Influence of Water Level on Cynodon dactylon Population in Water-Level-Fluctuating Zone of the Three Gorges Reservoir

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.295-298.1857 ◽

2013 ◽

Vol 295-298 ◽

pp. 1857-1861

Author(s):

Qiang Li

Keyword(s):

Water Level ◽

Three Gorges Reservoir ◽

Cynodon Dactylon ◽

Stem Length ◽

Three Gorges ◽

Node Number ◽

The Three Gorges Reservoir ◽

The Three Gorges ◽

Water Level Changes ◽

Influence Of Water

To research influence of water level changes on vegetations restoration in water-level-fluctuating zone of the Three Gorges Reservoir, Cynodon dactylon in Changshou area was respectively investigated in 2008 and 2009. The results show that germination rate in 2009 is 45.3% lower than that in 2008. Total rhizome length and total node number of rhizomes in 2009 significantly increase by 303.5% and 411.1%, respectively. However, stem length, node number, leaf width and leaf number of ramets decrease by 60.1%, 55.1%, 28.6% and 33.8%, respectively. Meanwhile, total buds number, germinated buds number and buds number to rhizome length ratio in 2009 increase by 500.7%, 228.5% and 50.9%, respectively. Compared with 2008, fresh mass of ramats, rhizomes and roots reduce respectively 65.6%, 23.4% and 70.0%, and their dry mass reduce respectively 65.9%, 18.8% and 64.5%. Therefore, water level changes accelerate rhizomes extension and the formation of buds and ramets, and inhibite ramets growth.

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Dynamics of Mid-Channel Bar during Different Impoundment Periods of the Three Gorges Reservoir Area in China

Water ◽

10.3390/w13233427 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3427

Author(s):

Qingqing Tang ◽

Daming Tan ◽

Yongyue Ji ◽

Lingyun Yan ◽

Sidong Zeng ◽

...

Keyword(s):

Water Level ◽

Three Gorges Reservoir ◽

Hydrological Regime ◽

Temporal Variations ◽

Three Gorges Reservoir Area ◽

Three Gorges ◽

The Three Gorges Reservoir ◽

The Three Gorges ◽

Water Level Changes ◽

Influence Of Water

The dynamics of the mid-channel bars (MCBs) in the Three Gorges Reservoir (TGR) were substantially impacted by the large water-level changes due to the impoundments of the TGR. However, it is still not clear how the morphology of the MCBs changed under the influence of water level and hydrological regime changes induced by the impoundments and operation of the TGR. In this work, the MCBs in the TGR were retrieved using Landsat remote sensing images from 1989 to 2019, and the spatio-temporal variations in the number, area, morphology and location of the MCBs during different impoundment periods were investigated. The results showed that the number and area of MCBs changed dramatically with water-level changes, and the changes were dominated by MCBs with an area less than 0.03 km2 and larger than 1 km2. The area of MCBs decreased progressively with the rising water level, and the number generally showed a decreasing trend, with the minimum number occurring at the third stage when the water level reached 139 m, resulting in the maximum average area at this period. The ratio of length to width of the MCBs generally decreased with the changes in hydrological and sediment regimes, leading to a shape adjustment from narrow–long to relatively short–round with the rising of the water level. The water impoundments of the TGR led to the migration of the dominant area from the upper section to the middle section of the TGR and resulted in a more even distribution of MCBs in the TGR. The results improve our understanding of the mechanisms of the development of MCBs in the TGR under the influence of water impoundment coupled with the annually cyclic hydrological regime and longer periods of inundation and exposure.

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