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The article examines the relationship between China’s exports to African countries and the implementation of energy projects by Chinese companies. The structure of Chinese exports to Africa and trends in the development of bilateral trade is analyzed. Key factors explaining the close correlation between exports and project implementation are: first, the significant volume of tied financing provided by Chinese banks for the construction of energy infrastructure in African countries, second, the need of these countries to purchase a lot of high-tech equipment in the absence of relevant industries on their territory. The dynamics of supplies of specialized equipment from China used for the construction of various types of power plants - hydroelectric power plants, thermal power plants, wind power plants and solar power plants - is considered in detail. The article provides examples of energy projects of Chinese companies in African countries, for which the supply of equipment is directly found in the imports of the respective countries from China. The tendency for Chinese companies to open production facilities in African countries, in particular cement plants and a photovoltaic modules plant, is noted. The author concludes that the African market remains extremely promising for the implementation of energy projects and the sale of relevant Chinese products despite some negative factors.

Climate change and human activities have an important impact on the changing environment, leading to significant changes in the basin water cycle process. The Jialing River Basin, the largest tributary of the upper Yangtze River, is selected as the study area. Three different rainfall datasets, the China Meteorological Assimilation Driving (CMAD) dataset, the Tropical Rainfall Measuring Mission data, and gauged observation data, were used as inputs for the MIKE System Hydrological European (MIKE SHE) model. By comparing the simulation results driven by various meteorological data, the applicability of the MIKE SHE model at four stations is evaluated, and the sensitivity and uncertainty of model parameters are analyzed. Meanwhile, the impact of large hydropower stations on the runoff of the Jialing River Basin is assessed, and the influence of human activities on the runoff change is determined. The future climate change of the watershed was analyzed by using the typical representative concentration pathway (RCP) 4.5 and RCP8.5 climate scenarios. Based on the MIKE SHE model, the runoff of the Jialing River Basin in the future climate scenario is predicted, and the corresponding response of the Jialing River Basin is analyzed quantitatively. The results show that the CMAD data-driven model has better Nash–Sutcliffe efficiency and correlation coefficient for each period. By analyzing the influence of the hydropower station on the runoff process at the outlet of the basin, it is found that the hydropower station has a certain regulating effect on the runoff process at the outlet of the basin. In addition, the RCP4.5 scenario is more consistent with the future scenario, indicating that the Jialing River Basin will become colder and drier. HIGHLIGHTS By comparing the results of the MIKE SHE model driven by the China Meteorological Assimilation Driving dataset, the Tropical Rainfall Measuring Mission data, and gauged data, the applicability of model parameters of the MIKE SHE model is evaluated, and the sensitivity and uncertainty of model parameters are analyzed.; The impact of large hydropower stations on the runoff of the Jialing River Basin is assessed, and the influence of human activities on the runoff change is determined.; Runoff prediction was conducted under two future climate scenarios, and the response of runoff to future climate changes was quantitatively analyzed.

The cofferdam built at the inlet of the diversion tunnel may be left due to incomplete blasting demolition, which affects the river closure. Several indexes have been used to evaluate the difficulty of river closure, but all indexes suffer from their limitations in use. Thus, it is more useful to combination multiple indexes to analyze the impact of residual cofferdam. Taking the river closure project of a Hydropower Station in southwest China as an example, the influence of the residual cofferdam heights on the river closure was studied by experiments. The discharge of river closure is 590 m3/s and 758 m3/s. In this paper, the results of studies on a 1:50 scale hydraulic model based on the Froude similitude relationships are presented. The test results show that the discharge capacity of the diversion tunnel is reduced by 27.2% at most when this height is more than 2 m. The residual height mainly affects the maximum of stream energy with unit width, which increase by more than 50% at most compare to Non-existent residual cofferdam. However, the final drop, max-velocity along the gap axis, the local scour of riverbed and the flow pattern of the gap are basically not affected. In addition, with the height increase, the bank collapse is intensified, and the amount of dumped material with medium size increases, especially when it reaches 4 m, the large or Extra-large size stones begin to be dumped. Based on the comprehensive evaluation of multiple indexes and the type of dumped material, it is shown that the residual cofferdam height more than a certain value, the value is 2 m for the case study, will significantly increase the river closure difficult.

Hydropower is a kind of clean energy, which can effectively reduce the consumption of fossil energy and is one of the main fields of new energy development. Pumped storage power station not only provides a solution for storing electric energy and generating excess, but also is a clean, efficient, economical and safe power system regulation method with high quality. Accurate modeling of a pump-turbine, as the core equipment of a pumped storage unit, is the key to safe and stable operation of the pumped storage unit. At present, a method of simplifying the external characteristics of a pump-turbine into a first-order linear model is widely used, which cannot effectively and accurately reveal the nonlinear dynamic characteristics of the unit in transition process. In order to meet the demand of high-precision simulation of the unit, a new method of identifying Taylor series expansion considering nonlinearity based on the torque characteristic formula and the flow characteristic formula is proposed, which is applied to the pump-turbine external characteristic model, and retains the second derivative term, making the model a second-order nonlinear model, and thus, the pump-turbine model becomes a nonlinear model. The nonlinear model established is used to simulate the load increase and load rejection of the unit, and the results are compared with those for the linear model. The comparison shows that the nonlinear model established for the pump-turbine can reveal the dynamic response of the unit more effectively and accurately than the linear model, and provide a further guarantee for the safe and stable operation of pumped-storage units, which is of great significance to hydropower energy development.

The green peafowl (Pavo muticus) is one of the most threatened pheasants in the world. In China, it is widely appreciated for its beauty as well as historical and cultural value, but current populations number less than 500 individuals. Recently, Tang and colleagues reported in Science that the green peafowl is likely to become extinct due to the construction of the Jiasajiang Level 1 Hydropower Station within the Red River Upstream District (RRUD) and thus called for a stop to this project (Tang et al., 2019). According to our recent surveys, however, this species is still extant in 22 counties of Yunnan Province, China, among which, only two within the RRUD have been predicted to be affected by floods from the hydropower station. Therefore, the conclusion that the species will likely go extinct in China upon completion of the dam is unwarranted. In fact, construction of the Jiasajiang Level 1 Hydropower Station was stopped in August 2017. The main challenge for green peafowl conservation is that over 65% of the population occurs outside of protected reserves in China. Fortunately, the Chinese government has adopted an Ecological Redline (ERL) strategy to achieve ecological civilization plans, thus bringing new hope to the conservation of green peafowls both inside and outside of protected reserves. As a top conservation priority for China, the government is fully committed to conserving this peafowl.

The critical stable sectional area (CSSA) for surge tanks corresponds to the critical stable state of hydropower stations and is an important index to evaluate the stability of the turbine regulation system. The research on CSSA for surge tanks is always one of the most important topics in the area of transient processes of hydropower stations. The CSSA for surge tanks provides the value basis for the sectional area of surge tanks. In engineering practice, the CSSA for surge tanks is widely used to guide their hydraulic design. This paper provides a systematic literature review about the CSSA for surge tank of hydropower stations. Firstly, the CSSA for surge tanks based on hydraulic transients is discussed. Secondly, the CSSA for surge tanks based on hydraulic-mechanical-electrical coupling transients is presented. Thirdly, the CSSA for air cushion surge tanks is illustrated. Finally, the CSSA for combined surge tanks, i.e., upstream and downstream double surge tanks and upstream series double surge tanks, is presented. In future research, the CSSA for surge tanks of pumped storage power stations should be explored. The CSSA for surge tanks considering multi-energy complement is worth studying.

Unsteady flow induced by hydropower stations exerts a significant impact on the water level in multi-approach channels, which directly threatens the safe passage of ships. In this study, a one-dimensional and a two-dimensional hydrodynamic model are adopted to simulate the water level fluctuations at the entrance of multi-approach channels and the lower lock head of a ship lift with consideration of initial water surface elevation, base flow, flow amplitude, regulation time, and locations of hydropower stations, unfavorable conditions are successfully identified, and the fluctuations at the approach channel entrance and the lower lock head of a ship lift under single-peak and double-peak regulating mode are analyzed considering the flow regulating of the Gezhouba Hydropower Station (GHS), thus, the water level oscillation process in the multi-approach channels is presented. Results show that the largest wave amplitude in the multi-approach channels manifests under unfavorable conditions including lower initial water surface elevation, smaller base flow, larger flow variation, and shorter regulation time, and water level fluctuation in the multi-approach channel is primarily induced by flow amplitude and net flow between the Three Gorges Hydropower Station (TGHS) and the GHS, with consideration of the counter-regulation process of the GHS. This research contributes to providing a reference for a similar large-scale cascade hydropower station regarding regulation and control of navigation conditions.

Construction of hydropower stations has been an important approach to meet China’s increasing power demand, but the impact of construction of hydropower stations on river microbiota is not fully understood. To evaluate this, the microbial composition from 18 sampling sites in the downstream of Jinsha River of China, upstream and downstream of two completed and two under-construction hydropower stations, were analyzed using high-throughput 16S rRNA gene sequencing. Three independent samples from each site were analyzed. A total of 18,683 OTUs from 1,350 genera were identified at 97% sequence similarity. Our results showed that the completion of hydropower stations would significantly increase the relative abundances of Acidobacteria, Chlorobi, Chloroflexi, Cyanobacteria, Nitrospirae, and Planctomycetes, especially the relative abundance of Synechococcus dOTUs and thus increase the risk of algal blooms. PCA based on all KEGG pathways and the significantly different KEGG pathways showed the predicted metabolic characteristics of the water microbiota by PICRUSt in the activated hydropower station group were significant difference to the other groups. Results from canonical correspondence analysis showed that water temperature and dissolved oxygen had significant effects on microbiota composition. These results are important for assessing the impact of hydropower stations on river microbiota and their potential environmental risks.

The feasibility of flow pattern in pressure forebay of hydropower station is studied by using computational fluid dynamics method (CFD). First, calculation is verified through typical examples based on Flow-3D of CFD software, and the good agreement between calculating results and empirical formula shows the accuracy and reliability of CFD method. Then, taking a specific hydropower station for an example, velocity distribution and the flow pattern variation of pressure forebay under three different operating conditions such as full load rejection, one-unit load acceptance and two-unit successive load acceptance are analyzed in details. The study shows that, at full load rejection and load acceptance conditions, the flow pattern at water inlet is good and water level fluctuation is steady although vortex shapes in a pressure forebay. It provides a basis for the hydraulic optimization design of pressure forebay.

The global energy shortage has revived the interest in hydroelectric power, but extreme geological condition always pose challenges to the construction of hydroelectric power stations with large underground caverns. To solve the problem of safe design of large underground caverns, a Chinese-style intelligent stability design, representing recent developments in Chinese techniques for the construction of underground hydropower systems is presented. The basic aim of this method is to help designers improve the stability and design efficiency of large underground hydropower cavern groups. Its flowchart consists of two parts, one is initial design with an ordinal structure, and the other is dynamic design with a closed loop structure. In each part of the flowchart, analysis techniques, analysis content and design parameters for caverns’ stability are defined, respectively. Thus, the method provides designers with a bridge from the basic information of objective engineering to reasonable design parameters for managing the stability of hydraulic cavern groups. Application to two large underground caverns shows that it is a scientific and economical method for safely constructing underground hydraulic caverns.

The emission of Greenhouse gases (GHG) during the life cycle of four hydropower stations with installed capacity from 95 MW to 500 MW are assessed by the integrated GHG reservoir tool developed by International Hydropower Association. Model inputs are extracted from multi-source geographic datasets and construction planning documents. Three main conclusions are summarized: (1) In pre- and post-impoundment stages, areal GHG emission balance in reservoir area depends on the climate background, humid subtropical regions are more active than arid temperate regions. In the construction stage, emissions from fill, concrete and equipment account for more than 70% of the total. (2) GHG intensity falls rapidly when lifetime increases from 10 to 40 years and then drops slightly when lifetime becomes longer, which is 13.60 tCO2e/GWh for 50 years and 8.13 tCO2e/GWh for 100 years on average. The emission rates of hydropower stations with lower installed capacity are obviously large if they work for less than 30 years and differ less with stations possessing a higher installed capacity when their lifetime approaches 100 years. (3) Comparing with electricity generated by coal in China whose GHG intensity is 822 tCO2e/GWh, hydroelectricity is almost 100 times more efficient and clean. Thus, hydropower station plays an important role in dealing with the global warming issue as a substitution for a fossil fuel power source.

Smolt og vinterstøing produsert ovenfor Rygene kraftverk, må passere kraftverket under nedvandring. Fisken kan passere kraftverket med bruk av turbinløpet. Bruk av turbinløpet vil medføre at i størrelsesorden 15 til 50 % av all smolt og nær all vinterstøing < 80 cm vil avlives. All fisk større enn dette vil dø fordi de ikke kan passere varegrinda plassert foran turbininntaket. Våren 2013 ble det gjort forsøk med tiltak: Isløpet, som er plassert vinkelrett på varegrinda, ble da åpnet. For å måle effektiviteten av tiltaket ble smolt merket med passive integrerte transpondere (PIT-merker) og satt ut oppstrøms kraftverket. Av disse ble ca. 40 % gjenfanget i isløpet. Samtidig benyttet 170 vinterstøing og mye sørv isløpet. Tiltaket var ikke optimalt, men fungerte bedre enn forventet. For å oppnå større bruk av isløpet, må det gjøres ytterligere tiltak. Dette kan innebære ombygging av varegrinda, alternativt etablering av ledegjerder. Samlet utvandret det 2399 smolt forbi Rygene i 2013. For elva mellom Rygene og Fuglefjell ble bestanden estimert til 952 smolt. Til sammen utvandret det dermed ca. 3400 smolt fra Nidelva. Dette var langt færre enn forventet basert på ulike produksjonsestimat. Estimat basert på tilgjengelig habitat, antall gytefisk og gytebestandsmål antyder at det skulle utvandre noen 10-tals tusen smolt. Årsaken til dette misforholdet må skyldes forhold oppstrøms Rygene. Det kan være mangel på produksjonsområder og/eller høyt tap av fisk pga. gjeddepredasjon. >Mindre sannsynlige årsaker er mangel på gytefisk, ugunstig vannkjemi eller vannføring. Agder Energi Vannkraft

Bergenshalvøens kommunale kraftverk, BKK, skal bygge ut kraftverket i Matre. Masfjorden kommune ønskjer å nytte utsprengd steinmasse frå tunelldriving til å legge ei 250 m lang fylling frå fastlandet (Storematre) ut til Matresøyna i Matrevågen. Rapporten omhandlar vurderingar knytt til mogleg endring i sirkulasjon og isdanning som følgje av fyllinga og partikkelspreing i samband med utfyllingsarbeidet. Modellberekningar viser ein tydeleg reduksjon i sirkulasjonen i vatnet på nordsida av Matresøyna p.g.a. fyllinga. Dette vil teoretisk også kunne medføre auka isdanning der, men det er konkludert med at fjorden framleis vil forbli isfri om vintrane p.g.a. kraftverksutsleppet. Risikoen for at partiklar frå utfyllingsarbeidet skal nå ut og ned til Havbruksstasjonens sjøvassinntak på 90 m djup vert vurdert som liten. COWI AS