HR: 1340h
AN: H13B-0408    [Abstracts]
TI: Uncertainty Analysis in Identifying the Source Location and Release History
AU: * Lin, Y
EM: murphy.ev89g@nctu.edu.tw
AF: Institute of Environmental Engineering, National Chiao Tung Unversity, No. 75, Po-Ai Street, Hsinchu, 300 Taiwan
AU: Yeh, H
EM: hdyeh@mail.nctu.edu.tw
AF: Institute of Environmental Engineering, National Chiao Tung Unversity, No. 75, Po-Ai Street, Hsinchu, 300 Taiwan
AB: In the real world, in case a high contaminant concentration plume is detected at monitoring wells, the source characters such as source location and release history are needed to be identified. The engineers need to evaluate an appropriate management or remediation strategy based on the information of source characters. The method of locating the source and determining the release history is an inverse problem and may be called as source identification. The groundwater contaminant source identification is an ill-posed problem since the contaminant fate and transport processes are irreversible. In this study, a method is developed using the simulated annealing (SA) incorporated with a two-dimensional transport model to determine the source characters containing the release magnitude and the release time. The proposed method minimizes the sum of square errors between the simulated concentrations and sampling concentrations at the monitoring wells. A hypothetical case is assumed to demonstrate the capability of the proposed method in identifying the contaminant source characters. Assume that a point source is injected instantaneously into the aquifer twice at unknown location and times. With the sampling concentrations, the proposed method is used to determine the source characters. The hydrogeologic parameters such as groundwater velocity and dispersion coefficient are the essential information in the work of source identification. The main objective of this study is to perform the sensitivity analysis for the parameters of seepage velocity and dispersion coefficient in identifying the source location and release history. In addition, different values of initial temperature are also used to examine the stability of SA. The results of sensitivity analysis for the initial temperature indicate that SA yields almost the same identification results when using different initial temperatures. In the sensitivity analysis for the parameters of seepage velocity and dispersion coefficient, the source location is more insensitive to the change of longitudinal dispersion coefficient than those of the seepage velocity and transverse dispersion coefficient. However, the release history is very sensitivity to the changes of longitudinal and transverse dispersion coefficients due to the fact that conceptually the dispersion spreads the contaminant in longitudinal and transverse directions at the advection front. In short, the results show that the estimated source location and release history are more sensitivity to the variation of dispersion coefficient than that of groundwater velocity.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1832 Groundwater transport
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting