碩士 / 國立中興大學 / 水土保持學系所 / 101 / Tide-induced water table fluctuations in coastal aquifers have a great impact on biological activities, chemical transformations and coastal sediment erosions.
The data of groundwater level changes are usually obtained by the groundwater observation wells. It is not easy to dig wells in the steep terrain or remote areas and also it costs a lot. Understanding water table fluctuations in coastal aquifers can provide the correct prediction and management.
The Boussinesq equation is usually employed to govern the flow in coastal aquifers. The traditional Boussinesq equation supposes that the impervious bed is flat. Before this study, there are a number of scholars using this equation to deduce analytical solutions of different stratigraphic situations. (e.g., the problem of inclined coastal slope, the leakage phenomenon of aquifers). Impervious beds within the coastal aquifers may be inclined because of squeezing ground. For this phenomenon, the study employed the Chapman’s (1980) modified Boussinesq equation to govern the flow in coastal aquifers and solved it by the perturbation method. Then, second-order nonlinear solutions were obtained.
This study added the change of the inclined angle of the impervious bed,and then the groundwater level fluctuations varying with time and space in different slopes angle and impervious bed angles were discussed. When the impervious bed is flat, this study compared with the previous nalytical solutions and the indoor experimental data, the results are in a good agreement. With the change of impermeable bed angle, the larger the inclined angle, the larger the
downward vibration of groundwater level. But the downstream groundwater level will gradually become smaller. It is also found that if the impervious bed slopes downward, the inclined angle between -25 ° ~ -35 °, the downstream
groundwater level will first rise and then descend.
As to the two-dimensional analytical solutions, the impact of river water level fluctuations was investigated. When the impervious bed slopes upward, the angle greater than 10 °, it will increase the frequency of groundwater level fluctuations. When the impervious bed slopes downward, the influence of the river water level fluctuations will increase the downward vibration of groundwater level, but the downstream groundwater level will decrease.
| Identifer | oai:union.ndltd.org:TW/101NCHU5080002 |
| Date | January 2013 |
| Creators | Huei-Ru Shiau, 蕭惠如 |
| Contributors | Ping-Cheng Hsieh, 謝平城 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 66 |
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