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- Title
Use of tree rings as indicator for groundwater level drawdown caused by tunnel excavation in Zhongliang Mountains, Chongqing, Southwest China.
- Authors
Zheng, Wei; Wang, Xiuli; Tang, Ya; Liu, Huang; Wang, Mei; Zhang, Lanjun
- Abstract
Tunnel excavation causes geological, hydrological, environmental and social changes. The effects of groundwater level changes caused by tunnelling on tree growth have been poorly understood. Dendrochronology was used to evaluate the impact of groundwater level drawdown on tree growth. Tree cores of Masson pines were collected from the areas affected by tunnel construction in the Zhongliang Mountains of Chongqing in south-western China to study the effects of tunnel excavation on the growth rate of trees by comparing with tree cores collected from unaffected areas. Excavation and early operation of the first tunnel in the Zhongliang Mountains from 1968 to 1984 caused a groundwater table drawdown in both karst aquifer and non-karst aquifer. The lowered groundwater table significantly reduced the growth rate of pine trees, and the low growth rate remained for 15 years. The effect was experienced up to at least 1 km from the tunnel axis. The decline in tree growth was higher in karst than in non-karst areas, though the effects on the trees of the karst areas were lagging. The high precipitation in 1998 contributed to groundwater recovery, after which the tree growth recovered moderately but not to the original level. Groundwater leakage of the recently excavated tunnels did not affect pine trees heavily, probably because the pines had adapted to the new hydrogeological conditions and new strategies in tunnel inflow management were adopted in the recently excavated tunnels. The use of tree growth rate as an indicator of groundwater table change in tunnelling areas offers a new option to study environmental impacts and the extent of tunnelling effects.
- Subjects
CHONGQING (China); TUNNEL design &; construction; GROUNDWATER; WATER leakage; EXCAVATION; TREE-rings; ECOLOGICAL impact; KARST
- Publication
Environmental Earth Sciences, 2017, Vol 76, Issue 15, p1
- ISSN
1866-6280
- Publication type
Article
- DOI
10.1007/s12665-017-6859-3