Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-2 (of 2 Records) |
Query Trace: Anderson BA[original query] |
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"Complexities in hindcasting models - when should we say enough is enough,"
Maslia ML , Aral MM , Faye RE , Grayman WM , Suarez-Soto RJ , Sautner JB , Anderson BA , Bove FJ , Ruckart PZ , Moore SM . Ground Water 2011 50 (1) 10-6; discussion 16-8 In a recent article, TP Clement (2010, hereafter referred to as TPC) discusses the complexities and limitations of "hindcasting" models and criticizes the use of complex models when undertaking investigations of subsurface reactive transport processes. TPC implies that complex numerical models that stimulate reactive transport processes in groundwater are likely if not always an inappropriate tool to apply to "hindcasting" investiagtions and that scientists and engineers who implement these investiagtions using such models are somehow not aware of teh technical and scientific complexities and limitations of such methods and approaches. To illustrate his point of view, TPC uses a case study of an ongoing health study of exposure to volatile organic compounds (VOCs) in drinking water at US Marine Corps Base Camp Lejeune, North Carolina (hereafter referred to as the case-control health study at Camp Lejeune). The article presents some thought-provoking points-of-view. However, we believe there is a lack of detail on several key issues that require specificity and clarification, particularly with respect to modleing approaches and methods, the physics of containment occurrence and reactive transport in teh subsurface, and agency policies for the review and dissemination of data and reports. |
Stochastic analysis of pesticide transport in the shallow groundwater of Oatland Island, Georgia, USA
Anderson BA , Maslia ML , Caparoso JL , Ausdemore D , Aral MM . Water Qual Expo Health 2010 2 (1) 47-64 Analytical models, when used in stochastic analysis mode, may provide an effective tool for making informed management decisions for simplified environmental systems. This approach was used to evaluate migration of an organochlorine pesticide plume in a shallow, unconfined aquifer underlying a barrier island in coastal Georgia, USA. The contaminant plume at the site consists of four isomers of benzene hexachloride (BHC), also known as hexachlorocyclohexane (HCH). The deterministic analysis conducted at the site, which used calibrated, single-value input parameters, indicates that the contaminant plume will not reach wetlands that are downgradient of the source. Given the uncertainties involved in the deterministic analysis, this outcome was not considered to be sufficient to make effective management decisions at the site. Subsequently, probabilistic analysis using a range of input parameter values was conducted to estimate the risk that the pesticide plume would reach the downgradient wetlands. The two-stage Monte Carlo analysis that was conducted indicates the probability that contaminant levels will exceed the detection limit of BHC (0.044 micrograms per liter) at the wetlands increases from 1 percent to a maximum of 13 percent during the period 2005-2065. This represents an 87% or greater confidence level that the pesticide plume will not reach the wetlands. This outcome was used to inform environmental management decisions at the site. The modeling analysis was conducted using the publicly available analytical contaminant transport analysis system (ACTS) software. |
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