer settings) is limited by the need for excessive amounts of hydraulic‐parameter and groundwater‐level data. However, the extent to which temporal recharge variability can be informed through transient model calibration, which involves larger water‐level datasets, but requires the additional consideration of storage parameters, is presently unknown for practical situations. In this study, time‐varying recharge estimates, inferred through calibration of a field‐scale highly parameterized groundwater model, are systematically investigated subject to changes in (1) the degree to which hydraulic parameters including hydraulic conductivity (K) and specific yield (Sy) are constrained, (2) the number of water‐level calibration targets, and (3) the temporal resolution (up to monthly time steps) at which recharge is estimated. The analysis involves the use of a synthetic reality (a reference model) based on a groundwater model of Uley South Basin, South Australia. Identifiability statistics are used to evaluate the ability of recharge and hydraulic parameters to be estimated uniquely. Results show that reasonable estimates of monthly recharge (
ISSN:0017-467X
1745-6584
DOI:10.1111/gwat.12526