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Water temperature is a fundamental parameter for both hydrological and ecological processes in aquatic systems. Usually, a sinusoidal function is used to represent the seasonal variation of water temperature in natural surface water. However, a large number of dams have been built on rivers worldwide, and water mass transport is retarded due to the reservoir impoundment. As a result, the water temperature lags seasonally behind the natural cycle due to seasonal dam‐operation, and the ordinary sinusoidal function is no more valid in describing the thermal process. In this study, a composite cosine function (CCF) is introduced to address the dam‐influenced seasonally varying water temperature pattern, which includes a time varying phase‐lag for temperature variations. The proposed method is applied to the Three Gorges Reservoir (TGR), a major impoundment on the Yangtze River, China. It is found that the annual thermal process of warming and cooling becomes asymmetry during the post‐TGR stage, that is, the seasonally varying temperature follows an asymmetric sinusoidal wave pattern. In frequency spectrum, both annual and semi‐annual components are main contributors to the time varying water temperature. The minimum temperature of TGR's discharge has increased by 1.86°C after the normal operation of the reservoir, and the coldest water arrival timing is postponed by up to 40 days in the dry season. The benefit of using CCF in temperature reconstruction is that it can prevent the mistake of ascribing the semi‐annual component to short‐term fluctuations. The present study can help in improving the understanding of the asymmetric seasonal temperature processes due to dam operation.

Since the operation of the Three Gorges Reservoir, its tributaries have been eutrophic and flooded many times, the prompt and accurate eutrophication assessment is the foundation of water environmental management for this area. To address the problems existing in the fuzzy comprehensive evaluation, a novel method is proposed to adjust the indicator weight by using the analytic hierarchy process-entropy weight method, improve the fuzzy operation method, and take the weighted average as the basis of comprehensive evaluation. Through this method, the information of each indicator can be comprehensively used, and the subjectivity and blindness of evaluation can be effectively reduced. Then the eutrophication status of Hanfeng Lake is analyzed by it, and compares the results with that of conventional methods. The results show that Hanfeng lake is greatly affected by TN and TP, and it is generally in mesotrophic to mildly eutrophication. Eutrophication degree is as follows: Nanhe River > Donghe River > Regulating dam, so the control measures should be strengthened in Nanhe area. Combined with the water pollution control measures proposed in this paper, it can provide guidance for the monitoring and treatment of eutrophication in the Three Gorges Reservoir area and ensure the safety of the water environment. PRACTITIONER POINTS: This paper proposes to use the analytic hierarchy process-entropy weight method combined with the fuzzy operation method to assess the eutrophication status of tributaries of the Three Gorges Reservoir, in China. The results indicate that Hanfeng Lake is generally in a light eutrophication state, which is greatly affected by TN and TP, and the Nanhe River is in a relatively high degree of eutrophication, which need to be extra vigilant. The evaluation results are more conformable to reality than that of the traditional fuzzy comprehensive evaluation, which can provide guidance for comprehensive management of eutrophication.

The Three Gorges Dam (TGD) has altered downstream flow-sediment regimes and led to significant changes in the morphodynamic processes in the Middle Yangtze River (MYR). However, due to the complexity of this large river, the driving forces and implication of the morphodynamic processes remain insufficiently understood. This study selected two typical meandering and bar-braided reaches, the Zhicheng (ZC) and Shashi (SS) reach, to examine their responses to the TGD operation. The results showed that in the post-dam period significant channel erosion occurred with a higher erosion rate in the ZC reach (closer to the TGD) compared with the SS reach. The area of the Guanzhou mid-channel bar (ZC reach) and the Sanba mid-channel bar (SS reach) shrank by 30 and 90% from 2003 to 2015, respectively. The increased fluvial erosion intensity due to the reduction in suspended sediment concentration (SSC) drove the shrinkage of the mid-channel bars, as demonstrated by empirical relationships between bar geometry and fluvial erosion intensity. An increase of 22 days per year in the frequency of post-dam medium-to-high discharges (10 000-25 000 m(3) s(-1)), and associated with the reduction in SSC, jointly led to the greater erosion at the convex (inner) banks than the concave (outer) banks, which has negatively affected the designed navigation channels at the concave banks by decreasing their discharge partitioning ratios. The post-dam water level at a given high discharge (>25 000 m(3) s(-1)) showed no evident change, but the water level at a given low discharge (

Dam cascades have been a major threat to fishes of the upper Yangtze River. The remaining lotic river segment of the upper mainstem between the Xiangjiaba Dam (XJD) and the Three Gorges Reservoir (TGR) may serve as a critical refuge for endemic fishes. We investigated distribution of ichthyoplankton Botia superciliaris, an endemic species, at three sections preimpoundment and postimpoundment of the XJD, that is, Yibin (close to the XJD), Zhuyang (in the middle of the segment), and Mudong (in the tail of the TGR). Preimpoundment of the XJD, larvae occurred in all three sections, and their abundance tended to be highest at Yibin and lowest at Mudong. Postimpoundment, larval abundance dramatically decreased in all three sections. In particular, no larvae were found at Yibin, and larval abundance tended to be higher at Zhuyang than at Mudong. Eggs were collected from all three sections, and those from Zhuyang accounted for over 90% of the total. Initiation of egg occurrence at Yibin was approximately 1 month later than at Zhuyang and Mudong. Water temperature was lower, and water transparency was higher at Yibin than at Zhuyang and Mudong postimpoundment. We suggest that the decrease in abundance and delayed presence of ichthyoplankton at Yibin postimpoundment of the XJD reflected the impact of upstream dam discharge and that the lower abundance of ichthyoplankton at Mudong compared with Zhuyang both preimpoundment and postimpoundment of the XJD reflected the influence of inundation by the TGR. We recommend that the river sections around Zhuyang become high-priority conservation areas

Consecutive rainfall events (CREs) are important triggers of geological hazards like landslide downhill and mudslide in the Three Gorges Reservoir area (TGR), China. These hazards are not only potential risks for the effective storage capacity of the reservoir but also threats of the safety of the reservoir's Great Dam. The future changes of CREs' occurrence and intensity are analyzed by using the projection experiments from 20 models attending the Coupled Model Intercomparison Project Phase 5 (CMIP5) under three different representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5). Spring and fall are focused on, during which CREs are most frequent. Considering a common overestimate of rainy days number in the state‐of‐the‐art models, a new approach is developed to define CREs based on the percentile of rainfall distribution in observations. The approach yields a similar CREs climatology in models to that in observations and thus is used to identify CREs in models. The results based on multiple model ensemble (MME) and model spread comparison suggest a significant increase in spring and an overall decrease in fall in CREs' occurrence under all three scenarios. As for the intensity, it is projected to intensify in both spring and fall. Particularly, the higher the emission scenario, the greater the spring accumulated rainfall amount during a single CRE. These results imply an increasing risk of geological hazards in the TGR in the future.

With the completion of the Three Gorges Dam, soils between the elevations of 145 and 175 m are exposed or submerged seasonally. Soil hydrological and physical properties are changed. A detailed investigation was performed to examine the influence of the timing of inundation on soil physical quality. Samples were collected in the water level fluctuation (WLF) zone and non-WLF zone in Zhongxian County, Chongqing. Soil samples were taken from depths of 0 to 10, 10 to 20, 20 to 30, and 30 to 40 cm. Soil structural quality was assessed by the visual evaluation of soil structure (VESS) method in situ; mean weight diameter (MWD and mass fractal dimension () were measured to represent soil aggregate stability; and the soil water retention curve and computed microtomography (micro-CT) images were used to show soil pore networks. Our findings show a deterioration of soil structure indicated by a high structural quality (Sq) score in VESS (the higher the Sq score, the worse the soil structural quality) and a decline in soil aggregate stability indicated by low MWD and low in the WLF zone. The data from both the soil water retention curve and micro-CT images demonstrate a deterioration of soil physical quality through decreased porosity and a shift of drainable micropores (0.1 < radii < 125 μm) to non-drainable micropores (radii < 0.1 μm) in the WLF zone of the Three Gorges Reservoir. The potential of environmental hazards of soil in WLF zone was also investigated.

In this study, water temperature longitudinal and temporal patterns were investigated in four locations of the Yangtze River to identify their influence on spawning of the Chinese sturgeon (Acipenser sinensis Gray 1835). The results showed that, historically (1960–1980), the four locations, Pingshan (PS, 2,687 river kilometres [rkm]), Yichang (YC, 1,640 rkm), Chenglingji (CLJ, 1,265 rkm), and Hukou (HK, 805 rkm), all had similar average annual water temperatures (around 18.0 °C) but very different amplitudes: The upper two locations, PS (11.4–23.2 °C) and YC (9.1–25.9 °C), were relatively stable and had smaller amplitude than the lower two ones, CLJ (6.0–30.0 °C) and HK (5.9–30.8 °C). On the basis of the physiological effects for Chinese sturgeon, we defined three water temperature ranges: stressing (>23 °C), holding (23–20 °C), and spawning (20–16 °C). We found that the upper two locations with successful spawning of the Chinese sturgeon (PS and YC) had short or no stressing period but long holding and spawning periods. Currently (2013–2016), the impoundment of the Three Gorges Reservoir increases the time for water temperature decreasing to 20 °C at the current spawning ground (YC) in autumn, which increases the stressing and holding periods, and has significant negative impact on the spawning of Chinese sturgeon. Nonetheless, considering the very high stressing temperature and the short duration of the holding and spawning periods at CLJ and HK, we propose that YC is still the most suitable spawning location for the Chinese sturgeon.

Comparisons of flow time series between preimpact and postimpact periods have been widely used to determine hydrological alterations caused by reservoir operation. However, preimpact and postimpact periods might also be characterized by different climatological properties, a problem that has not been well addressed. In this study, we propose a framework to assess the cumulative impact of dams on hydrological regime over time. The impacts of the Three Gorges Dam (TGD) on the flow regime of the Yangtze River were investigated using this framework. We reconstructed the unregulated flow series to compare with the regulated flow series during the same period (2010 to 2015). Eco-surplus and eco-deficit and the Indicators of Hydrologic Alteration (IHA) parameters were used to examine hydrological regime change. Among 32 IHA parameters, Wilcoxon signed-rank test and principal component analysis identified the October median flow, 1- and 3-day maximum flows, 1-day minimum flow, and rise rate as representative indicators of hydrological alterations. Eco-surplus and eco-deficit showed that the reservoir also changed the seasonal regime of the flows by reducing autumn flow and increasing winter flow. Changes in annual extreme flows and October flows lead to negative ecological implications downstream of the TGD. Ecological considerations should be taken into account during operation of the TGD in order to mitigate the negative effects on the fluvial ecosystem in the middle reach of Yangtze River. The framework proposed here could be a robust method to assess the cumulative impacts of reservoir operation over time.

The Three Gorges region is rich in water resources. With the added impact of impoundment and discharge of the Three Gorges Reservoir, the regional hydrodynamic environment is complex, and research on the impacts of this terrestrial water is still relatively scarce. Using the CORS network supplemented by a small amount of gravity station data, and using the load deformation and gravitational field spherical harmonic analysis method, the crustal deformation and gravity changes caused by the terrestrial water in the Three Gorges area are studied. We find that it is possible to use the CORS network to monitor the crustal deformation and ground-level gravity changes that are caused by the terrestrial water load. The impact of the terrestrial water load is up to the centimeter-level on the vertical deformation, less on the horizontal deformation, and up to hundreds of microgals in the ground level gravity variations. From January 2011 to June 2015, the vertical deformation caused by the terrestrial water load change tends to be balanced, and the influences of gravity changes are mainly concentrated in the Three Gorges Reservoir and the Jianghan Plain. Except for some areas, the crustal vertical deformations caused by the terrestrial water measured by CORS and GRACE are highly consistent in their distribution patterns and trends. In this paper, the research results can be used for monitoring the hydrodynamic environment and for the protection and utilization of water resources, which can also be used to dynamically maintain the elevation and gravity benchmarks.

This study examined the temporal trend of sedimentation in China's Three Gorges Reservoir (TGR) from compiled sediment data at multiple temporal scales. Based on decade-averaged annual sediment loads, a decreasing trend of sediment supply between 1950s and 2000s was found, with a lower-than-expected mean sedimentation rate. From 2003 to 2013, the annual sediment supply generally decreased, with the annual sediment deposition rate being about 50% less than that predicted with prior numerical models. The reduced annual sedimentation rate was attributed to (relatively) small dam building within the upstream watershed, conservation activities and sand/gravel mining. Morphological changes at two cross sections within the TGR between 2003 and 2013 indicated that sediment deposition caused only limited bed accretion along the main course of the TGR. In the tail area of the TGR, where sediment transport ceases first, the sedimentation occurring between 2004 and 2013 was insufficient to impede navigation. These results indicate that at least as a first approximation sedimentation in the TGR is well controlled, making it a subdued ‘river dragon’.

In conventional reservoir operations, energy and economic benefits are typically optimized, and ecosystem values are only addressed as constraints. To reduce the negative influence of reservoir operation on the downstream ecological environment, ecological targets should be incorporated into reservoir operations. The concept of environmental flow was developed to define the quantity, quality and timing of water flows that are required to sustain freshwater and estuarine ecosystems. Based on the salinity requirements of the indicator species and the relationship between salinity and the freshwater inflows, environmental flows for the Yangtze Estuary were determined. Subsequently, an ecological reservoir operation model was established that incorporated the ecological target for the protection of the Qingcaosha water source; the Non-dominated Sorting Genetic Algorithm II was applied to the model. Three typical periods of wet, normal and dry years were selected, and the operation results were analysed for the downstream Datong cross-section and the environmental flows. The results showed that joint scheduling should be performed for the reservoirs upstream of the Yangtze Estuary. In June of wet and normal years, the current run-off of the Datong should be reduced by 13.5% and 5%, respectively. In July and September of wet years, current run-off should be reduced by 30.6% and 25.5%, respectively, as these reductions will not negatively affect the drinking-water sources. The results of this study should provide guidance in decision-making to improve the operation of the Three Gorges Reservoir. Copyright © 2015 John Wiley & Sons, Ltd.

The ecological and environmental consequences of large dam projects have received increasing attention in the recent decades. On the basis of daily water-level data, six periods of TM/ETM+ data and a digital elevation model, the eco-hydrological environments and vegetation area of East Dongting Lake, were compared for the years 1995–2011, spanning periods before and after the implementation of the Three Gorges Dam (TGD) in 2003. Vegetation area (including three types: forestry, reed and grass) continuously expanded, and the minimum elevation of vegetation-covered area (VCA) gradually decreased by 0·88 m from 1995 to 2011. Following the implementation of the TGD, the rates of both vegetation expansion (12·3 vs 14·1 km2 year−1) and the lowering of minimum elevation of VCA (3·1 vs 7·9 cm year−1) increased rapidly. Monthly water level decreased considerably from July to November, and annual submergence duration at elevations of 22–26 and 30 m was considerably decreased after the TGD was implemented. The average maximum submergence duration of VCA was 231 days. Almost equal linear equations describing elevation change from 1995 to 2011 indicated that the minimum elevation of VCA identified via analysis of TM/ETM+ images can be represented by the maximum submergence duration evaluated via daily water level. These data indicate that vegetation colonized the non-vegetation area (including mud beach or water body) more quickly after the implementation of the TGD, due to the drastic changes in eco-hydrological environments such as the decreasing water level and the minimum elevation of VCA. The present methodology might allow faster and more reliable assessment of inundation related landscape impacts on a basin scale and thereby contribute to biodiversity monitoring and policy assessment. Copyright © 2014 John Wiley & Sons, Ltd.

Summary Larval abundance of fish species downstream of large dams generally declines with changes in flow and thermal regime caused by dam operation. Fish conservation strategies in dammed rivers may need to be modified because adjustments in life-history or spawning behaviour are necessary for adult fishes to survive in modified environments. We used genetic programming to identify significant pre- and post-dam environmental factors affecting larval abundance of four major Chinese carp species in the Yangtze River downstream of the Three Gorges Dam and to quantify their relationships with larval abundance during a 13-year period (1997–2009) that encompasses seven pre-dam years and six post-dam years. Significant pre-dam factors included duration and rise rate of flow increase. With a nonlinear correlation, larval abundance slightly increased with duration of flow increase (Duration) when 2 days ≤ Duration ≤ 4 days, but significantly increased with Duration when 5 days ≤ Duration ≤ 8 days. With an approximate linear correlation, larval abundance increased with average daily rise rate of flow increase (QRavg) when QRavg ≤ 2000 m3 s−1 day−1. Timing of flow increase was the most significant post-dam factor, with the majority of adult carp spawning 55–80 days after water temperature at Yichang gauge station reached 15 °C. Duration of flow increase remained significant and its relationship with larval abundance remained unchanged, but rise rate of flow increase was no longer identified as a significant factor. Water temperature became significant with larval abundance decreasing slightly with maximum water temperature of flow increase (WTmax) when 22 °C ≤ WTmax ≤ 26 °C. Changes in the significance of individual environmental factors were caused by adaptation to thermal regime alterations through a gradual delay in spawning time. Because the delayed spawning period was much closer to, or even overlapped with the main flood season, magnitude and rise rate of flow increase and water temperature all increased. These changes, coupled with a lack of long flow increase (Duration ≥ 5 days), the occurrence of dissolved gas super-saturation and the disappearance of most spawning grounds in the Three Gorges Reservoir, resulted in a substantial decline in carp larval abundance of the middle Yangtze River. Variation in the significant factors and their relationships to larval abundance implies that mimicking a natural flow regime without accounting for fish response to environmental changes may not provide the environmental flows needed to enhance native fish spawning. Based on pre- and post-dam relationships between significant factors and larval abundance, we recommend that in order to enhance the four carp species spawning, the Three Gorges Reservoir should plan at least one flow release with increased discharges (Duration ≥ 5 days, 900 ≤ QRavg ≤ 3000 m3 s−1 day−1 and discharge ≤ 30 000 m3 s−1) between 15 June and 20 July when water temperature is

Objectives To investigate the impact of the Three Gorges Dam on the local ecological environment. We conducted a 3-year cross-sectional survey of natural focus infectious diseases in the area before and after the water level rose to 156 m to evaluate the dam's health impacts. Methods Direct and indirect immunofluorescence methods were applied to detect rat antigen and antibody of haemorrhagic fever with renal syndrome (HFRS). Fresh rat kidneys were inoculated in Korth's culture medium to detect Leptospira. A group of captured crabs were ground to observe the metacercariae of Paragonimus. Serum samples were collected from healthy local individuals. ELISA kits were used to detect human antibody against HFRS and paragonimiasis. Human Leptospira infections were detected by a microscopic agglutination test. Results Upstream rodent density increased significantly with Rattus flavipectus and Apodemus agrarius as the major pathophoric genera. The infection rate of human HFRS and Leptospira in the upstream human population samples was significantly higher than in the downstream samples and correlated with the increase in rodent density. Paragonimus infection rates remained at a low level during the study. Culex pipiens fatigan and Armigeres obturbans were the dominant species of mosquito. Conclusions The creation of the Three Gorges Dam changed the proliferation of intermediary agents of diseases, but not notably. However, the ecological effects on the environment may require a prolonged period of time to manifest themselves; thus, long-term and effective surveillance of vectors and related diseases needs to be established. Objectifs Investiguer l'impact du barrage des Trois Gorges sur l'environnement ecologique local. Nous avons mene une enquete transversale de focalisation naturelle de trois ans sur les maladies infectieuses dans la region avant et apres l’elevation du niveau de l'eau a 156 m, afin d’evaluer les impacts du barrage sur la sante. Methodes Des methodes d'immunofluorescence directe et indirecte ont ete appliquees pour detecter l'antigene de rat et les anticorps de la fievre hemorragique a syndrome renal. Des reins de rat frais ont ete inocules dans le milieu de culture de Korth pour detecter Leptospira. Un groupe de crabes captures ont ete broyes pour observer les metacercaires de Paragonimus. Des echantillons de serum ont ete preleves chez des individus locaux sains. Des Kits ELISA ont ete utilises pour detecter les anticorps humains contre la FHRS et la paragonimose. Les infections humaines a Leptospira ont ete detectees au moyen d'un test d'agglutination microscopique. Resultats La densite de rongeurs en amont a augmente de facon significative avec Rattus flavipectus et Apodemus agrarius comme principaux agents intermediaires de maladies. Le taux d'infections FHRS humaines et a Leptospira dans les echantillons de la population humaine en amont etait significativement plus eleves que dans les echantillons en aval, et en correlation avec l'augmentation de la densite des rongeurs. Les taux d'infection a Paragonimus sont restes a un niveau bas durant l’etude. Culex pipiens fatigan et Armigeres obturbans etaient les especes de moustiques dominantes. Conclusions La creation du barrage des Trois Gorges a change la proliferation des agents intermediaires de maladies, mais pas de facon notable. Cependant, les effets ecologiques sur l'environnement peuvent exiger une periode prolongee de temps pour se manifester. Ainsi une surveillance a long terme et efficace des vecteurs et des maladies connexes doit etre etablie. Objetivos Investigar el impacto de la presa de las Tres Gargantas sobre el medio ambiente ecologico local. Para ello, hemos llevado a cabo un estudio croseccional de tres ano sobre los focos naturales de enfermedades infecciosas en el area, antes y despues de que el nivel del agua aumentase 156 m, con el fin de evaluar el impacto de la presa sobre la salud. Metodos Se aplicaron metodos de inmunofluorescencia directa e indirecta para detectar antigeno de rata y anticuerpos de fiebre hemorragica con sindrome renal. Se inocularon rinones frescos de rata en medio de cultivo de Korth para detectar Leptospira. Se buscaron metacercos Paragonimus en un grupo de cangrejos capturados. Se recolectaron muestras de suero de individuos locales sanos. Se utilizaron kits de ELISA para detectar anticuerpos humanos frente a fiebre hemorragica con sindrome renal (FHSR) y paragonimosis. Las infecciones humanas por Leptospira se detectaron mediante una prueba microscopica de aglutinacion. Resultados La densidad de roedores rio arriba aumento de forma significativa, siendo Rattus flavipectus y Apodemus agrarius los generos mas patogenicos. La tasa de infeccion humana con FHSR y leptospira en las muestras de la poblacion rio arriba era significativamente mayor que en las muestras rio abajo, y estaban correlacionadas con un aumento en la densidad de roedores. Las tasas de infeccion por Paragonimus continuaban siendo bajas durante el estudio. Culex pipiens fatigan y Armigeres obturbans eran las especies dominantes de mosquito. Conclusiones La construccion de la presa de las Tres Gargantas cambio la proliferacion de los agentes intermediarios de la enfermedad, pero no de manera notable. Sin embargo, los efectos ecologicos sobre el medio ambiente podrian requerir de un periodo de tiempo prolongado antes de manifestarse, por lo que seria necesario establecer una vigilancia efectiva y a largo plazo de los vectores y de las enfermedades relacionadas.

Extremely low water level events have frequently occurred in the middle–lower Yangtze River (MLYR) in recent years (2006–2011). Most of these drought events coincided with the initial operation of the Three Gorges Dam (TGD). The TGD was therefore the focus of controversy about the causes of the hydrological droughts of the rivers and lakes of the region. We quantified the effects of the TGD's operation on water levels from 2006 to 2011 using a newly developed hydrodynamic model. The operation of the TGD significantly exacerbated the severe hydrological droughts that occurred in late September to November because of water impoundment, but it increased water levels from April to early June in the MLYR because of the drawdown of TGD water levels. Evidence suggests that the recent extremely low water levels were mainly because of the remarkable decline in inflows to the MLYR resulting from precipitation changes and possible human activities. Nevertheless, it should be noted that the effects of the TGD on downstream rivers and lakes will be intensified in the foreseeable future. Copyright © 2013 John Wiley & Sons, Ltd.

Large dams often alter flow and thermal regimes downstream, resulting in fish spawning delays and larval abundance declines. Accurate prediction of the delayed spawning period under changed thermal regime is critical for selecting a correct timing to modify dam operation and to release the environmental flow needed to enhance fish spawning. We used correlation analysis to investigate the relationship between thermal regime alteration and spawning delay of the four major Chinese carps (FMCC) below the Three Gorges Dam in the Yangtze River, China, using a 13-year ecological data series (1997–2009). Eighteen variables were defined to quantify thermal regime and related to two variables representing spawning timing. Our results demonstrate that the start of FMCC spawning has been delayed from early May to middle June since the Three Gorges Dam initiated operation in 2003. Water temperature declines of 2 °C–4 °C in March, April and May (a critical period for gonad development) were the principal reason for the observed spawning delay. The variable most associated with spawning timing was the arrival date of the cumulative temperature needed for gonad development from stages IV to V (DDegDayIV–V), which describes the long-term impacts of the timing, magnitude and duration of thermal regime upon gonad development. Only the cumulative temperature for gonad development and the minimum temperature for FMCC spawning (18 °C) are both satisfied, the occurrence of suitable flow conditions, that is, flow increase or flash flood, would produce a successful spawning event. Consequently, we suggest that the experimental flow increase process of the Three Gorges Reservoir aimed at enhancing FMCC spawning should initiate after 15 June when the requisite thermal regime can be met. Copyright © 2013 John Wiley & Sons, Ltd.

The water body is just like a quasi-static fluid after the impoundment of the Three Gorges Reservoir in China to 175 m water level in late 2010. In this paper, fluid dynamic model and numerical method were presented to analyse its dynamic characteristic. Then, based on an oil spill model coupled with the hydrodynamic model, the oil fractions evolvement with time as well as the recovery process with emergency actions under oil spills were numerically simulated and illustrated in the Three Gorges Reservoir. Emergency actions were accordingly analysed based on the simulated pollution area and density, by which a decay parameter was additionally brought into the simulation to understand the recovery of polluted area. The simulated results could be an aid for better emergency response strategy in case of oil spill accidents in the Three Gorges Reservoir in China.

Since the Three Gorges Reservoir (TGR) was put into operation in June 2003, the effects of the TGR on downstream hydrology and water resources have become the focus of public attention. This article examines the effects of the TGR on the hydrological droughts at the downstream Yichang hydrological station during 2003–2011. The two-parameter monthly water balance model was used to generate the monthly discharges at the Yichang station for the period of 2003–2011 to represent the unregulated flow regime and thus to provide a comparison benchmark for the observed flow series at the Yichang station after the operation of the TGR. To provide a reference series for the observed monthly discharge series of the entire study period of 1951–2011, we constructed the naturalized monthly discharge series at the Yichang station by joining the observed monthly discharge at the Yichang station for the period of 1951–2002 and the two-parameter monthly water balance simulated monthly runoff at the Yichang station for the period of 2003–2011. For both the observed and naturalized monthly discharge series of 1951–2011, the hydrological drought index series were calculated using the standardized streamflow index method. By comparing the drought indices of these two monthly discharge series, we investigated the effects of the TGR on the hydrological droughts at the downstream Yichang station during 2003–2011. The results show that the hydrological droughts at the downstream Yichang station are slightly aggravated by the TGR's initial operation from 2003 to 2011. The river flow reduction at the Yichang station after impoundment of the TGR might account for the downstream drought aggravation. Copyright © 2012 John Wiley & Sons, Ltd.

The effects of body mass (M) and temperature (T) on routine metabolic rate (m(R) ) were assessed in the largemouth bronze gudgeon Coreius guichenoti, from Three Gorges Reservoir, Yangtze River, China. The m(R) increased with increasing M by factors (b-value in the equation m(R) = aM(b) ) of 0·843, 0·800, 0·767, 0·788 and 0·822 at 10, 15, 20, 25 and 30° C, respectively. A significant interaction between M and T on m(R) was observed. The variation in the b-value at different T suggests that the b-values were not consistent with the universal allometric exponent 0·75. After controlling for M, the relationship between the normalized standard metabolic rate (m(S), mg O(2) kg(-1) h(-1)) and T was described by an exponential equation: m(S) = 9·89e((0·093T)) . The results indicate that the effects of M on m(R) depend on T. The increased water temperature induced by dam construction on the Yangtze River may cause a marked increase in energy demand by this species, with potential ecological consequences.

Hydrodynamic flow fields affect the ecological processes such as the water diversity and the distribution of organisms. Understanding the hydrodynamic and ecological processes is critical for the restoration and protection of especially fragile ecological habitats in river systems. This study uses turbulent flow to characterize the ecological behaviour of Chinese Sturgeon (Acipenser sinensis) in the Yangtze River. The Delft3D-Flow model, which is first validated with field-measured data, is used to simulate the flow field within spawning habitats of Chinese Sturgeon, downstream of Gezhouba Dam. The model-simulated turbulent kinetic energy (TKE) and its distribution pattern are then used to characterize the hydraulic environment of the fish's spawning habitat. For the spawning habitat, downstream of Gezhouba Dam, the lower limit of TKE for the Chinese Sturgeon egg mass field is 0.025 m2/s2, which occurs at a velocity less than 1.7 m/s. Chinese Sturgeon prefers habitats with TKE range of 0.010 ~ 0.015 m2/s2 for resting. This suggests that discharge regimes provide the basis for ecological regulation of the Three Gorges Reservoir and the scientific reference for river management. Copyright © 2011 John Wiley & Sons, Ltd.

The paper introduces the anomalies observed by digital tiltmeter, cross-fault deformation meter, 4-component borehole strainmeter and geothermometer before May 12, 2008, Ms8.0 Wenchuan earthquake, Sichuan. The digital tiltmeter installed in the epicentral region in Shifang County recorded the tilt anomalies 15 days before the earthquake with variation amplitude of 3.7 times larger than the annual deviation of 2007. The cross-fault deformation meter installed at Zimakua station on the Xianshuihe-Anninghe fault zone detected displacement anomaly occurring since 2006 with the variation amplitude exceeding the cumulative value of the last ten years. Five borehole strainmeter stations in the Chongqing section of Three Gorges Reservoir area observed unconventional strain changes occurring in the period from May 1 through 12, 2008. Among them, the strainmeter at Wanzhou station recorded the great compression strain rate on the EW component at 14:00 o'clock of May 10, and the anomaly amplitude was so large that the instrument output exceeded its dynamic range, corresponding to a level of ∼104 nanostrains. The geothermometers installed in Xi'an, Chongqing and Xichang recorded the sudden temperature changes from November 2007 to January 2008 with the variation amplitudes several times larger than the ordinary deviation. The above phenomena and the criteria for distinguishing the anomalies from background fluctuations are discussed in this paper.

The vertical ship lift at the Three Gorges Dam in China will consist of a reinforced concrete structure with an internal steel ship chamber. The chamber will be a self-supporting orthotropic plate structure, continuously suspended from ropes with counterweights. Its components, such as segment gates, drive, horizontal guiding systems in the longitudinal and transverse directions plus locking and safety mechanisms are described here. A special procedure for reducing the tolerances of the steel components embedded in the reinforced concrete structure is explained.

Excavations at a salt-production site named Zhongba in the Three Gorges region of China document a complex system of intersecting activities that changed gradually over a long period of time. As the salt production became much larger in scale during the Bronze Age, the context of this production shifted from one for which there is no archaeological evidence for attachment between producers and those who control the products to a situation in which the exchange of salt to other regions seems to have been controlled, or at least directed, by an emergent elite whose authority was based in part on divinatory ability and the control of ritual knowledge. This study examines the concept of context in relation to the organization of salt production at this site and argues that multiple lines of evidence must be considered if we are to avoid simplified assumptions concerning the nature of products and the production processes through which they are made.

Zur Beforderung von Passagierschiffen am Drei-Schluchten-Staudamm am Yangtze ist in der Nahe der Stadt Yichang ein Senkrecht-Schiffshebewerk nach dem Gegengewichtsprinzip vorgesehen, das derzeit durch die China Yangtze Three Gorges Project Corporation, Bauherr und Betreiber des Drei-Schluchten-Staudamms, geplant wird. Mit der Ausschreibungsplanung ist die “German Design Group”, ein deutsches Joint Venture, bestehend aus Krebs und Kiefer International und Lahmeyer International, beauftragt. Berater des Bauherrn im Sinne eines “Panel of Experts” ist die Bundesanstalt fur Wasserbau. Design of the ship lift at the Three Gorges Dam in China. A vertical ship lift based on the counterweight principle is to be built to allow passenger ships passing the Three Gorges Dam at the Yangtze River near Yichang. This project is realized by the China Yangtze Three Gorges Project Corporation, building and operating company of the Three Gorges Dam. The German joint venture, “German Design Group”, incorporating the two companies Krebs und Kiefer International and Lahmeyer International has been entrusted with the general layout, intermediate and final design. As part of the “Panel of Experts” the German Bundesanstalt fur Wasserbau (Federal Waterways Engineering and Research Institute) provides consulting support to the building company.

This contribution looks at the Three Gorges dam project, and specifically at the resettlement programme, focusing on two major aspects. It examines the resettlement programme in relation to the environmental capacity in the reservoir area; and it assesses the existence of a risk consciousness and a reconstruction strategy, seen in terms of the ‘impoverishment risks and reconstruction’ (IRR) model. The author argues that issues related to the environment and natural resources are highly significant and have led to changes in the resettlement programme, including a change in policy towards moving rural people out of the reservoir area, as well as the issuing of new resettlement regulations. The IRR model is a useful tool to identify risks and can serve as a guide to the reconstruction of livelihoods for the resettled people. The limitations of using the model in the Three Gorges project concern specific Chinese environmental, social, economic and political conditions that influence efficient resettlement implementation. The Chinese authorities’ emphasis in resettlement has been on rebuilding relocatees’ livelihoods: it focuses less — if at all — on the social aspects and the social trauma of broken networks. The IRR model could therefore be useful in the context of focusing more on the social costs of resettlement.

The Three Gorges Dam on the Yangtze River is currently the largest construction project in the world. Because of its complexity, integration of social, environmental and technological systems, and tight coupling required by the schedule, the project should be managed using a systems approach. To find out if this was the case, the authors formed a research team, sponsored by the International Society of Systems Sciences, to tour the dam sight, interview managers and engineers, travel up the Yangtze to Chongqing, analyze problems posed by the critics of the dam and, finally, report back to the ISSS annual meeting in Shanghai following the trip. This paper reports on the team's observations, the results of the interviews and a systems model that analyzes the problems facing the dam builders. Finally, the paper concludes that the engineers and managers are aware of the interrelated problems and have planned for their solution. Copyright © 2004 John Wiley & Sons, Ltd.