Three‐dimensional Bayesian geostatistical aquifer characterization at the Hanford 300 Area using tracer test data

Abstract

1] Tracer tests performed under natural or forced gradient flow conditions can provide useful information for characterizing subsurface properties, through monitoring, modeling, and interpretation of the tracer plume migration in an aquifer. Nonreactive tracer experiments were conducted at the Hanford 300 Area, along with constant-rate injection tests and electromagnetic borehole flowmeter tests. A Bayesian data assimilation technique, the method of anchored distributions (MAD) , was applied to assimilate the experimental tracer test data with the other types of data and to infer the threedimensional heterogeneous structure of the hydraulic conductivity in the saturated zone of the Hanford formation.In this study, the Bayesian prior information on the underlying random hydraulic conductivity field was obtained from previous field characterization efforts using constant-rate injection and borehole flowmeter test data. The posterior distribution of the conductivity field was obtained by further conditioning the field on the temporal moments of tracer breakthrough curves at various observation wells. MAD was implemented with the massively parallel three-dimensional flow and transport code PFLOTRAN to cope with the highly transient flow boundary conditions at the site and to meet the computational demands of MAD. A synthetic study proved that the proposed method could effectively invert tracer test data to capture the essential spatial heterogeneity of the three-dimensional hydraulic conductivity field. Application of MAD to actual field tracer data at the Hanford 300 Area demonstrates that inverting for spatial heterogeneity of hydraulic conductivity under transient flow conditions is challenging and more work is needed.Citation: Chen, X., H. Murakami, M. S. Hahn, G. E. Hammond, M. L. Rockhold, J. M. Zachara, and Y. Rubin (2012), Threedimensional Bayesian geostatistical aquifer characterization at the Hanford 300 Area using tracer test data, Water Resour. Res., 48, W06501,

Coupling a three-dimensional subsurface flow and transport model with a land surface model to simulate stream–aquifer–land interactions (CP v1.0)

“…The PDEs are spatially discretized using a finite-volume technique, and the backward Euler scheme is used for implicit time discretization. It has been widely used for simulating subsurface multiphase flow and reactive biogeochemical transport processes (Chen et al, , 2012Hammond and Lichtner, 2010;Hammond et al, 2011;Kumar et al, 2016;Lichtner and Hammond, 2012;Liu et al, 2016;Pau et al, 2014).…”

Software framework for inverse modeling and uncertainty characterization

“…MAD has been shown by Rubin et al (2010), Murakami et al (2011), andChen et al (2012) to be a flexible stochastic inverse modeling technique that addresses the first three challenges posed by Carrera et al (2005). Specifically, MAD can account for geology (Challenge #1) via the representation of geological features through SRFs modeled using structural parameters; handles multiple relevant data types (Challenge #2) through use of direct measurements and measurements that are indirectly related to the variable modeled; and accommodates uncertainty (Challenge #3) by explicitly incorporating observation uncertainties and quantifying uncertainty of geostatistical structural parameters and a new concept called "anchors".…”

Bayesian inversion of Mualem‐van Genuchten parameters in a multilayer soil profile: A data‐driven, assumption‐free likelihood function

“…The approach yields complete posterior probability distributions of the soil parameters. MAD has previously been applied to pumping as well as tracer test data obtained from field and synthetic studies for successful geostatistical and local parameter quantification [ Murakami et al ., ; Chen et al ., ; Over et al ., ].…”