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Water Availability Issues for the St. Lawrence River: An Environmental Synthesis.

Talbot, A. (ed.) (2006). Water Availability Issues for the St. Lawrence River: An Environmental Synthesis. [Publication gouvernementale]

Talbot (ed.)_2006. Water Availability_SLR_ Environmental_Synthesis_A.pdf

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Fluctuating flow and water levels in the St. Lawrence River, whether natural or human-induced, are of concern to the various stakeholders (government organizations, research scientists, industries and the general public) that have been involved for several years in managing water resources and their use, and in maintaining the physical chemical and biological integrity of the ecosystem. Such concerns are particularly justified in the current context of climate change, which is likely to significantly influence socio-economic and environmental policy decisions. In recent years, Environment Canada research scientists have been studying the problem of fluctuating flows and water levels in the fluvial portion of the St. Lawrence. Much of their research has been carried out in the context of the work of the International Joint Commission and, more specifically, the International Lake Ontario–St. Lawrence River Study Board, which has a mandate to evaluate the procedures and criteria used to regulate outflows from Lake Ontario and manage water levels in Lake Ontario and the St. Lawrence River. This document is the product of the work of several of the above-mentioned Environment Canada research scientists. It is a synthesis of the current state of knowledge and of certain recommendations relating to the possible impacts of fluctuating flows and water levels on various environmental and socio-economic factors. The following is a brief summary of each of the 13 chapters of the report. Chapter 1 describes the issue of water availability for the St. Lawrence. The authors summarize the major changes that have occurred in the Great Lakes–St. Lawrence system and present the institutional framework applicable to fluctuating water levels in the St. Lawrence. They review the various laws, policies and federal-provincial agreements regarding water resources and flood control, wetland conservation, fish habitat management, species at risk, etc. They then provide a historical account of efforts to review the management of water levels in the St. Lawrence. The chapter ends with a discussion of the current challenges and issues relating to the sustainability of the St. Lawrence ecosystem. Chapter 2 provides a synthesis of the current state of knowledge of the physiographic and hydrological characteristics of the fluvial section of the St. Lawrence downstream of Cornwall. It describes the various components (flow, inflows, anthropogenic features, the seaway, ice management, regulation, etc.) and the fluctuating flows (short-term, seasonal and long-term) and water levels. Chapter 3 covers the dominant physical processes at play in the St. Lawrence River, the modelling of these processes and the integration of the resulting models in an ecosystem modelling system. On the basis of topometric information, bedrock and aquatic vegetation mapping and analysis of the fluvial hydrology, the authors present the steps involved in and results of the modelling of currents, waves, water masses and other physical variables that are important to the analysis and modelling of flora and fauna. Chapter 4 deals with the modelling of the spatial distribution of and temporal changes in the aquatic vegetation of the St. Lawrence River. On the basis of information derived from physical changes as a function of flow and from a very large number of field observations, the authors show how modelling is used to understand changes in the aquatic vegetation and major wetland classes along the river’s edge. Chapter 5 studies the effects of the St. Lawrence River hydrological regime on plant diversity and productivity. The author presents in detail the characteristics of each of the primary producer compartments (phytoplankton, metaphyton, periphyton, and macrophytes) from the point of view of biodiversity, biomass and productivity. The author also discusses temporal variations as a function of water levels and threats to the integrity of organisms and their habitats posed by human activities (excavation of the river bed and basin tributaries, regulation and dams) and climate change. Chapter 6 concentrates on the impacts of fluctuating water levels on reptiles and amphibians. The author reviews the direct and indirect effects of a decrease or increase in water levels on the various species of reptiles and amphibians that occur in the St. Lawrence Valley. The author also discusses the anticipated effects of climate change and gives an overview of the other environmental pressures on the herpetofauna of the St. Lawrence (i.e. habitat fragmentation, chemical pollution, infectious diseases, introduced species, etc.). Chapter 7 focusses on fish communities in the lower St. Lawrence River. The authors analyze how the nature and the extent of hydrological variability influence fish dynamics and attempt to provide a prognosis in terms of the potential effects of regulation on ecosystem integrity and the dynamics of fish communities in the river. Chapter 8 examines wetland birds. The authors provide a current picture of the bird species and habitats of the St. Lawrence and go on to analyze the role of fluvial dynamics on bird assemblages. One section is devoted specifically to species at risk. The chapter concludes with recommendations concerning the regulation of water levels for the benefit of bird species. Chapter 9 presents a discussion of the muskrat, the only herbivorous mammal that has a direct impact on the dynamics of St. Lawrence wetlands. The authors cover certain aspects of the biology of this mammal and its interaction with wetlands before addressing the impacts of water-level fluctuations in winter and the ecological implications of regulating St. Lawrence River flows. Chapter 10 looks specifically at species at risk. The author presents the current situation on the fluvial section of the St. Lawrence and the legislation protecting species at risk, followed by a section on species at risk whose survival depends on hydrological conditions. The author then discusses the performance of regulation plans from the perspective of various species and concludes with a number of recommendations aimed at improving our understanding and limiting the negative impacts of waterlevel fluctuations on these species. Chapter 11 addresses St. Lawrence water use. The authors review the main water requirements for human activities (public supply, hydroelectric power generation, commercial shipping and recreational boating, etc.) and discuss the threats and issues associated with water availability. The authors conclude by evaluating the role of the adaptations to be considered to counteract human pressure on water resources. Chapter 12 describes the concept of performance indicators and the various methods and approaches used to evaluate the regulation plans that have been proposed to replace the current plan. The chapter concludes with an overview of the research that remains to be done. Chapter 13 presents the overall prospects for an integrated approach to the management of the waters of the St. Lawrence. The authors discuss the scientific base and the multiplicity of players and users as agents of integrated management. They conclude by providing a number of directions for the development of policy capacity and strategies based on comprehensive integration.

Type de document: Publication gouvernementale
Nombre de pages: 206
Éditeur: Environment Canada, Minister of the Environment
Lieu de publication: Montréal
Statut du texte intégral: Public
Mots-clés libres: Water availability, St. Lawrence River, Performance indicators, Modelling, Socio-economic dimension, Species at risk, Water levels, Aquatic mammal, Wetland birds, Hydrological regime, Fish communities, Habitats, Reptiles, Amphibians, Aquatic plant communities, Wetlands, Anthropogenic modifications
Sujets: 2. Milieu physique > 2.4. Hydrologie
3. Végétation, milieux humides > 3.2. Herbier aquatique
3. Végétation, milieux humides > 3.3. Marais
4. Faune > 4.2. Poisson
4. Faune > 4.3. Amphibien
4. Faune > 4.4. Oiseaux
4. Faune > 4.5. Mammifère
8. Impacts et monitoring > 8.6. Synthèse des connaissances
8. Impacts et monitoring > 8.7. Modélisations et indicateurs
Date de dépôt: 09 mai 2017 19:48
Dernière modification: 09 mai 2017 19:48
ISBN: 0-662-44382-9

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