Preliminary Study on Early-warning System of Ecological Security in Water-Level-Fluctuating Zone (WLFZ) of Three Gorges Reservoir

The area,the scope as well as some ecological environment questions in Three Gorges Reservoir was briefly introduced. Then its early warning-system frame was preliminarily constructed,which includes ecological security dynamic monitoring,ecological security appraisal,ecological security forecast and ecological security decision-making management. The synthetic evaluation indicator system of the ecological security quality were initially established,which includes ecological environment pollution,land use and land cover change,geological hazard and epidemic outbreaks. At the same time,29 evaluating indicators were selected,divides into the basic factors,response factors and inducing factors,which need to be Real-time monitored.

Influence of the Repeated Flooding on Growth and Development of Acorus calamus Vegetation in Water-level-fluctuation Zone of the Three Gorges Reservoir

[ Objective] The research aimed to study influence of the repeated flooding on growth and development of A. calamus in water-level-fluc- tuation zone of the Three Gorges Reservoir. [ Method] A. calamus plants were exposed to water under the dark conditions respectively in Septem- ber 2009 and September 2010. Then, they were taken away from the water, and grew in natural conditions in the following March and April respec- tively （ marked as S1, S2, S1 and S2）. The plant number was conducted statistics respectively. On May 7, the leaf number was made statistics. Length, width and rapid light responding curve of the leaf were determined. [ Result] Repeated flooding restrained significantly plant germination un- der the dark condition. Plant number in S1 and S2 groups decreased by 38.9% and 33.3% respectively compared with the control. It also reduced survival rate of the plant. Plant number in S2 group decreased by 16.7% （P 〈 0.05） compared with that of S2 group when they were taken away from the water. Both of flooding promoted elongation of the leaves, restrained leaves to grow wider, and also restrained leaf formation of the plants except for S1 and S1 groups. Total leaf length of a plant decreased markedly after the second flooding which in S1 and S2 groups were 50.6% and 36.9% respectively less than that after the first flooding. Total leaf number of the plant in S1and S2 groups reduced significantly, and they were only 63.1% and 38.5% respectively of the control. Compared with the first flooding, total leaf length of a plant in the control increased signifi- cantly and decreased remarkably in S2 group after the second flooding. Furthermore, light response ability of the relative electronic transfer rate （rETR） in S1 group wasn＇t significantly different from the control, and rETRmax, in S2 group was significantly less than the control. Moreover, non- photochemical quenching （NPQ） decreased remarkably in S1 and S2 groups. It indicated that A. calamus had good restore ability of the light re- sponse, but restoring of its heat dissipation capacity was slower. [ Conclusion] Repeated flooding inhibited plant growth and population recovery of A. calamus under the dark condition.

Fractal characterization of sediment particle-size distribution in the water-level fluctuation zone of the Three Gorges Reservoir, China

The combined effect of periodic water impoundment and seasonal natural flood events has created a 30 m high water-level fluctuation zone(WLFZ) around the Three Gorges Reservoir(TGR), China, forming a unique eco-landscape. Siltation, eutrophication, enrichment of heavy metals, and methane emissions in the WLFZ have been widely associated with sediment and soil particles generated from the upstream catchment or upland slopes. However, little attention has been paid to the complexity of sediment particle-size distributions in the WLFZ. In the present study, core samples(from a 345 cm thick sediment core from the base of the WLFZ), slope transect surface samples(across/up a WLFZ slope), and along-river/longitudinal surface samples(from the reservoir reaches) were collected. Laser granulometry and a volume-based fractal model were used to reveal the characteristics of sediment particle-size distributions. Results indicate that the alternation of coarse and fine particles in the sedimentary core profile is represented as a fluctuation of low and high values of fractal dimension(D), ranging from 2.59 to 2.77. On the WLFZ slope transect, surface sediment particles coarsen with increasing elevation, sand content increases from 3.3% to 78.5%, and D decreases from 2.76 to 2.53. Longitudinally, surface sediments demonstrate a downstream-fining trend, and D increases gradually downstream. D is significantly positively correlated with the fine particle content. We conclude that D is a useful measure for evaluating sediment particle-size distribution.

The Main Ecological Issues of Water-Level -Fluctuating Zone and The strategies in Three Gorges Reservoir Area

After the completion of the Three Gorges dam, a 30 m high water-level-fluctuating zone （WLFZ） will appear along the banks, and will form a seasonal wetland ecosystem. According to the program of storing water in the Three Gorges reservoir, the main ecological and environmental problems probably incurred in WLFZ are discussed, such as formation of contaminated belt along banks, appearance of epidemic diseases in the reservoir region （including urban districts）, aggravation of geologic disasters, degradation of biodiversity and exacerbation of the ecosystem vulnerability. Six items of strategies are put forward according to the causes, distributed features and trends of these problems in this paper.

Estimation of soil reinforcement by the roots of four postdam prevailing grass species in the riparian zone of Three Gorges Reservoir, China

Soil erosion and bank degradation is a major post-dam concern regarding the riparian zone of the Three Gorges Reservoir. The development and succession of vegetation is a main countermeasure,especially to enhance bank stability and mitigate soil erosion by the root system. In this study, the roots of four prevailing grass species, namely, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, in the riparian zone were investigated in relation to additional soil cohesion. Roots were sampled using a single root auger. Root length density（RLD） and root area ratio（RAR） were measured by using the Win RHIZO image analysis system. Root tensile strength（TR） was performed using a manualdynamometer, and the soil reinforcement caused by the roots was estimated using the simple Wu＇s perpendicular model. Results showed that RLD values of the studied species ranged from 0.24 cm/cm3 to20.89 cm/cm3 at different soil layers, and RLD were significantly greater at 0–10 cm depth in comparison to the deeper soil layers（＆gt;10 cm）. RAR measurements revealed that on average 0.21% of the reference soil area was occupied by grass roots for all the investigated species. The measured root tensile strength was the highest for P. paspaloides（62.26MPa） followed by C. dactylon（51.49 MPa）, H.compressa（50.66 MPa）, and H. altissima（48.81MPa）. Nevertheless, the estimated maximum root reinforcement in this investigation was 22.5 k Pa for H.altissima followed by H. compressa（21.1 k Pa）, P.paspaloides（19.5 k Pa）, and C. dactylon（15.4 k Pa） at0–5 cm depth soil layer. The root cohesion values estimated for all species were generally distributed at the 0–10 cm depth and decreased with the increment of soil depth. The higher root cohesion associated with H. altissima and H. compressa implies their suitability for revegetation purposes to strengthen the shallow soil in the riparian zone of the Three Gorges Reservoir. Although the soil reinforcement induced by roots is only assessed from indirect indicators, the present results still useful for species selection in the framework of implementing and future vegetation recovery actions in the riparian zone of the Three Gorges Reservoir and similar areas in the Yangtze River Basin.

Protection and Ecological Restoration of Water Level Fluctuation Zone in the Three Gorges Reservoir

Water level fluctuation zone(hereinafter referred to as "WLFZ") is a transitional ecosystem between terrestrial ecosystem and aquatic ecosystem,and also a key area to control its neighboring terrestrial and aquatic ecosystem. After the Three Gorges Reservoir was put into use,ecological environment of its WLFZ has aroused wide concern from domestic and foreign experts. On the basis of introducing characteristics of WLFZ of the Three Gorges Reservoir,current ecological environment and main problems of this area were analyzed,plant selection and configuration was elaborated as well as the implementation effect of many WLFZ protection and ecological restoration modes. In view of the actual conditions,pertinent suggestions were proposed for WLFZ of the Three Gorges Reservoir,namely classified protection and ecological restoration,enhancing monitoring and assessment of current situation and change tendency,carrying out technical researches and demonstration of WLFZ wetland ecological restoration.

Ecosystem health evaluation system of the water-fluctuating zone in the Three Gorges Area

This paper discribes the definition of ecosystem health for the water-level flutuation zone of the Three Gorges Region and puts forward an evaluation system involving indicators in three groups: 1) structural indicators comprise slope, biodiversity, environmental capacity, stability, restoration ability and damage situation; 2) functional indicators including probability of geological hazard, erosion rate, habitat rate, land use intension and days of tourist season; 3) environmental indicatiors made up of population quality, potential intension of human, ground water quality, ambient air quality, wastewater treatment rate, pesticide use rate, fertilizer use rate, environmental management and public participation. In the design of the system, the subject zone is regarded as the type similar to wetland and the impacts of human activities on the zone are attached great importance to.

Spatial distribution,sources and ecological risk assessment of heavy metals in Shenjia River watershed of the Three Gorges Reservoir Area

Surface soil/sediment samples were collected from the Water-Level Fluctuation Zone(WLFZ), cultivated land and forest land at 50 different grid points from Shenjia watershed, the Three Gorges Reservoir area in August 2013. The spatial distribution, sources and ecological risk assessment for Arsenic(As), Cadmium(Cd),Chromium(Cr), Copper(Cu), Nickel(Ni), Lead(Pb)and Zinc(Zn) were analyzed in this study. The results showed all tested metals had similar distribution patterns except Ni and Cr, with areas of high concentrations distributed in the southwest(WLFZ and watershed outlet) of the study area. Ni and Cr,which were highly positively correlated and present in high concentrations, were primarily distributed in the south and middle zones of the study area. Lower concentration areas of all metals were uniformly distributed west of the high-elevation zones and forest land. Factor analysis(FA) and factor analysismultiple linear regression(FA-MLR) showed that the major sources of Cd were fertilizer and traffic sources,which together accounted for 87% of Cd. As, Zn and Cu levels were primarily supplied by industrial and domestic sources, accounting for 76% of As, 75% of Cu and 67% of Zn. Surface soils/sediments of the study watershed contaminated by Cd represent a high ecological risk, whereas other metals represent low ecological risks. The potential ecological risk index(PERI) analysis indicated that it had a low(widerange) ecological risk and a moderate(small-range)ecological risk primarily distributed in the outlet of the study watershed. Fertilizers and traffic are the primary sources of Cd pollution, which should be more closely controlled for the purposes of water quality and ecological conservation.

Malaria Transmission Potential in the Three Gorges Reservoir of the Yangtze River, China

Objective To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir. Methods Six villages, namely, Kaixian, Fengjie, Wanzhou, Fuling, Yubei, and Zigui were selected for investigating the malaria transmission potential in the reservoir. Transmission potential was estimated by mathematical modeling and evaluation of the local malaria situation. Factors that influenced the transmission potential were analyzed using Poisson regression analysis in combination with Grey Systematic Theory （based on evaluation by the Delphi method）. Results Indirect fluorescent antibody data and the incidence of malaria in the local population were consistent with the malaria transmission potential calculated for the area. Multivariate Poisson regression analysis showed a statistically significant association between the riparian zone and the man‐biting rate. Conclusion The risk of a malaria epidemic can be forecasted using the malaria transmission potential parameters investigated here which was closely correlated with the riparian zone.

A Study of the Crustal Stability in the Yangtze Three Gorges Area

The Three Gorges Dam on the Yangtze River is situated on the intact rock mass composed of diorite granite at the southern termination of the Huangling block which, as a sub plate with a double layer structure (crystalline basement and sedimentary cover) in the Chinese inland, keeps a constant but slow uplift as a whole since its formation in the Indoncisia movement. Tectonic deformation within the block is not significant, with the exception of a slight southeastward tilt. The block is confined by many active structures, of which the sub longitudinal Yuanan and Xiannvshan ( Mount Fairy ) deep fault zones are the main strongly seismogenic zones. The Yuan’an fault zone represents a regional boundary among West Henan, West Hubei and West Hunan mountainous regions as well as the Nanyang, Jianghan and Dongting Lake basins, with a total length of more than 1,000 km. Two M 6 5 earthquakes (in Changde and Nanyang) occurred in the fault zone in historic time and the distance between the two epicenters is about 500 km. The Mount Fairy fault zone extends northward along the Xiangxi River and ends at the Qingfeng fault. It runs a total length of more than 220 km. southward across Yuyang Pass and then its trace is unknown. The fault zone has a tectonic condition for occurrences of M 6.0 earthquakes. The possible seismic risk for the dam may come from these two strong seismogenic zones. Thus the seismic intensity to influence the dam is estimated to be Ⅵ～Ⅶ and the horizontal peak acceleration to be 0 1～0 15 g.

The fine velocity structure of sediment－base－ment layer in the Three－GorgesRegionoftheChangjiangRiver（YangtzeRiver）

In this paper, the study on the fine velocity structure of sedimental and basement layers along 4 deep seismic sounding profiles in the Three Gorges Region of the Changjiang River (Yangtze River) are presented. The velocity of sedimental cover is larger in hills of western Hubei in the western profiles, the total thickness is about 0～0.3 km. However, it becomes thick in southern part of Zigui basin and Zushui river valley, about 5.0 km and 4.0 km thick respectively. The sedimental cover is very thick in Jianghan plains in the eastern profiles, about 5～8 km, and the velocity is lower. The velocity of basemental plane is greater than 6.0 km/s over the whole region. An interface can be divided within the sedimental layer, it is about 3～4 km deep in Jianghan plains, while it approximates to surface in other regions. The profiles are cut by faults in many positions. Where the faults pass, the velocity isopleth varies sharply, and the velocity is obviously low. The basement layer is characterized by high velocity and low gradient, there exist 3 high velocity anomalous zones within the layer, which are located at the west, south and east of Huangling Anticlinorium respectively. They are the upwelling materials of basalt magma with high velocity from deep crust. Perhaps, this process took place before formation of Huangling Anticlinorium. Its action produces the significant variation of basement plane depth and the correspondent development and action of faults.

Effects of phosphorus fertilizer application rate on transformation processes of phosphorus fractions in the purple alluvial soil of a riparian zone

Effects of phosphorus(P)fertilizer application rate on soil transformation processes of P fraction are still unclear in the riparian zone.Purple alluvial soils in the riparian zone of the Three Gorges Reservoir were collected to conduct a 21-day incubation executed by two hydrological environments(drying and flooding)and ten application rates of P fertilizer.Transformation percentages of P fertilizer(TPPF)were calculated as content differences of soil P fractions between fertilizer addition and none fertilizer addition divided by soil total P increases caused by fertilizer addition.TPPF to inorganic P extracted by sodium hydroxide(NaOH-Pi)and hydrochloric acid(HCl-Pi)increase by 20.91%(9.71%)and 24.26%(40.72%)under the drying(flooding)environment.Instead,TPPF to the other fractions decrease.Phosphorus fertilizer input mainly has indirect positive and negative effects on organic P via precipitated P under the drying and flooding environments and finally has indirect positive effects on labile P(p<0.001).Percentage changes of water-soluble inorganic P(H2O-Pi)and HCl-Pi under the flooding environment are higher than that under the drying environment,and percentage changes of organic P extracted by sodium hydrogen carbonate(Na HCO3-Po)and NaOH-Pi show an opposite trend(p<0.01).?(differences in soil P fraction content between flooding and drying incubations)H2O-Pi is negatively correlated with?NaHCO3-Po,and?NaHCO3-Po is positively correlated with?NaOH-Pi(p<0.001).In conclusion,P fertilizer is transformed more into precipitated P than into other P fractions with an application rate increase.Phosphorus fertilizer input mainly increases organic P via precipitated P under the drying environment and decreases organic P via precipitated P under the flooding environment,and organic P is further transformed into labile P.With P fertilizer input,P release caused by flooding is derived from NaHCO3-Po release triggered by NaOH-Pi release.The results can be helpful for the understanding of P fertilizer migration processes from the riparian zone soil to the Three Gorges Reservoir under rain leaching and flooding.

周期性水位波动对三峡水库消落带土壤有机碳含量和密度的影响

为探究水位波动对三峡水库消落带土壤有机碳的影响,在三峡水库消落带采集和测定了受不同水淹强度影响的石灰土、紫色土、黄壤及其植物样品,并运用Kruskal-Wallis非参数检验和基于冗余分析的典范分析等方法进行了研究。结果表明:周期性水淹增加了石灰土和紫色土的有机碳含量和密度,但降低了黄壤的有机碳含量和密度。此外,石灰土的有机碳分布还受地上生物量、土壤pH和土层深度的影响,紫色土的有机碳分布还受土层深度和地上生物量的影响,而黄壤的有机碳含量和密度则与地上生物量、土层深度和地下生物量有关。总之,周期性水位波动对消落带土壤有机碳影响深刻,但土壤类型分异了有机碳对水位波动的响应。

三峡水库消落带土壤反硝化及DOM的影响

在重庆主城与涪陵选取了3个典型点位采集土壤样品,并对土壤的理化性质、原位反硝化速率、溶解性有机质(DOM)驱动的反硝化以及库区土壤的微生物进行了考察与分析.结果显示在海拔145~155m区间,淹水期镇安镇、涪陵区和鱼嘴镇最高氨氮(NH_(4)^(+)-N)平均浓度分别为31.32,28.63和19.23mg/kg,均高于落干期.在淹水期,与高海拔区域土壤中硝酸盐氮(NO_(3)^(-)-N)平均浓度相比,低海拔土壤中NO_(3)^(-)-N平均浓度分别增大了46.91%(镇安镇)、37.89%(涪陵区)和29.69%(鱼嘴镇).在淹水期,土壤有机质(SOM)平均浓度随着海拔高程的降低而降低,镇安镇、涪陵区和鱼嘴镇分别从109.16,80.93和82.61mg/kg降至65.63,64.53,53.41mg/kg.土壤中NH_(4)^(+)-N和NO_(3)^(-)-N的含量与现场反硝化速率呈显著正相关(P<0.05),在提供充足的碳(C)和氮(N)营养元素后,土壤潜在反硝化速率表现出较大的时间和空间差异性.在由DOM驱动的反硝化实验中,DOM降解符合一级动力学模型(R^(2)>0.93),N2O累积量符合Logistic模型(R^(2)>0.97).在三峡水库消落带土壤中,反硝化功能微生物主要是Bacillus和Comamonadaceae,其丰度变化与土壤潜在反硝化速率呈现显著的正相关性(P<0.05).

三峡水库消落带狗牙根根系对紫色土抗剪性能的影响

植物根系对提高土壤抗侵蚀能力起着最主要的作用。为探究根系对三峡水库消落带土壤抗剪性能的影响,以典型草本植物狗牙根及其根土复合体为研究对象,利用原状土和重塑土、采用直剪试验和三轴试验2种方法,揭示根系形态特征、含根量以及布根方式对土壤抗剪性能的影响。结果表明:1)内摩擦角、黏聚力与根系形态特征呈对数正相关;各形态指标对土壤抗剪性能的影响程度依次为:根表面积密度>根体积密度>根长密度>根质量密度>根径。2)根系含量与土壤抗剪性能呈正相关。含根量分别为0.9、0.6和0.3 mg/cm^(3)的根土复合体抗剪强度依次比素土提高14.54%~49.56%、9.09%~35.82%和3.80%~17.58%;内摩擦角依次提高13.95%、13.07%和1.98%;黏聚力依次提高29.37%、24.48%和15.34%。3)交叉布根下土壤抗剪性能最强,与垂直布根、水平布根相比,交叉布根的抗剪强度依次提高4.22%~16.95%和11.45%~32.61%;黏聚力依次提高15.61%和16.09%;最大应力值依次提高3.78%~34.18%和36.86%~41.44%。研究结果可为三峡水库消落带固土护岸的物种筛选、水土保持生态建设以及水库岸线管理等提供参考。

基于“微地形—植物”协同的三峡库区城市消落带修复设计与评估

微地形与植物的协同作用是自然河岸带生态系统维持结构稳定与生物多样性的重要机制。三峡库区蓄水后,其沿岸城市的原有河岸带转变为周期性淹没且水位落差极大的消落带,内部地形与植被破坏严重,生物多样性快速衰退,对库区城市的生态安全造成负面影响。选取重庆市开州区汉丰湖北岸的乌杨坝消落带,首次基于“微地形—植物”协同提出消落带生态系统修复设计技术框架,并对修复后的消落带微地形、植物群落和鸟类群落进行调查分析,评估修复设计的实际效果。结果表明:丰富的微地形类型及其组合有效促进了乌杨坝消落带的植物多样性恢复;二者耦合作用,在不同水位条件下维持了鸟类生境异质性,使鸟类多样性得到提升。因此,“微地形—植物”协同设计有助于维持三峡水库消落带生态系统的结构稳定性及生物多样性,有利于生态服务功能的保障及发挥。

基于Markov模型的三峡上游消落带土地利用变化预测

三峡水库蓄水后形成高程差30 m的消落带,以蓄满水位175 m为基准水平外扩150 m得到交错缓冲区。缓冲区土地利用情况较复杂,本研究通过研究库区上游缓冲区近20年土地利用的变化情况,分析前20年上游发展模式。通过马尔可夫函数来预测未来20年的土地利用变化可能,为上游区域未来规划发展方向提出建议。研究表明:(1)上游在发展过程中持续紧抓农业用地,可按目前的模式继续发展;(2)生态方面,森林、灌丛、草地等与生态环境相关的地类占比是有所提高的,目前发展政策是有利生态环境的,但由于水域面积增长导致裸岩增加,水土流失风险增加,需更加重视水土流失的防治;(3)经济发展与城镇化密切相关,城乡建设用地与道路占比不断上升,上游经济形势一片大好。综合来说,可按照2000~2020年的发展模式继续开发建设,但应在此基础上更加重视经济与环境的协同发展,尽量建设森林城市,通过工程护坡、生态护坡等技术来加强两岸土地的水土保持力度。

适应水位变化的三峡库区消落带碳汇提升设计及效益评估

【目的】三峡库区消落带受周期性的水位涨落及冬季长时间深水淹没影响,碳汇能力遭受严重破坏。如何恢复并充分发挥消落带生态系统的碳汇潜力,成为三峡库区生态治理的关键议题。【方法】针对复杂水位变化挑战,提出以林塘模式修复消落带生态系统并提升碳汇能力的技术框架,选取位于三峡库区腹心的大浪坝消落带开展实证研究。运用CASA模型测算修复前后大浪坝消落带的净初级生产力(net primary productivity,NPP),基于植被生物量数据计算修复后大浪坝消落带与未修复对照组内不同高程带的碳汇能力,评估林塘碳汇系统的可持续效益。【结果】修复后大浪坝消落带的碳汇能力随时间推移明显提升,NPP由2012年的154.4 g C·m^(2)·a^(-1)增长至2016年的182.5 g C·m^(2)·a^(-1);各高程带的碳汇能力均显著高于对照组,并呈现出随海拔降低而减弱的趋势,170~175 m高程带碳汇能力达到1.827 kg C/m^(2),160~165 m高程带碳汇能力仅为0.830 kg C/m^(2)。林塘系统增强了生态系统的适应性和复原力,形成了适应水位变化的立体固碳模式并有效提升了碳汇效率。【结论】林塘碳汇系统是应对三峡库区复杂水位变化和长时间深水淹没挑战的适应性探索,显示出景观优化、生物多样性、经济效益与碳汇协同耦合的关键特征。研究成果能够为中国大型工程型水库消落带的治理及碳增汇提供科学依据与可复制推广的创新技术模式。

基于分形理论的三峡库区消落带岸线形态特征研究

以消落带为基础数据,采用网格法计算了不同水位及各段岸线的分形维数,对其分布特征和空间分布规律进行了研究。结果表明:(1)145 m水位岸线、175 m水位线和消落带整体形态的分维值D分别为1.1996,1.3216,1.3192;(2)消落带145 m水位线相对于175 m水位线和消落带整体形态而言,相对平直简单,与岸线实际情况相符合;(3)消落带网格单元分维值整体均值为1.24,最大值为1.40,主要分布在1.05~1.3之间。

滨水消落带植物景观设计初探——以三峡库区滨水消落带项目总结为例

步入21世纪,中国经济处于高速发展,但环境污染、生态系统退化问题却日趋严重。十八大、十九大相继提出生态文明建设的国家战略,社会可持续发展的生态安全观念也有所提升。但当前滨水生态安全问题依然严峻,其中,由于滨水消落带涉及的范围广,每年导致的生态破坏与经济损失尤为巨大,目前行业内治理措施与专项技术相对滞后,缺乏较为成功的实际案例作为技术借鉴。论文结合三峡库区苦溪河部分河段滨水消落带综合整治项目作为案例研究,结合设计专项技术与实施经验总结,为今后日趋严重的滨水消落带综合治理问题提供一定的技术支持与经验借鉴意义。