期刊
JOURNAL OF HYDROLOGY
卷 556, 期 -, 页码 813-823出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhydrol.2016.09.051
关键词
Periodically changing; Groundwater flow system; Stagnation point; Hydraulic head fluctuation; Zone with flowing wells
资金
- National Young Talents Support Program
- National Natural Science Foundation of China [41522205]
- Foundation for the Author of National Excellent Doctoral Dissertation [201457]
- Fundamental Research Funds for the Central Universities of China
Classical understanding on basin-scale groundwater flow patterns is based on Toth's findings of a single flow system in a unit basin (Toth, 1962) and nested flow systems in a complex basin (Toth, 1963), both of which were based on steady state models. Vandenberg (1980) extended Toth (1962) by deriving a transient solution under a periodically changing water table in a unit basin and examined the flow field distortion under different dimensionless response time, tau*. Following Vandenberg's (1980) approach, we extended Toth (1963) by deriving the transient solution under a periodically changing water table in a complex basin and examined the transient behavior of nested flow systems. Due to the effect of specific storage, the flow field is asymmetric with respect to the midline, and the trajectory of internal stagnation points constitutes a non-enclosed loop, whose width decreases when tau* decreases. The distribution of the relative magnitude of hydraulic head fluctuation, Delta h*, is dependent on the horizontal distance away from a divide and the depth below the land surface. In the shallow part, Delta h* decreases from 1 at the divide to 0 at its neighboring valley under all tau*, while in the deep part, Delta h* reaches a threshold, whose value decreases when tau* increases. The zones with flowing wells are also found to change periodically. As water table falls, there is a general trend of shrinkage in the area of zones with flowing wells, which has a lag to the declining water table under a large tau*. Although fluxes have not been assigned in our model, the recharge/discharge flux across the top boundary can be obtained. This study is critical to understand a series of periodically changing hydrogeological phenomena in large-scale basins. (C) 2016 Elsevier B.V. All rights reserved.
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