A New Zonation Algorithm with Parameter Estimation Using Hydraulic Head and Subsidence Observations. Issue 4 (2nd August 2013)

• Record Type: Journal Article
• Authors: Zhang, Meijing; Burbey, Thomas J.; Nunes, Vitor Dos Santos; Borggaard, Jeff
• Is Part Of: Ground water. Volume 52:Issue 4(2014:Jul./Aug.)
• Page Start: 514
• Page End: 524
• Publication Date: 2013-08-02
• Subjects: Groundwater -- Periodicals; Wells -- Periodicals; Eau souterraine -- Périodiques; Puits -- Périodiques; Grondwater; Eau souterraine; Puits; Electronic journals; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 551.49
• DOI: 10.1111/gwat.12102
• Languages: English
• ISSNs: 0017-467X

Abstract

<abstract abstract-type="main" id="gwat12102-abs-0001"> <title>Abstract</title> <p id="gwat12102-para-0001">Parameter estimation codes such as UCODE_2005 are becoming well‐known tools in groundwater modeling investigations. These programs estimate important parameter values such as transmissivity (<italic>T</italic>) and aquifer storage values (<italic>S</italic><sub>a</sub>) from known observations of hydraulic head, flow, or other physical quantities. One drawback inherent in these codes is that the parameter zones must be specified by the user. However, such knowledge is often unknown even if a detailed hydrogeological description is available. To overcome this deficiency, we present a discrete adjoint algorithm for identifying suitable zonations from hydraulic head and subsidence measurements, which are highly sensitive to both elastic (<italic>S</italic><sub>ske</sub>) and inelastic (<italic>S</italic><sub>skv</sub>) skeletal specific storage coefficients. With the advent of interferometric synthetic aperture radar (InSAR), distributed spatial and temporal subsidence measurements can be obtained. A synthetic conceptual model containing seven transmissivity zones, one aquifer storage zone and three interbed zones for elastic and inelastic storage coefficients were developed to simulate drawdown and subsidence in an aquifer interbedded with clay that exhibits delayed drainage. Simulated delayed land subsidence and groundwater head data are assumed to be the observed measurements, to which the discrete adjoint algorithm is called to create approximate spatial zonations of <italic>T</italic>, <italic>S</italic><sub>ske</sub>, and <italic>S</italic><sub>skv</sub>. UCODE‐2005 is then used to obtain the final optimal parameter values. Calibration results indicate that the estimated zonations calculated from the discrete adjoint algorithm closely approximate the true parameter zonations. This automation algorithm reduces the bias established by the initial distribution of zones and provides a robust parameter zonation distribution.</p> </abstract>