Editorial: Environmental flows in an uncertain future (original) (raw)
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Freshwater ecosystem services supporting humans: Pivoting from water crisis to water solutions
Global Environmental Change, 2015
A new global scale water indicator, the freshwater provisioning index for humans (FPI h ), maps the capacity of upstream source areas to provide water for human populations downstream. The freshwater provisioning index for humans combined with estimates of threats to water source areas assesses the compounded impacts on freshwater provisions at their point-of-service and the humans they support downstream. Nearly the entire world is serviced by freshwater sources compromised to a moderate extent through human activities, with 82% of the world's population served by upstream areas exposed to high levels of threat. Globally, 75% of the world's population benefits from engineered remediation of highly impaired source areas. Despite these gains, more than 80% of the global population still experiences moderate levels of threat impacting their freshwater provisions. Industrialized nations greatly limit their exposure to threats via infrastructure investments whereas regions in the developing world with moderate threat and little means of mitigation are viewed as the most vulnerable. Populations served by water source areas in industrialized countries receive highest threat reductions overall (50-70%) while those served by provision areas in the least developed countries receive <20% threat decrease. Better management of upstream source areas in poorer countries represents an opportunity to reduce threat lessening reliance on costly engineering solutions. Viewing the world in terms of the threats imposed on freshwater provisions combined with regional capacity to abate these impairments through infrastructure investments yields a spatial typology of freshwater resource development states reflecting region-specific challenges with unique management implications. Global mapping of threat development states provides a synoptic-scale diagnosis of key water resource challenges we link with state-specific water service management strategies including service area conservation, threat reduction, and green and gray infrastructure investments to more sustainably manage upstream freshwater provisions. This study provides a functional architecture to assess potential investment strategies to sustainably protect and manage critical upstream freshwater provisions addressing unique challenges faced by different regions of the world.
Ecologically sustainable water management: managing river flows for ecological integrity
Ecological …, 2003
Human demands on the world's available freshwater supplies continue to grow as the global population increases. In the endeavor to manage water to meet human needs, the needs of freshwater species and ecosystems have largely been neglected, and the ecological consequences have been tragic. Healthy freshwater ecosystems provide a wealth of goods and services for society, but our appropriation of freshwater flows must be better managed if we hope to sustain these benefits and freshwater biodiversity. We offer a framework for developing an ecologically sustainable water management program, in which human needs for water are met by storing and diverting water in a manner that can sustain or restore the ecological integrity of affected river ecosystems. Our six-step process includes: (1) developing initial numerical estimates of key aspects of river flow necessary to sustain native species and natural ecosystem functions; (2) accounting for human uses of water, both current and future, through development of a computerized hydrologic simulation model that facilitates examination of human-induced alterations to river flow regimes; (3) assessing incompatibilities between human and ecosystem needs with particular attention to their spatial and temporal character; (4) collaboratively searching for solutions to resolve incompatibilities; (5) conducting water management experiments to resolve critical uncertainties that frustrate efforts to integrate human and ecosystem needs; and (6) designing and implementing an adaptive management program to facilitate ecologically sustainable water management for the long term. Drawing from case studies around the world to illustrate our framework, we suggest that ecologically sustainable water management is attainable in the vast majority of the world's river basins. However, this quest will become far less feasible if we wait until water supplies are further over-appropriated.
Science of The Total Environment, 2015
This paper considers the impacts of land use and hydrological intensification on inland waters • Global issues are considered through the lens of Australian examples • Likely scenarios include wet regions becoming wetter, dry regions drier and storms more intense • The legacies of past land use change will need to be addressed • Proactive governance based on innovative science and adaptive management will be critical a b s t r a c t Intensification of the use of natural resources is a world-wide trend driven by the increasing demand for water, food, fibre, minerals and energy. These demands are the result of a rising world population, increasing wealth and greater global focus on economic growth. Land use intensification, together with climate change, is also driving intensification of the global hydrological cycle. Both processes will have major socio-economic and ecological implications for global water availability. In this paper we focus on the implications of land use intensification for the conservation and management of freshwater ecosystems using Australia as an example. We consider this in the light of intensification of the hydrologic cycle due to climate change, and associated hydrological scenarios that include the occurrence of more intense hydrological events (extreme storms, larger floods and longer droughts). We highlight the importance of managing water quality, the value of providing environmental flows within a watershed framework and the critical role that innovative science and adaptive management must play in developing proactive and robust responses to intensification. We also suggest research priorities to support improved systemic governance, including adaptation planning and management to maximise freshwater biodiversity outcomes while supporting the socioeconomic objectives driving land use intensification. Further research priorities include: i) determining the relative contributions of surface water and groundwater in supporting freshwater ecosystems; ii) identifying and protecting freshwater biodiversity hotspots and refugia; iii) improving our capacity to model hydro-ecological relationships and predict ecological outcomes from land use intensification and climate change; iv) developing an understanding of long term ecosystem behaviour; and v) exploring systemic approaches to enhancing governance systems, including planning and management systems affecting freshwater outcomes. A major policy challenge will be the integration of land and water management, which increasingly are being considered within different policy frameworks.
Meeting Ecological and Societal Needs for Freshwater
Ecological …, 2008
Human society has used freshwater from rivers, lakes, groundwater, and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilization for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life-and these are costly, if not impossible, to replace. Long-term benefits include the sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations, such as climate change. Thus, maintenance of the processes and properties that support freshwater ecosystem integrity should be included in debates over sustainable water resource allocation.
Securing water for ecosystems and human well-being: The importance of environmental flows
• 21 st Century water resource managers are called upon to maximise the economic and social welfare of water users in an equitable manner without compromising the sustainability of vital ecosystems. This requires managers to view human well-being in a broader context and to recognise the multiple ways that people, especially the poor, depend on ecosystems and the services they provide. This includes basic elements of survival, improved community health, enhanced security, and better social relations. The services maintained by ecosystems have real economic values that are generally neglected in project cost-benefit analyses. These values are linked to the products provided by ecosystems as well as the avoidance of costs related to declining profits, remedial measures, damage repair, and health care. Healthy aquatic ecosystems are also to be valued for their adaptability and greater resilience in the face of climate change. • The quantity, quality and timing of water flows required to sustain ecosystems and the valuable services they provide are referred to as Environmental Flows. For river and wetland ecosystems, the flow regime is the most important determinant of ecosystem function and services provided by these functions. Flow features are determined by river size, geology, climate variation, topography and vegetation cover. The different components of an environmental flow regime contribute to different ecological processes. For example, base flows help maintain water Commission on Dams 2000). The parallel impacts on aquatic and riparian ecosystems are manifest in an alarming decline in freshwater biodiversity and the more ubiquitous and insidious degradation of ecosystem functions (WWF, 2008). The motivation for these expanded goals partially grew out of a recognition that people depend on aquatic ecosystems for far more than water, energy, and transportation.
Protecting the world's freshwater resources requires diagnosing threats over a broad range of scales, from global to local. Here we present the first worldwide synthesis to jointly consider human and biodiversity perspectives on water security using a spatial framework that quantifies multiple stressors and accounts for downstream impacts. We find that nearly 80% of the world's population is exposed to high levels of threat to water security. Massive investment in water technology enables rich nations to offset high stressor levels without remedying their underlying causes, whereas less wealthy nations remain vulnerable. A similar lack of precautionary investment jeopardizes biodiversity, with habitats associated with 65% of continental discharge classified as moderately to highly threatened. The cumulative threat framework offers a tool for prioritizing policy and management responses to this crisis, and underscores the necessity of limiting threats at their source instead of through costly remediation of symptoms in order to assure global water security for both humans and freshwater biodiversity. Water is widely regarded as the most essential of natural resources, yet freshwater systems are directly threatened by human activities 1–3 and stand to be further affected by anthropogenic climate change 4. Water systems are transformed through widespread land cover change, urbanization , industrialization and engineering schemes like reservoirs, irrigation and interbasin transfers that maximize human access to water 1,5. The benefits of water provision to economic productivity 2,6 are often accompanied by impairment to ecosystems and biodiversity, with potentially serious but unquantified costs 3,7,8. Devising interventions to reverse these trends, including conventions 9 and scientific assessments 10 to protect aquatic biodiversity and ensure the sustainability of water delivery systems 11 , requires frameworks to diagnose the primary threats to water security at a range of spatial scales from local to global. Water issues feature prominently in assessments of economic development 6 , ecosystem services 3 , and their combination 12–14. However, worldwide assessments of water resources 2 rely heavily on fragmented data often expressed as country-level statistics, seriously limiting efforts to prioritize their protection and rehabilitation 15. High-resolution spatial analyses have taken understanding of the human impact on the world's oceans 16,17 and the human footprint on land 18 to a new level, but have yet to be applied to the formal assessment process for freshwater resources 2 despite a recognized need 19,20. The success of integrated water management strategies depends on striking a balance between human resource use and ecosystem protection 2,9,10,21. To test the degree to which this objective has been advanced globally, and to assess its potential value in the future, requires systematic accounting. An important first step is to develop a spatial picture of contemporary incident threats to human water security and biodiversity, where the term 'incident' refers to exposure to a diverse array of stressors at a given location. Many stressors threaten human water security and biodiversity through similar pathways, as for pollution, but they also influence water systems in distinct ways. Reservoirs, for example, convey few negative effects on human water supply, but substantially impact on aquatic biodiversity by impeding the movement of organisms, changing flow regimes and altering habitat. Similarly, non-native species threaten biodiversity but are typically inconsequential to human water security. Here we report the results of a global-scale analysis of threats to fresh water that, for the first time, considers human water security and biodiversity perspectives simultaneously within a spatial accounting framework. Our focus is on rivers, which serve as the chief source of renewable water supply for humans and freshwater ecosystems 2,3. We use river networks to redistribute the distinctive impacts of stressors on human water security and biodiversity along a continuum from head-waters to ocean, capturing spatial legacy effects ignored by earlier studies. Our framework incorporates all major classes of anthro-pogenic drivers of stress and enables an assessment of their aggregate impact under often divergent value systems for biodiversity and human water security. Enhancing the spatial resolution by orders-of-magnitude over previous studies (using 309 latitude/longitude grids) allows us to more rigorously test previous assertions on the state of the world's rivers and to identify key sources of threat at sub-national spatial scales that are useful for environmental management. Finally, we make the first spatial assessment of the benefits accrued from technological investments aimed at reducing threats to human water security , revealing previously unrecognized, global-scale consequences of local water management practices that are used extensively worldwide. Global patterns of incident threat Using a global geospatial framework 22 , we merged a broad suite of individual stressors to produce two cumulative incident threat indices, one for human water security and one for biodiversity. The resulting
Time for decisive actions to protect freshwater ecosystems from global changes
Knowledge & Management of Aquatic Ecosystems
Freshwater ecosystems and their biodiversity provide fundamental services to humans such as nutritional resources production, water provisioning, water purification, recreation, and more globally climate regulation. Anthropogenic impacts on freshwater ecosystems and their biodiversity are already strong and will most probably increase in the near future. Anthropogenic drivers are widely known and include in particular, climate change, habitat shrinking and/or modification due to land-use (e.g. water abstraction for human and agricultural consumption, urbanization), habitat fragmentation and homogenization in stream flow dynamics due to the damming of rivers, introduction of non-native species, dumping of nutrient or organic loadings increasing eutrophication processes, and biodiversity over-exploitation. Here, I review the current and future effects of these anthropogenic drivers on freshwater ecosystems and their biodiversity and provide some few examples of existing solutions, eit...
Entering an Era of Water Scarcity: The Challenges Ahead
Ecological Applications, 2000
Fresh water is a renewable resource, but it is also finite. Around the world, there are now numerous signs that human water use exceeds sustainable levels. Groundwater depletion, low or nonexistent river flows, and worsening pollution levels are among the more obvious indicators of water stress. In many areas, extracting more water for human uses jeopardizes the health of vital aquatic ecosystems. Satisfying the increased demands for food, water, and material goods of a growing global population while at the same time protecting the ecological services provided by natural water ecosystems requires new approaches to using and managing fresh water. In this article, I propose a global effort (1) to ensure that freshwater ecosystems receive the quantity, quality, and timing of flows needed for them to perform their ecological functions and (2) to work toward a goal of doubling water productivity. Meeting these challenges will require policies that promote rather than discourage water efficiency, as well as new partnerships that cross disciplinary and professional boundaries.
Critical Reviews in Environmental Science and Technology, 2019
Global freshwater resources have faced critical water security challenges during the 21st century in the world's river basins. Shortages of water have impaired economic development by disrupting regimes of river flows, ecosystem functioning and food security. Excessive surface and groundwater withdrawals have almost reached the threshold. The current withdrawals of total water (4700 km 3 Áy À1) suggest the imbalance of water use and renewal rates in the world's river basins. The water security issues are further intensified by phosphate and nitrate pollution from land use and climate change. Today, about 400 million people worldwide experience extreme shortages of water for daily use. Limited availability of water which needs to meet the basic needs of hygiene and sanitation for consumption and other uses has increased competition among users. While the society demands more water-intensive goods and services, the ecosystems are however left behind, consequently leading to increased conflicts and insecurity. Equitable water allocation for people and nature is becoming increasingly urgent. However, understanding the complex interactions between the society and nature in the world's river basins is limited. This paper aims to unravel some key strategies that enhance future water security through the advancement of science, knowledge and technologies in the world's river basins.