13 research outputs found
Recommended from our members
Sea water intrusion model of Amchitka Island, Alaska
During the 1960s and 1970s, Amchitka Island, Alaska, was the site of three underground nuclear tests, referred to as Milrow, Long Shot and Cannikin. Amchitka Island is located in the western part of the Aleutian Island chain, Alaska. The groundwater systems affected by the three underground nuclear tests at Amchitka Island are essentially unmonitored because all of the current monitoring wells are too shallow and not appropriately placed to detect migration from the cavities. The dynamics of the island`s fresh water-sea water hydrologic system will control contaminant migration from the three event cavities, with migration expected in the direction of the Bering Sea from Long shot and Cannikin and the Pacific Ocean from Milrow. The hydrogeologic setting (actively flowing groundwater system to maintain a freshwater lens) suggests a significant possibility for relatively rapid contaminant migration from these sites, but also presents an opportunity to use projected flowpaths to a monitoring advantage. The purpose of this investigation is to develop a conceptual model of the Amchitka groundwater system and to produce computer model simulations that reflect the boundary conditions and hydraulic properties of the groundwater system. The simulations will be used to assess the validity of the proposed conceptual model and highlight the uncertainties in hydraulic properties of the aquifer. The uncertainties will be quantified by sensitivity analyses on various model parameters. Within the limitations of the conceptual model and the computer simulations, conclusions will be drawn regarding potential radionuclide migration from the three underground nuclear tests
Recommended from our members
Chaotic-dynamical conceptual model to describe fluid flow and contaminant transport in a fractured vadose zone. 1998 annual progress report
'DOE faces the remediation of numerous contaminated sites, such as those at Hanford, INEEL, LLNL, and LBNL, where organic and/or radioactive wastes were intentionally or accidentally released to the vadose zone from surface spills, underground tanks, cribs, shallow ponds, and deep wells. Migration of these contaminants through the vadose zone has lead to the contamination of or threatens to contaminate underlying groundwater. A key issue in choosing a corrective action plan to clean up contaminated sites is to determine the location, total mass, mobility and travel time to receptors for contaminants moving in the vadose zone. These problems are difficult to solve in a technically defensible and accurate manner because contaminants travel downward intermittently through narrow pathways driven by variations in environmental conditions. These preferential pathways can be difficult to find and predict. The primary objective of this project is to determine if and when dynamical chaos theory can be used to investigate infiltration of fluid and contaminant transport in heterogeneous soils and fractured rocks. The objective of this project is being achieved through the following Activities (1) Evaluation of chaotic behavior of flow in laboratory and field experiments using methods from non-linear dynamics; (2) Evaluation of the impact these dynamics may have on contaminant transport through heterogeneous fractured rocks and soils, and how it can be used to guide remediation efforts; (3) Development of a conceptual model and mathematical and numerical algorithms for flow and transport, which incorporate both: (a) the spatial variability of heterogeneous porous and fractured media, and (b) the description of the temporal dynamics of flow and transport, which may be chaotic; and (4) Development of appropriate experimental field and laboratory techniques needed to detect diagnostic parameters for chaotic behavior of flow. This approach is based on the assumption that spatial heterogeneity and flow phenomena are affected by non-linear dynamics, and in particular, chaotic processes. The scientific and practical value of this approach is that the authors can predict the range within which the parameters of flow and transport change with time in order to design and manage the remediation, even when the authors can not predict the behavior at any point or time. This progress report summarizes work after 1.5 years of a 3-year project.