碩士 / 國立中央大學 / 應用地質研究所 / 98 / The behavior of Seawater intrusion in coastal aquifers is controlled mainly by the aquifer heterogeneity and the natural complexity of aquifer systems such as aquifer geometries, tidal fluctuation, aquifer saturation, and recharges of the aquifer. To systemically quantify such effects on the seawater-freshwater interface in coastal aquifers, this study employs the FEMWATER numerical model, combining Monte Carlo Simulation and Sequential Gaussian Simulation (SGSIM) random field generator, which built in Geostatistical Software Library (GSLIB), to simulate the two-dimensional seawater intrusion procedures in estuary aquifers. A profile estuary aquifer with 400m in length and 100m in depth is considered in the illustrated examples. The hydraulic conductivity fields of the aquifer are generated by SGSIM. Monte Carlo simulations with different degrees of aquifer heterogeneity, including lnK variance= 0.1, 0.5, 1.0, and 1.5, are used to obtain the concentration variation of the seawater-freshwater interfaces. The uncertainty bandwidths of seawater-freshwater interfaces can be obtained based on the defined seawater-freshwater interface of 0.1g/L. Besides the effects of different degrees of aquifer heterogeneity, this study also discusses the influence of five coastal aquifer scenarios (saturated aquifer, unsaturated aquifer, tidal aquifer, recharged aquifer and sloping aquifer) on the uncertainty bandwidths. Simulation results show that the spatial variation of hydraulic conductivity can propagate to flow uncertainties and then change the distributions of saltwater concentration significantly in saturated estuary aquifers. With different degrees of aquifer heterogeneity, the distances of the seawater/ freshwater interfaces vary from meters to tens of meters. Simulation results also show that aquifer geometries and aquifer saturation have significant impact on the patterns of seawater-freshwater interfaces. However, the recharge, and the fluctuation of tidal boundaries have relatively small influence on the variation of seawater-freshwater interfaces.
| Identifer | oai:union.ndltd.org:TW/098NCU05503041 |
| Date | January 2010 |
| Creators | Wei-ci Li, 李唯祺 |
| Contributors | Chuen-fa Ni, 倪春發 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 77 |
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