Hydropower Exploitation Research Articles

Exploiting the “white coal” of the Pasvik River. Negotiating corporate and national interests in the border region during the German occupation of Norway

ABSTRACT The history of the Pasvik River, demarcating Norway’s border with Russia in the north is inextricably linked with issues of security and national interests on the one side, and exploitation of natural resources and business interests on the other. This applies not least to the war years, as German warfare in Europe increased the value of the hydropower and the strategic metals of the border region. Drawing on sources from the archives of the mining company AS Sydvaranger and Norwegian state administration, this article traces the negotiations on hydropower exploitation in the Pasvik River throughout the Second World War focusing on Norwegian key actors, and analyses Norwegian national and corporative interests and strategies in the border area during the German dominance in the region.

The interaction between bucket number and performance of a Pelton turbine

The Pelton turbine is a type of hydraulic turbine suitable for medium, high and ultra-high head hydropower exploitation. As energy conversion units, the Pelton turbine has numerous design parameters affecting its energy conversion efficiency. In this paper, a three-dimensional unsteady simulation was conducted to analyze the influence of bucket number on the hydraulic performance and internal flow behavior of a model Pelton turbine. Five different bucket numbers in a total runner were selected for numerical examination, including the optimal number of 21 determined by the empirical formula. As the bucket number increased with the same operating conditions, the predicted hydraulic efficiency of the Pelton turbine rose to the maximum under optimal bucket number and then decline. Compared with the optimal bucket number of 21, the hydraulic efficiency of the Pelton turbine with 15, 17 buckets decreased by 2.8 % and 1 % respectively. By analyzing the variation of torque coefficient and water sheet flow under different bucket numbers, the interacting mechanism between bucket number and performance of the Pelton turbine was discussed. Numerical result indicated that the phase difference of the single bucket torque coefficient affected by the flow pattern exerted an influence on mean of the runner torque coefficient and hydraulic efficiency. This paper provides an in-depth understanding of the bucket number to the flow mechanism in the bucket for exploring the energy conversion efficiency of the Pelton turbine.

Threatened Species of Amphibians and Reptiles from Son La Province and Their Conservation Values

From the field survey research between 2012 and 2021, we herein provide a list of 39 threatened species of amphibians and reptiles from Son La Province. Of these, the following species have high conservation values: two species are listed in the Governmental Decree No. 64/2019/ND-CP, 12 species are listed in the Governmental Decree No. 84/2021/ND-CP, 12 species are listed in the CITES Appendices, 22 species are listed in the Vietnam Red Data Book (2007), and 24 species are listed in the IUCN Red List (2022). In addition, 21 species are being exploited for food and wildlife trade by local people. Major threats to the habitat and populations of amphibians and reptiles in the study areas include deforestation, slash-and-burn cultivation, hunting activities, exploitation of forest products, quarrying, hydropower and road construction, as well as overharvesting for food and trade. The research results provide a scientific base for conservation and management of amphibians, reptiles and biodiversity of Son La Province.
 

A Compact IIoT System for Remote Monitoring and Control of a Micro Hydropower Plant.

Remote monitoring and operation evaluation applications for industrial environments are modern and easy means of exploiting the provided resources of specific systems. Targeted micro hydropower plant functionalities (such as tracking and adjusting the values of functional parameters, real-time fault and cause signalizing, condition monitoring assurance, and assessments of the need for maintenance activities) require the design of reliable and efficient devices or systems. The present work describes the design and implementation procedure of an Industrial Internet of Things (IIoT) system configured for a basic micro hydropower plant architecture and assuring simple means of customization for plant differences in structure and operation. The designed system features a set of commonly used functions specific to micro hydropower exploitation, providing maximum performance and efficiency.

Numerical design methodology for reversible Deriaz turbine with high energy performance and reduced fish impacts

The increased interest for further exploitation of hydropower and pumped hydro storage sites of lower head and capacity, and the tightening on the other hand of the environmental terms and restrictions, would require the design of corresponding hydro turbines and reversible machines with improved environmental performance. This work presents a numerical methodology to optimize the design of a Deriaz turbine in order to achieve high energy efficiency and improved fish friendly behaviour in both pump and turbine operation modes. Various numerical simulation and optimization software and tools are used, while the geometry of the machine is fully parameterized to allow for wide design modifications and corresponding numerical tests. At first, the most important design parameters and their variation range limits are identified by a sensitivity study. Next, several multi-objective optimization procedures are carried out, using general quantitative targets for a comparative evaluation of the various machine runner designs. The results show a complex interdependence or competitiveness of the machine efficiency and the various fish impact performance indices that requires careful analysis. The developed and applied methodology can produce one or more candidate designs that satisfactorily meet all the desired objectives.

Improved hydropower utilization design of the entire Wuding river in Yulin, Shaanxi

Below Cuijiawan, the main stream of Wuding River is basically a canyon section with exposed bedrock in the channel, intermittent plunging rapids, steep riverbed ratio and steep rock walls on both sides, which has favorable conditions for the construction of hydropower projects and is a key section for hydropower exploitation. Through research and analysis of the current water energy development and utilization, this paper combines the comprehensive improvement planning objectives and design ideas to propose a water energy utilization design that is consistent with the actual situation of Wuding River and reasonably budgeted, so that the abundant water energy resources of Wuding River can be fully utilized and the social, economic and ecological benefits can be unified.

Practices of environmental protection, technological innovation, economic promotion and social equity in hydropower development: a case study of cascade hydropower exploitation in China’s Dadu River basin

Practices of environmental protection, technological innovation, economic promotion and social equity in hydropower development: a case study of cascade hydropower exploitation in China’s Dadu River basin

Refined numerical simulation of a concrete cut-off wall in the thick overburden of dam foundation

It is inevitable for dam construction in hydropower exploitation to face a thick overburden foundation with high permeability. The performance of the concrete cut-off wall in an overburden foundation is the key factor to determine dam safety. However, it is difficult to conduct detailed and in-depth study on the wall under complex conditions based on traditional simulation and analysis methods. In this research, the numerical simulation of a concrete cut-off wall in thick overburden are intensively studied. The deformation, stress, and damage distribution of the concrete cut-off wall are analyzed in detail. The importance and necessity of the refined numerical simulation and analysis of a concrete cut-off wall are discussed based on the aspects of scale, grid, analysis content, and method. The results indicate that it is very necessary to conduct a three-dimensional numerical analysis of the cut-off wall. A rough numerical model can be adopted to model the cut-off wall when only deformation is concerned. However, it is necessary to carefully mesh the wall when the stress state is the key research content, and it is more economical and reliable to model the wall with a nonconforming element. Moreover, the plastic damage analysis has revealed that the wall is more liable to tensile damage and the results can be used to establish a direct connection with the anti-seepage performance. In addition, some reinforcement measures have been suggested with a detailed study of the stress generation mechanism and stress direction development process in the concrete cut-off wall. This study can provide a method basis and technical support for the safety design and evaluation of a concrete cut-off wall in the thick overburden of dam foundation.

A century of genetic homogenization in Baltic salmon-evidence from archival DNA.

Intra-species genetic homogenization arising from anthropogenic impacts is a major threat to biodiversity. However, few taxa have sufficient historical material to systematically quantify long-term genetic changes. Using archival DNA collected over approximately 100 years, we assessed spatio-temporal genetic change in Atlantic salmon populations across the Baltic Sea, an area heavily impacted by hydropower exploitation and associated with large-scale mitigation stocking. Analysis was carried out by screening 82 SNPs in 1680 individuals from 13 Swedish rivers. We found an overall decrease in genetic divergence and diminished isolation by distance among populations, strongly indicating genetic homogenization over the past century. We further observed an increase in genetic diversity within populations consistent with increased gene flow. The temporal genetic change was lower in larger wild populations than in smaller wild and hatchery-reared ones, indicating that larger populations have been able to support a high number of native spawners in relation to immigrants. Our results demonstrate that stocking practices of salmon in the Baltic Sea have led to the homogenization of populations over the last century, potentially compromising their ability to adapt to environmental change. Stocking of reared fish is common worldwide, and our study is a cautionary example of the potentially long-term negative effects of such activities.

Impact of Prospective Climate Change Scenarios upon Hydropower Potential of Ethiopia in GERD and GIBE Dams

Ethiopia is growing fast, and the country has a dire need of energy. To avoid environmental damages, however, Ethiopia is looking for green energy polices, including hydropower exploitation, with large water availability (i.e., the Blue Nile, the greatest tributary of Nile river). Besides other dams on the Omo river, the GIBE family, Ethiopia is now building the largest hydropower plant of Africa, the GERD (Grand Ethiopian Renaissance Dam), on the Blue Nile river, leading to tensions between Ethiopia, and Egypt, due to potentially conflictive water management. In addition, present and prospective climate change may affect reservoirs’ operation, and this thereby is relevant for downstream water users, population, and environment. Here, we evaluated water management for the GERD, and GIBE III dams, under present, and future hydrological conditions until 2100. We used two models, namely, Poli-Hydro and Poli-Power, to describe (i) hydrological budget, and flow routing and (ii) optimal/maximum hydropower production from the two dams, under unconstrained (i.e., no release downstream besides MIF) and constrained (i.e., with fair release downstream) simulation. We then used climate change scenarios from the reports CMIP5/6 of the Intergovernmental Panel on Climate Change (IPCC) until 2100, to assess future hydropower production. Our results demonstrate that the filling phase of the GERD, particularly critical, have optimal filling time of 5 years or so. Stream flows at GERD could be greater than the present ones (control run CR) at half century (2050–2059), but there could be large decrease at the end of century (2090–2099). Energy production at half century may increase, and then decrease until the end of century. In GIBE III discharges would increase both at half century, and at the end of century, and so would energy production. Constrained, and unconstrained simulation provide in practice similar results, suggesting potential for shared water management in both plants.

Integrating hydrological, landscape ecological, and economic assessment during hydropower exploitation in the upper Yangtze River

Comprehensive investigation of hydrological processes associated with landscape ecology and economic development plays a key role in watershed management, and is less developed in watersheds with large-scale cascade dams. With the abundant hydropower resources and its unprecedented advantages, hydropower exploitation in the upper Yangtze River (Jinsha River) is critical to energy structure adjustment in China. Therefore, we integrated hydrological modeling, landscape ecology analysis, and economic analysis in the dammed Jinsha River. With climate variations in the Jinsha River Basin, the average flow near the uppermost dams in the mainstream grew from 796 m3 s−1 (1990s), to 918 m3 s−1 (2000s), and further to 1025 m3 s−1 (2010s). During 1991 to 2017, the source power in the headwater region grew slightly, but varied little in the downstream area. In the lower dammed Jinsha River, analysis of landscape indicators showed that the landscape was enriched, while the landscape type distribution was more uniform. Moreover, hydropower exploitation brought benefits to regional economic development. Principal component analysis further highlighted the landscape ecological and economic variations with high loadings in the first principal component. With the non-significant temporal variations and normal spatial fluctuations in flow discharge, the landscape pattern was basically stable, and the utilization of hydropower can be sustainable in the Jinsha River. In addition, hydropower development drove local economic development. Based on the integrated analysis of hydrological, landscape ecological, and economic assessment at the watershed scale, our results stressed the significance of hydropower exploitation in the Jinsha River. However, more attention should be paid to the warming climate during hydropower exploitation. These findings are valuable for the scientific planning of hydropower bases in watersheds with large-scale cascade dams, and have substantial implications for sustainable hydropower development.

Systematic evaluation for hydropower exploitation rationality in hydro-dominant area: A case study of Sichuan Province, China

Despite the considerable contribution of hydropower for meeting electricity demand and meanwhile achieving free carbon emission, the rationality of hydropower exploitation needs to be reassessed in the context of hydropower curtailment being severe in some hydro-dominant areas. In this paper, a two-stage fuzzy-stochastic chance-constrained interval (TFCI) regional energy system optimization model under multiple complexities is developed for systematically assessing the rationality of existing hydropower exploitation plan, and reflecting the tradeoff between system cost and reliability for Sichuan territory where the exploitable hydropower resources rank first in China. Results showed that the degree of hydropower overcapacity would become far more severe under the real existing energy structure planning. Instead of continuously boosting hydropower exploitation, proper limitation on hydropower installed capacity expansion to make other renewable energy obtain deserved promotion can effectively reduce system cost and improve the utilization efficiency of all the renewable technologies. The highest utilization efficiency of hydropower, wind power and solar power could achieve [90%, 100%], [100%, 100%], and [100%, 100%], respectively. The obtained results also indicated that greater uncertainty about system cost may have to be faced if policymakers aim to lower risk and enhance system reliability. Suggestions are provided for eliminating the irrationality of hydropower in Sichuan and other similar hydro-dominant regions based on above mentioned conclusions.

Operating Small Hydropower Plants in Greece under Intermittent Flow Uncertainty: The Case of Tsiknias River (Lesvos)

In arid and semi-arid parts of the world, river exploitation is intensive, involving water storage for irrigation or hydropower generation. In Greece, 100 small hydropower plants (SHPs) take advantage of less than 10% of the hydropower potential of low flow streams (<2 m3/s), a very small amount in relation to the 70% of the European Union. The energy policy of complete decarbonization of the country by 2023 on a national scale opens the road for new investments in SHP projects, especially in intermittent-flow streams of the Greek islands. Simulated flows by the Modello Idrologico SemiDistribuito in continuo (MISDc model) are used to construct the annual flow duration curve (FDC) to study and assess the hydropower potential of an intermittent stream (Tsiknias river, Lesvos, Greece). For Tsiknias River, but also for six other intermittent-flow rivers of Crete island, the capacity factor (CF), which represents the mean annual power of the hydropower plant, should remain >75% to exploit the river’s potential. The FDC and CF are essential in designing SHP projects in intermittent-flow streams with long no-flow periods. The development of public participatory approaches and a closer cooperation among policy makers and stakeholders should work to promote hydropower exploitation and accelerate licensing procedures.

Application of Geographical Information System in Environmental and Economic assessment of Run-of-river Hydropower in Central Vietnam

Conventional hydropower exploitation includes building large dams and reservoirs would pose significant impact to the environment. Recently there is trend to switch from building large hydropower plant to small and medium size, particular run-of-river hydropower plant. This study assesses the feasibility of installing run-of-hydropower scheme in the Vu Gia Thu Bon river basin with regards to the environmental and economic impact. The analysis was performed using GIS to identify the location of power plant that might have environmental constrains. The economic payback of each power plant was calculated and spotted on the digital maps. The methodology proposed in this study could be helpful for decision-makers in the preliminary identification of the most suitable locations to install run-of-river plants in the Vu Gia Thu Bon river basin.

Preliminary study on the exploitation plan of the mega hydropower base in the lower reaches of Congo River

There have been few studies on the hydropower exploitation plan for sections beyond the Inga hydropower project (HPP) in the lower reaches of the Congo River. Based on topographic and hydrological data of the basin, the exploitation plan for the lower reaches of the Congo River is herein studied. The preliminary proposal involves exploitation using three- cascade hydropower stations. The Grand Inga HPP is the core of the mega hydropower base. The full supply level (FSL) of the reservoir, installed capacity, and regulation performance of the Grand Inga HPP are studied in detail. The main advantages and disadvantages of the high and low dam schemes of the Grand Inga Hydropower Project are compared, in addition to their effects on the overall development of the hydropower base. Moreover, the installed capacity is optimized based on the load characteristics. Based on simulation of cascade hydropower operation and comprehensive analysis, the project scale and implementation sequence is proposed. The influence of hydropower on socio-economic development, energy supply, and emission reduction is analyzed. Finally, the optimal exploitation scheme of the mega hydropower base for the lower reaches of the Congo River is proposed.

Understanding the hydropower exploitation’s hydrological impacts through a len of change in flow-sediment relationship: A case study in the Han River Basin, China

The water and sediment yields of rivers are changing substantially under the impacts of climate variability and anthropogenic activities, which are increasingly becoming an important research topic in the field of hydro-environmental science. This study presents a comprehensive investigation of the changes in runoff depth (h), specific sediment yield (SSY), and flow-sediment relationship at multi-temporal scales in the Han River Basin (HRB). The effects of climate variability and anthropogenic activities on SSY were quantified by employing double cumulative curve analysis. The results are as follows: (1) The annual and flood season h and SSY in the midstream (Huangzhuang Station) during the past six decades presented declining trends. The detected change points (i.e., 1968 and 1984) in SSY were linked to the reservoir and dam construction and soil and water conservation programs. The Danjiangkou (DJK) Reservoir impounded water in the flood season and supplied water in the non-flood season, which made the intra-annual distributions of h and SSY more even and the intra-annual variations more moderate in the comparisons between the pre- and post-change periods. (2) The annual and flood-season flow-sediment relationships were fitted with the power function and the sediment productive ability of runoff in the flood season was much greater than that in the non-flood season. The construction and operation of the DJK Reservoir intercepted a significant quantity of sediment; thus, the sediment transported by unit runoff largely declined. (3) The estimated relative contributions of climate variability and anthropogenic activities to the changes in SSY suggested that the anthropogenic activities played a more substantial role in the SSY decline after the transition years. Sustainable development of the HRB will face many challenges as the water and sediment discharges decrease further from the Han River into the Yangtze River. These results will provide a reference for better soil and water resource conservation and draw more attention to strengthen the river basin management.

Impacts of climate change and human activities on the flow regime of the dammed Lancang River in Southwest China

The Lancang River (LR) in China (the upper portion of the Mekong River which is among the world’s most important transboundary rivers) originates on the Tibetan Plateau and provides important freshwater resources for living, agriculture, industry, and hydropower generation for millions of people downstream. The natural flow regime of the LR is critical to sustain native biodiversity and ecosystem integrity; however, it has been changing due to the combined effect of climate change and human activities. Accurate quantification of the impacts of climate change and human activities on changes in the flow regime is a prerequisite for water resources and hydropower exploitation and environmental protection. This study aims to evaluate climate- and human-induced impacts on the LR during 1980–2014. A distributed hydrological model CREST-snow combined with remote sensing and streamflow data and the Budyko framework were jointly used to address this scientific question during three time windows determined by the Mann–Kendall test and the history of dam construction. Results show that compared with the baseline period (1980–1986) when no dam was constructed, significant changes (∼−6%) in mean annual streamflow occurred during 1987–2014, particularly after 2008 when the construction of the largest hydropower plant (Nuozhadu) in the Mekong River basin began. Climatic change contributed ∼57% to streamflow changes during the transition period (1987–2007), whereas human activities contributed ∼95% during the post-impact period (2008–2014). At the seasonal scale, climatic variation plays a more significant role during the dry season (December–May), with precipitation the most important factor among climate variables, whereas human activities contributed more during the wet season (June–November), benefiting the downstream areas through mitigating floods. Among human activities, reservoir construction is a dominant factor affecting streamflow over agricultural, industrial, and domestic water uses. The findings of this study enhance our understanding of hydrological changes in the LR basin that may impact the Lower Mekong River, serve as a basis for water resources and hydropower exploitation and environmental protection, and highlight the need for considering reservoir operation strategies in streamflow projections in similar basins globally under climate change scenarios.

The value of satellite retrieved snow cover images to assess water resources and the hydropower potential of ungauged mountain areas

The estimation of water resources in ungauged areas is of major importance to develop adequate and sustainable water management strategies. Hydrological modelling can provide a powerful tool to assimilate hydro-meteorological data and estimate the total amount of water available from ungauged areas. Satellite images provide important information on the snow cover area in inaccessible mountain areas. The Hydrologiska Byråns Vattenbalansavdelning model (HBV) was used to estimate the total amount of snow, ice and rainfall runoff in two ungauged areas in north-eastern Iceland (Leirdalshraun, a 274 km² area above 595 m a.s.l. and Heljardalsfjöll, a 946 km² area above 235 m a.s.l.) that could potentially be used for hydropower production. The model parameters were determined using a multiple dataset calibration (MDC) relying on one year of satellite derived snow cover images and discharge data of gauged sub-catchments. Runoff from the ungauged area potentially used for hydropower exploitation was estimated using the parameter sets of the gauged sub-catchments. Snow cover in the ungauged areas as well as discharge in the gauged sub-catchments were validated over a 10 year validation period, revealing a robust simulation of snow melt in the entire area. The total amount of snow-melt, ice-melt and rainfall runoff available in Leirdalshraun and Heljardalsfjöll amounts up to ∼690 M m³ a$^{−1}$ and ∼1190 M m³ a$^{−1}$ , respectively. The theoretical potential energy of these water resources would account for up to 1.9 TWh a$^{−1}$, a tremendous hydropower potential if the water could be collected in respective reservoirs and be deviated to turbines at sea-level. While the results are only valid for the specific case study, the modelling approach can be applied to any remote mountain area dominated by snow melt runoff.

Heating Impact of a Tropical Reservoir on Downstream Water Temperature: A Case Study of the Jinghong Dam on the Lancang River

Reservoirs change downstream thermal regimes by releasing water of different temperatures to that under natural conditions, which may then alter downstream biodiversity and ecological processes. The hydropower exploitation in the mainstream Lancang-Mekong River has triggered concern for its potential effects on downstream countries, especially the impact of the released cold water on local fishery production. However, it was observed recently that the annual water temperature downstream of the Jinghong Reservoir (near the Chinese border) has increased by 3.0 °C compared to its historical average (1997–2004). In this study, a three-dimensional (3D) model of the Jinghong Reservoir was established to simulate its hydro- and thermodynamics. Results show that: (1) the impoundment of the Jinghong Reservoir contributed about 1.3 °C to the increment of the water temperature; (2) the solar radiation played a much more important role in comparison with atmosphere-water heat exchange in changing water temperatures; and (3) the outflow rate also imposed a significant influence on the water temperature by regulating the residence time. After impoundment, the residence time increased from 3 days to 11 days, which means that the duration that the water body can absorb solar radiation has been prolonged. The results explain the heating mechanism of the Jinghong Reservoir brought to downstream water temperatures.

Future changes in Yuan River ecohydrology: Individual and cumulative impacts of climates change and cascade hydropower development on runoff and aquatic habitat quality

The eco-hydrological system in southwestern China is undergoing great changes in recent decades owing to climate change and extensive cascading hydropower exploitation. With a growing recognition that multiple drivers often interact in complex and nonadditive ways, the purpose of this study is to predict the potential future changes in streamflow and fish habitat quality in the Yuan River and quantify the individual and cumulative effect of cascade damming and climate change. The bias corrected and spatial downscaled Coupled Model Intercomparison Project Phase 5 (CMIP5) General Circulation Model (GCM) projections are employed to drive the Soil and Water Assessment Tool (SWAT) hydrological model and to simulate and predict runoff responses under diverse scenarios. Physical habitat simulation model is established to quantify the relationship between river hydrology and fish habitat, and the relative change rate is used to assess the individual and combined effects of cascade damming and climate change. Mean annual temperature, precipitation and runoff in 2015–2100 show an increasing trend compared with that in 1951–2010, with a particularly pronounced difference between dry and wet years. The ecological habitat quality is improved under cascade hydropower development since that ecological requirement has been incorporated in the reservoir operation policy. As for middle reach, the runoff change from January to August is determined mainly by damming, and climate change influence becomes more pronounced in dry seasons from September to December. Cascade development has an effect on runoff of lower reach only in dry seasons due to the limited regulation capacity of reservoirs, and climate changes have an effect on runoff in wet seasons. Climate changes have a less significant effect on fish habitat quality in middle reach than damming, but a more significant effect in lower reach. In addition, the effect of climate changes on fish habitat quality in lower reach is high in dry seasons but low in flood seasons.