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Shankman D.,University of Alabama | Keim B.D.,Louisiana State University | Nakayama T.,Center for Global Environmental Research | Li R.,Jiangxi Institute of Water science | And 2 more authors.
Earth Interactions | Year: 2012

Poyang Lake in Jiangxi Province is the largest freshwater lake in China and is historically a region of significant floods. Maximum annual lake stage and the number of severe flood events have increased during the past few decades because of levee construction that reduced the area available for floodwater storage. The most severe floods since 1950 occurred during 1954, 1973, 1983, 1995, and 1998. Each of these floods followed El Niño events that influence the Asian monsoon and that are directly linked to rainfall in the Changjiang (Yangtze River) basin. The 1954 flood was the largest ever recorded until the 1990s. That year the peak Changjiang stage at Hukou was 21.6 m, which was 1.6 m above the previous record high. The last major flood on the Changjiang was during 1998, when the peak Changjiang stage reached 22.5 m, higher than during 1954, even though peak discharge was lower. The most severe floods, including those in 1954 and 1998, require both 1) high rainfall and tributary discharge into Poyang Lake and 2) high Changjiang discharge and stage at Hukou that backflows into the lake or slows Poyang Lake drainage. Since gauging stations were established on the Changjiang, these conditions always occurred following an El Niño. Source

Wang F.L.,Jiangxi Institute of Water science | Hu W.,Jiangxi Flood Control and Drought Relief Headquarters office
Applied Mechanics and Materials | Year: 2014

According to researches on mechanism and concept of off-stream ecological water demand, off-stream ecological water demand of Fu River Basin is consist of ecological water demand for soil and water conservation and for urban public green space, considering the current situation and planning objectives of off-stream ecological water demand of Fu River Basin. Directly calculation method is employed in this study. Choosing 2005 as the current year in this study, indicators of public green space and soil erosion data are obtained. Then the ecological water demand of urban public green space in Fuzhou City is determined as 0.438×108m3 and the water demand for off-stream soil and water conservation in Fu River Basin is determined as 0.3159×108m3 in virtue of quota method. The off-stream ecological water demand in the Basin (2005 as the current year) is about 0.359×108m3. The determination of the off-stream ecological water demand in the basin provide a scientific basis on taking a variety of water-saving measures, improving the recovery rate of sewage treatment and increasing the off-stream ecological water consumption. Results of this study will make the ecological environment of this area to achieve a healthy state, and shall greatly improve regional water resources and water environmental situation. © (2014) Trans Tech Publications, Switzerland. Source

Yuan G.,CAS Wuhan Institute of Hydrobiology | Yuan G.,University of Chinese Academy of Sciences | Cao T.,CAS Wuhan Institute of Hydrobiology | Cao T.,University of Aarhus | And 8 more authors.
Freshwater Biology | Year: 2013

Strategies of carbon (C) and nitrogen (N) utilisation are among the factors determining plant distribution. It has been argued that submersed macrophytes adapted to lower light environments are more efficient in maintaining C metabolic homeostasis due to their conservative C strategy and ability to balance C shortage. We studied how depth distributions of 12 submersed macrophytes in Lake Erhai, China, were linked to their C-N metabolic strategies when facing acute NH4 + dosing. NH4 + dosing changed C-N metabolism significantly by decreasing the soluble carbohydrate (SC) content and increasing the NH4 +-N and free amino acid (FAA) content of plant tissues. The proportional changes in SC contents in the leaves and FAA contents in the stems induced by NH4 + dosing were closely correlated (positive for SC and negative for FAA) with the colonising water depths of the plants in Lake Erhai, the plants adapted to lower light regimes being more efficient in maintaining SC and FAA homeostasis. These results indicate that conservative carbohydrate metabolism of submersed macrophytes allowed the plants to colonise greater water depths in eutrophic lakes, where low light availability in the water column diminishes carbohydrate production by the plants. © 2013 The Authors. Freshwater Biology published by John Wiley & Sons Ltd. Source

Li Y.,Hohai University | Zhao J.,Hohai University | Lyu H.,Jiangxi Institute of Water science | Chen B.,Jiangxi Institute of Water science
Shuikexue Jinzhan/Advances in Water Science | Year: 2016

The hyporheic layer is an important part of riparian zones. To reveal the distribution of temperature and flow field of hyporheic layers in riparian zones under the influence of low temperature water, a real-time monitoring test of temperature and water level was used to study the thermal structure of a hyporheic layer in different seasons and spatial locations, which could be used to calculate the groundwater velocity. Our results show that the temperature field of the hyporheic layer is characterized by seasonal reversal of thermal stratification: surface-warm and deep-cold during the summer and surface-cold and deep-warm during the winter. Among the four methods of calculation of the groundwater flow using temperature tracer, the Hatch phase method yielded the highest accuracy. The flow velocities ranged from 1.03×10-4 to 7.96×10-4m/s during the period of Dec. 15-31, 2014, which decreased with the increasing depth in section and the groundwater flow velocity curves were close to parallel. © 2016, Editorial Board of Advances in Water Science. All right reserved. Source

Fu H.,CAS Wuhan Institute of Hydrobiology | Fu H.,Jiangxi Institute of Water science | Yuan G.,CAS Wuhan Institute of Hydrobiology | Yuan G.,University of Chinese Academy of Sciences | And 4 more authors.
PLoS ONE | Year: 2013

Although functional trait variability is increasingly used in community ecology, the scale- and size-dependent aspects of trait variation are usually disregarded. Here we quantified the spatial structure of shoot height, branch length, root/shoot ratio and leaf number in a macrophyte species Potamogeton maackianus, and then disentangled the environmental and ontogenetic effects on these traits. Using a hierarchical nested design, we measured the four traits from 681 individuals across five ecological scales: lake, transect, depth stratus, quadrat and individual. A notable high trait variation (coefficient variation: 48-112%) was observed within species. These traits differed in the spatial structure, depending on environmental factors of different scales. Shoot height and branch length were most responsive to lake, transect and depth stratus scales, while root/shoot ratio and leaf number to quadrat and individual scales. The trait variations caused by environment are nearly three times higher than that caused by ontogeny, with ontogenetic variance ranging from 21% (leaf number) to 33% (branch length) of total variance. Remarkably, these traits showed non-negligible ontogenetic variation (0-60%) in each ecological scale, and significant shifts in allometric trajectories at lake and depth stratus scales. Our results highlight that environmental filtering processes can sort individuals within species with traits values adaptive to environmental changes and ontogenetic variation of functional traits was non-negligible across the five ecological scales. © 2013 Fu et al. Source

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