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| Titel |
Evolution of Unsteady Groundwater Flow Systems |
| VerfasserIn |
Xing Liang, Menggui Jin, Hong Niu |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130363
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| Publikation (Nr.) |
 EGU/EGU2016-10610.pdf |
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| Zusammenfassung |
| Natural groundwater flow is usually transient, especially in long time scale. A theoretical
approach on unsteady groundwater flow systems was adopted to highlight some of the
knowledge gaps in the evolution of groundwater flow systems. The specific consideration was
focused on evolution of groundwater flow systems from unsteady to steady under natural and
mining conditions. Two analytical solutions were developed, using segregation variable
method to calculate the hydraulic head under steady and unsteady flow conditions. The
impact of anisotropy ratio, hydraulic conductivity (K) and specific yield (μs) on the
flow patterns were analyzed. The results showed that the area of the equal velocity
region increased and the penetrating depth of the flow system decreased while the
anisotropy ratio (ɛ = ∘Kx-∕Kz--) increased. Stagnant zones were found in the flow field
where the directions of streamlines were opposite. These stagnant zones moved up
when the horizontal hydraulic conductivity increased. The results of the study on
transient flow indicated a positive impact on hydraulic head with an increase of
hydraulic conductivity, while a negative effect on hydraulic head was observed when
the specific yield was enhanced. An unsteady numerical model of groundwater
flow systems with annual periodic recharge was developed using MODFLOW. It
was observed that the transient groundwater flow patterns were different from that
developed in the steady flow under the same recharge intensity. The water table
fluctuated when the recharge intensity altered. The monitoring of hydraulic head and
concentration migration revealed that the unsteady recharge affected the shallow
local flow system more than the deep regional flow system. The groundwater flow
systems fluctuated with the action of one or more pumping wells. The comparison
of steady and unsteady groundwater flow observation indicated that the unsteady
flow patterns cannot be simulated by the steady model when the condition changes
frequently.
This study was financially supported by National Natural Science Foundation of China
(U1403282 & 41272258). |
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