Limiting the effects of hydropower dams on freshwater biodiversity: options on the Lancang River, China

2019 ◽  
Vol 70 (2) ◽  
pp. 169 ◽  
Author(s):  
Hongzhang Xu ◽  
Jamie Pittock
Keyword(s):  
Pollution Control ◽  
Fish Fauna ◽  
Mitigation Measures ◽  
Main Stream ◽  
Migratory Species ◽  
Freshwater Biodiversity ◽  
Lancang River ◽  
Hydropower Dams ◽  
Different Types ◽  
International Importance

China has planned 23 dams on the main stream of the Lancang (upper Mekong) River. The Chinese Government’s Thirteenth Five-Year Plan on Hydroelectricity Development (TFP) has goals to mitigate adverse effects on freshwater biodiversity. These measures are of international importance because China is the largest developer of hydropower projects. Herein we analyse the effects of the existing and planned dams on the fish fauna in the Lancang River. Drawing on development documents, the different types of mitigation measures on the proposed cascade of dams are assessed against the goals of the TFP. We find that: (1) migratory species (25% of total) are severely affected and there are few effective mitigation measures to conserve them; (2) a further 20% of species may be affected by lack of thermal pollution control or mitigation of peaking flow releases in the main stream; (3) fortunately, most species (81.14%) can be protected in tributary nature reserves in the lower Lancang, but many (54.4%) are inadequately protected in the upper Lancang; and (4) none of the 20 dams for which there is information meet all the five TFP conservation goals. There are lessons for mitigating the effects on biodiversity of Chinese-financed hydropower dams inside and outside China.

Community Ecology of Stream Fishes: Concepts, Approaches, and Techniques

2010 ◽  
Keyword(s):  
Life History ◽  
Food Web ◽  
Interaction Strength ◽  
Ecosystem Dynamics ◽  
Stream Fishes ◽  
Migratory Fish ◽  
Migratory Species ◽  
Different Types ◽  
Migratory Stream ◽  
Migratory Fishes

<em>Abstract</em>.—Migratory fishes are common in freshwaters throughout the world and can fundamentally alter recipient ecosystems. We describe different types of fish migrations and consider their importance from the perspective of ecosystem subsidies—that is, landscape-scale flows of energy, materials, and organisms that are important in driving local food web and ecosystem dynamics. We distinguish between two general categories of subsidies, which we term here material subsidies and process subsidies. Material subsidies are the transfer of energy, nutrients, and other resources resulting in direct changes in resource pools within ecosystems. We posit that material subsidies occur under only a subset of life history strategies and ecological settings, and the potential for migratory fish to represent major material subsidies is greatest when (1) the biomass of migrants is high relative to recipient ecosystem size, (2) the availability of nutrients and energy is low in the recipient ecosystem (i.e., oligotrophic), and (3) there are effective mechanisms for both liberating nutrients and energy from migratory fishes and retaining those materials within the food web of the recipient ecosystem. Thus, anadromous semelparous Pacific salmon <em>Oncorhynchus </em>spp. with en masse programmed senescence in oligotrophic Pacific Northwest streams can be large material subsidies. In contrast, process subsidies arise from feeding or other activities of migratory species that directly affect process rates within recipient ecosystems. For example, the physical and chemical effects of grazing and sediment-feeding fishes such as prochilodontids, as well as seed dispersal by large-bodied frugivorous characins, represent potentially key process subsidies by migratory fishes in some of the great rivers of South America. We speculate that process subsidies are more widespread than material subsidies from migratory stream fishes because they are independent of the type of migration patterns, life history, and distance traveled. Nevertheless, the magnitude of process subsidies is likely to be greatest under a specific subset of ecological conditions, which can differ from those where material subsidies might be most important. In addition to migrant biomass, the potential for migratory fish to represent strong process subsidies is regulated by migrant interaction strength and the degree to which a migratory species is functionally unique in a particular ecological setting. Unlike material subsidies, which require high migrant biomass as conveyor belts of materials, migratory fishes can be crucial process subsidies, even when migrant biomass is low, if they are functionally unique and strong interactors. We provide specific examples of these different types of subsidies and outline key directions of research for furthering our understanding of the functional significance of migratory stream fishes. Our aim is to highlight the diversity of subsidies provided by migratory fishes in order to foster a more comprehensive perspective on fishes as essential components of riverine ecosystems.

scholarly journals Predicting Extreme-Precipitation Effects on the Geomorphology of Small Mountain Catchments: Towards an Improved Understanding of the Consequences for Freshwater Biodiversity and Ecosystems

Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 79 ◽  
Author(s):  
Stefano Segadelli ◽  
Federico Grazzini ◽  
Michele Adorni ◽  
Maria Teresa De Nardo ◽  
Anna Fornasiero ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Debris Flows ◽  
Mitigation Measures ◽  
Convective System ◽  
Stream Channels ◽  
Freshwater Biodiversity ◽  
Rainfall Analysis ◽  
Extreme Precipitation Events ◽  
Hourly Rainfall ◽  
Precipitation Events

In 2015 an intense rainfall event hit the Valleys of the Trebbia, Nure, and Aveto watercourses in the Northern Apennines. In about 6 h a mesoscale convective system deployed a stunning amount of precipitation of 340 mm, with an extreme hourly rainfall intensity of >100 mm/h. It triggered debris flows along slopes and stream channels, landslides and floods, which caused serious damages. Through the optimal combination of rainfall data and radar volumes, in this work we present a detailed rainfall analysis, which will serve as a basis to create a quantitative correlation with debris flows over elementary hydrological units. We aim at providing an objective basis for future predictions, starting from the recognition of the forcing meteorological events, and then arriving at the prediction of triggering phenomena and to the debris-flow type. We further provide seven observations/case studies on the effects of extreme-precipitation events on freshwater environments in small mountain catchments. Extreme-precipitation events are becoming more frequent and widespread globally but their ecological effects are still insufficiently understood. In general, the effects of extreme events on inland-waters’ ecosystems are highly context-dependent, ranging from deleterious to beneficial. We therefore highlight the necessity of further studies to characterize these effects in more depth to be able to include appropriate mitigation measures in environmental planning and stewardship.

scholarly journals Spatial Variation and Controlling Factors of H and O Isotopes in Lancang River Water, Southwest China

2019 ◽  
Vol 16 (24) ◽  
pp. 4932 ◽  
Author(s):  
Kunhua Yang ◽  
Guilin Han ◽  
Jie Zeng ◽  
Bin Liang ◽  
Rui Qu ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
River Water ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Water Security ◽  
Controlling Factors ◽  
Main Stream ◽  
Wet Season ◽  
Lancang River ◽  
O Isotopes

Climate changes and other human activities have substantially altered the hydrological cycle with respect to elevation. In this study, longitudinal patterns in the stable isotopic composition (δ2H and δ18O) of Lancang River water, originating from the Qinghai–Tibetan Plateau, are presented, and several controlling factors in the wet season are hypothesized. Lancang River water δ2H (−145.2‰ to −60.7‰) and δ18O (−18.51‰ to −8.49‰) were low but close to those of the Global Meteoric Water Line. In the upper reaches of the river, δ2H decreased longitudinally, potentially due to groundwater inputs and melting ground ice in the headwater zone and to an increasing proportion of glacier meltwater with decreasing elevation. In the middle reaches of the river, δ2H values increased slowly moving downstream, likely due to shifts in precipitation inputs, as evidenced by the isotopic composition of tributaries to the main stream. In the lower reaches of the river, the isotopic composition was relatively invariant, potentially related to the presence of large artificial reservoirs that increase the water resident time. The results reveal different hydrological patterns along an alpine river in central Asia associated with both natural and anthropogenic processes. Understanding the degree and type of human interference with the water cycle in this region could improve water management and water security.

scholarly journals Efficiency and selectivity of a trap and truck fish passage system in Brazil

2007 ◽  
Vol 5 (2) ◽  
pp. 169-176 ◽  
Author(s):  
Paulo dos Santos Pompeu ◽  
Carlos Barreira Martinez
Keyword(s):  
Original Composition ◽  
Species Composition ◽  
Fish Fauna ◽  
Marine Species ◽  
Fish Passage ◽  
Reproductive Period ◽  
Reproductive Season ◽  
Migratory Species ◽  
Composition And Structure ◽  
River Fish

The construction of fish passages has been one of the strategies adopted by the Brazilian energy sector in order to diminish the effects of barriers on fish communities. However, studies of the efficiency of these mechanisms are scarce. The present study evaluated the efficiency and selectivity of the first trap and truck fish passage system in Brazil, installed in Santa Clara Dam, Mucuri River. The species composition in the Santa Clara Dam fish lift was compared to the original composition of Mucuri River fish fauna and with the populations that gather downstream of the dam during the reproductive season. The proportion of previously tagged individuals translocated by the lift was used to estimate its efficiency. During the 2003/2004 reproductive period, 67,841 individuals of 32 species passed through the lift, which corresponds to 66% of the lower Mucuri river fish richness. Less than 0.5% died or were injured during the passage. When compared to the river's population, less representative captures of smaller individuals and marine species were observed. However, the composition and structure of the community in the fish lift was quite similar to those downstream of the dam during the reproductive season. The estimated efficiency of the fish lift ranged from 0.2% for Pogonopoma wertheimeri to 16.1% for Leporinus conirostris reaching an average of 7% for all migratory species.

Development of Small Businesses During Economic Crises

2021 ◽  
pp. 1-26
Author(s):  
tulus tambunan
Keyword(s):  
Financial Crisis ◽  
Small Businesses ◽  
Global Financial Crisis ◽  
Mitigation Measures ◽  
Economic Crises ◽  
Literature Study ◽  
Transmission Channels ◽  
Different Types ◽  
Data Collection Technique ◽  
The Impact

This is a descriptive study that aims to estimate the impact of three economic crises (i.e., the 1997/98 Asian financial crisis, the 2008/09 global financial crisis, and the COVID-19 pandemic crisis) on small businesses in Indonesia and to explore their crisis mitigation measures (CMMs). It adopted an exploratory methodology with comprehensively reviewing the available literature (e.g., policy documents, research papers, and reports) on the subject being studied. The data collection technique applied was literature study. It shows that different types of crises have different transmission channels through which such crises affected small businesses. CMMs adopted by affected small businesses also vary by different types of crises and hence different business risks. To the best of author's knowledge, this is the first study that examines transmission channels through which such crises affected small businesses in Indonesia.

scholarly journals Fish community structure of Juramento reservoir, São Francisco River basin, Minas Gerais, Brazil

2006 ◽  
Vol 23 (3) ◽  
pp. 832-840 ◽  
Author(s):  
André R. M. Silva ◽  
Gilmar B. Santos ◽  
Thiago Ratton
Keyword(s):  
Community Structure ◽  
Native Species ◽  
Fish Community ◽  
Fish Fauna ◽  
Fish Abundance ◽  
Fish Community Structure ◽  
Migratory Species ◽  
Wet Season ◽  
Dry Period ◽  
The Relationship

Many rivers in Brazil as the São Francisco (SFR) have been impounded for reservoirs construction purposes. However, there is a lack of knowledge on their fish fauna in many areas, including headwaters. The present study aimed to describe the fish community structure from Juramento reservoir, located on Juramento River, a branch of SFR basin. Six bimonthly samplings were made in four different sites. Gill and cast nets, beach seines and sieves were used to collect fish. Ecological indexes as well as the relationship between fish abundance and some limnological variables were determined. 3288 fish belonging to 33 species (16.5% of the total described for SFR basin) were captured, being 75.7% Characiformes, 18.1% Siluriformes, 3% Cyprinodontiformes and 3% Gymnotiformes. Only two non-native species, 'tamboatá' - Hoplosternum littorale (Hancock, 1828) and 'trairão' - Hoplias lacerdae Ribeiro, 1908 were found. The highest catches in number occurred in the dry period (March-October) and the lowest one in the wet season (November-February). Diversity was higher at Barragem station and richness did not vary between reservoir zones. Five migratory species were found downstream of the dam (four exclusively there), whereas only the 'curimbatá-pioa' - Prochilodus costatus Valenciennes, 1850 occurred in the reservoir. The low observed correlations between fish abundance and the limnological variables utilized suggest that the local fish fauna is not strongly affected by their variation.

A Manœuvre Criterion

1964 ◽  
Vol 17 (4) ◽  
pp. 358-363
Author(s):  
J. B. Parker
Keyword(s):  
Statistical Treatment ◽  
Technical Committee ◽  
Main Stream ◽  
Random Errors ◽  
Different Types ◽  
Observational Errors ◽  
Systematic And Random Errors

The consideration of the effect of observational errors on the problem of manoeuvring ships at sea has, surprisingly enough, only recently become the object of attention by contributors to this Journal, though the basic background was provided many years ago by Sadler. The discussion at the Technical Committee of the Institute emphasized the importance of a statistical treatment of the problem and this led first to a brief note by myself in which systematic and random errors in range and bearing were discussed, and later to a full survey by Hollingdale in which it was shown that the total time to the instant of closest approach should be divided between observing time and manoeuvring time. An article by Proctor, though rather out of the main stream of the ideas pursued by the above mentioned contributors, breaks new ground in the sense that comparisons are made between different types of manœuvre on a probabilistic basis.

scholarly journals A new rating system for hydrogeological risk management along railway infrastructures in Prealpine zone (northern Italy)

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
P. Gattinoni ◽  
L. Scesi ◽  
L. Arieni ◽  
M. Canavesi ◽  
F. Zaffaroni
Keyword(s):  
Heuristic Method ◽  
Northern Italy ◽  
Rating System ◽  
Mitigation Measures ◽  
Mountain Areas ◽  
Different Types ◽  
Slope Instabilities ◽  
Definition Of ◽  
Critical Sections ◽  
Risk Analysis And Management

AbstractRailway infrastructures in mountain areas often develop along hillslopes affected by geomorphological and hydrogeological processes which might lead hazardous events. Therefore, specific tools for risk analysis and management are required. This paper develops a new rating system (Railway Hydrogeological Management System, RHMS), based on a heuristic method which considers the susceptibility to different types of slope instabilities, as well as the peculiar features affecting the railway vulnerability. The proposed method introduces an iterative approach for the risk assessment, based on the definition of acceptability thresholds for the residual risk. The application of this method to a test area pointed out its feasibility, as well as its operational capability to identify the critical sections of the infrastructure, in which protection or mitigation measures are needed in order to reduce the risk.

scholarly journals Dealing with Culturally Sensitive Areas in Industrial Project Design

2012 ◽  
Vol 3 (2) ◽  
Author(s):  
Alan Ehrlich
Keyword(s):  
Culturally Sensitive ◽  
Mitigation Measures ◽  
Aboriginal Peoples ◽  
Major Influence ◽  
Project Design ◽  
Project Proposal ◽  
Industrial Project ◽  
Sensitive Areas ◽  
Cultural Impacts ◽  
Different Types

Potential cultural impacts from proposed industrial developments can affect culturally sensitive areas that are important to Aboriginal peoples. These cultural impacts are important for legal, political, and moral reasons and can have a major influence on project approval or rejection during environmental impact assessment. It is in the interest of developers to identify and consider potential impacts on culturally sensitive areas early in the project proposal process in order to design projects that minimize or avoid these impacts. A key strategy is to engage communities effectively in the process. Different types of mitigation measures, including off-site cultural mitigation, may be appropriate for different types of culturally sensitive areas, but avoidance may be the only option for certain non-negotiable areas.

scholarly journals The impacts of hydropower on freshwater macroinvertebrate richness: A global meta-analysis

2021 ◽  
Author(s):  
Gabrielle Trottier ◽  
Katrine Turgeon ◽  
Daniel Boisclair ◽  
Cécile Bulle ◽  
Manuele Margni
Keyword(s):  
Variance Estimation ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Hydroelectric Dams ◽  
Freshwater Biodiversity ◽  
Mixed Effect ◽  
Large Variability ◽  
Effect Model ◽  
Hydropower Dams ◽  
Study Designs

AbstractHydroelectric dams and their reservoirs have been suggested to affect freshwater biodiversity. However, studies investigating the consequences of hydroelectric dams and reservoirs on macroinvertebrate richness have reached opposite conclusions. We carried out a meta-analysis devised to elucidate the effects of hydropower dams and their reservoirs on macroinvertebrates richness while accounting for the potential role played by moderators such as biomes, impact types, study designs, sampling seasons and gears. We used a random and mixed effect model, combined with robust variance estimation, to conduct the meta-analysis on 72 pairs of observations (i.e., impacted versus reference) extracted from 17 studies (more than one observation per study). We observed a large range of effect sizes, from very negative to very positive impacts of hydropower. However, according to this meta-analysis, hydropower dams and their reservoirs did not have an overall clear, directional and statistically significant effect on macroinvertebrate richness. We tried to account for the large variability in effect sizes using moderators, but none of the moderators included in the meta-analysis had statistically significant effect. This suggests that some other moderators, which were unavailable for the 17 studies included in this meta-analysis, might be important (e.g., temperature, granulometry, wave disturbance and macrophytes) and that macroinvertebrate richness may be driven by local, smaller scale processes. As new studies become available, it would be interesting to keep enriching this meta-analysis, as well as collecting local habitat variables, to see if we could finally draw statistically significant conclusions about the impacts of hydropower on macroinvertebrate richness.

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