Assessment of Uncertainty in Time‐Related Capture Zones Using Conditional Simulation of Hydraulic Conductivity

Abstract

A stochastic approach to steady‐state time‐related capture zone determination that is based on the conditional simulation of hydraulic conductivity is presented. Conditional simulation of hydraulic conductivity preserves the spatial correlation structure of the real hydraulic conductivity field as well as the measured, or known, values of hydraulic conductivity at sampling locations, thereby optimizing the use of available data and providing the most representative results possible. The stochastic analysis methodology utilizing conditional simulation is applied to a hypothetical ground‐water system with a water supply well to estimate uncertainty in the 1‐year and 10‐year capture zones of the well. The results demonstrate the influence of known hydraulic conductivity values on the estimates of uncertainty, as well as the behavior of the “zone of uncertainty” of the capture zone as a function of travel time and orientation of regional flow. The results have significant implications regarding strategies for sampling aquifer properties (e.g., hydraulic conductivity) for capture zone delineation and for interpretation of the effects of hydraulic conductivity uncertainty on capture zones.

Characterization of soil lead by comparing sequential Gaussian simulation, simulated annealing simulation and kriging methods

“…Conditional simulation techniques have been applied in many ®elds. Notable examples include Varljen and Shafer (1991), Rouhani and others (1995), Eggleston and others (1996), Mowrer (1997), Sterk and Stein (1997), and Kentwell and others (1999). Furthermore, these techniques have been recently applied to characterize the spatial variability of pollutants.…”

Stochastic delineation of well capture zones

“…In the recent years, with the Monte Carlo method several studies have considered the variability of medium properties in delineating the well capture zone (Varljen and Shafer, 1991;Bair et al, 1991;Cole and Silliman, 1997;Franzetti and Guadagnini, 1996;Guadagnini and Franzetti, 1999;Riva et al, 1999;van Leeuwen et al, 1998). There are several problems with this probability-based approach in delineating well capture zones.…”

Optimization for Early-Warning Monitoring Networks in Well Catchments Should Be Multi-objective, Risk-Prioritized and Robust Against Uncertainty

“…Thus, there is always an inventory of risk sources in the catchment that remains to be assessed and controlled. Accordingly, there is ample literature on capture zone delineation and its uncertainty (e.g., Varljen and Shafer 1991;Jacobson et al 2002;Moutsopoulos et al 2008;Stauffer et al 2005), on aquifer vulnerability (e.g., Aller et al 1987;Overheu et al 2014;Zwahlen 2003), on (probabilistic) well vulnerability (e.g., Enzenhoefer et al 2012;Frind et al 2006;Enzenhoefer et al 2014), and on risk analysis (e.g., Cushman et al 2001;Tartakovsky 2013). While such works help to evaluate the risk sources to which the production well is exposed, it is not yet helpful in controlling them.…”