Mike Acreman

UK Centre for Ecology & Hydrology | CEH

There is increasing global interest in employing nature-based solutions, such as reforestation and wetland restoration, to help reduce water risks to economies and society, including water pollution, floods, droughts and water scarcity, that are likely to become worse under future climates. Nature-based solutions for adaptation should be designed t...

REPORT OF THE WORK OF THE EXPERT GROUP ON MAINTAINING THE ABILITY OF BIODIVERSITY TO CONTINUE TO SUPPORT THE WATER CYCLE The tenth meeting of the Conference of the Parties to the Convention on Biological Diversity, in decision X/28 paragraph 39, recognized the good synergies between the Convention on Biological Diversity and the Ramsar Convention...

As climate change erodes current levels of flood protection in the UK and government investment in ‘hard’ flood risk management (hFRM) is rationed by cost-benefit ratios, the option for many communities at-risk is to implement local ‘soft’ FRM (sFRM). The frequency of widespread flooding generates an added urgency to understand how to support sFRM....

1.Temporary streams are dynamic ecosystems in which mosaics of flowing, ponded and dry habitats support high biodiversity of both aquatic and terrestrial species. Species interact within habitats to perform or facilitate processes that vary in response to changing habitat availability. A natural capital approach recognizes that, through such proces...

The Demonstration Test Catchment (DTC) project was commissioned in 2009 through Defra’s Agriculture and Water Quality team to test the hypothesis that ‘it is possible to cost-effectively reduce the impact of agricultural diffuse water pollution on ecological function while maintaining food security through the implementation of multiple on-farm mit...

Sand mining (used here as a generic term that includes mining of any riverine aggregates regardless of particle size) is a global activity that is receiving increasing media attention due to perceived negative environmental and social impacts. As calls grow for stronger regulation of mining, there is a need to understand the scientific evidence to...

Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one third of all vertebrate species. This biodiversity is declining dramatically: globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine...

River impoundment constitutes one of the most important anthropogenic impacts on the World’s rivers. An increasing number of studies have tried to quantify the effects of river impoundment on riverine ecosystems over the past two decades, often focusing on the effects of individual large reservoirs. This study is one of the first to use a large-sca...

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River impoundment by the construction of dams potentially modifies a wide range of abiotic and biotic factors in lotic ecosystems and is considered one of the most significant anthropogenic impacts on rivers globally. The past two decades have witnessed a growing body of research centred on quantifying the effects of river impoundment, with a focus...

This chapter highlights opportunities and challenges associated with integrated management of wetlands at the catchment and landscape scale. It discusses the fragmented nature of many catchments, and the low priority given to wetlands, in spite of their important ecological functions and valuable ecosystem services. By highlighting the need for hol...

This new report Joining the Dots: Global Challenges and the Valuing Nature Agenda from the Valuing Nature Programme provides a review of published research which elaborates synergies between the Valuing Nature Network and Global Challenges Research agendas. The report was written by a multidisciplinary team led by Valuing Nature’s Rob Fish (Univer...

River regulation by impoundment is considered one of the most significant and extensive anthropogenic impacts on riverine ecosystems globally. There is a growing body of research centred on quantifying the effects of impoundment, with a focus on the effects of individual large dams on downstream aquatic ecosystems. This study undertakes a compariso...

A decade ago, scientists and practitioners working in environmental water management crystallized the progress and direction of environmental flows science, practice, and policy in The Brisbane Declaration and Global Action Agenda (2007), during the 10th International Riversymposium and International Environmental Flows Conference held in Brisbane,...

A decade ago, scientists and practitioners working in environmental water management crystallized the progress and direction of environmental flows science, practice, and policy in The Brisbane Declaration and Global Action Agenda (2007), during the 10th International Riversymposium and International Environmental Flows Conference held in Brisbane,...

River regulation by dam impoundment is considered one of the most significant and extensive anthropogenic impacts on riverine ecosystems globally. There is a growing body of research centred on quantifying the effects of impoundment, with a focus on the effects of individual large dams on downstream aquatic ecosystems. This study undertakes a compa...

You can download the full report from here https://unesdoc.unesco.org/ark:/48223/pf0000261424

Significant progress in environmental flow management has occurred in recent years due to several factors. These include governments committing to environmental flow programs, significant progress in scientific understanding, and environmental flow assessment methods that are cognizant of stakeholder participation and co-design. However, there rema...

Water enters the terrestrial phase of the water cycle when precipitation exceeds evapotranspiration at the land surface. Downstream drainage of this water via surface and subsurface flow paths including transient storage in snowpack, soils, aquifers, and lakes combine to produce the water regimes of freshwater ecosystems. Humans have altered these...

Establishing a shared and defined vision is a critical initial step in managing river resources and implementing environmental water regimes. We argue that the vision statement is best obtained through the stakeholder engagement processes and identification of ecosystem services, set within the context of wider constraints and national priorities,...

Environmental water management is inherently a multidisciplinary endeavor, but until now there has been no single book that engages experts across all relevant areas of practice and scholarship. This book reflects the growing maturity of environmental water management as a cohesive and specialized field, which finally makes it possible to address t...

Although there has been significant progress in environmental water management across the globe, a number of challenges remain in the establishment and delivery of environmental water regimes on the ground—the implementation challenge. This final chapter focuses on the directions to achieve successful implementation of environmental water policies...

This chapter considers the historical evolution of river management objectives that have led to increased interest in maintaining or restoring environmental water flows. It contrasts the differences in cultural history in the United Kingdom, India, Australia, and Southeast Asia that have led to new requirements for environmental water. In the Unite...

The value of natural capital and ecosystem services (ESs) is widely acknowledged, but the application of the concept to environmental water is still in its infancy. This chapter argues for the need to adopt the natural capital and ESs concept and to underpin environmental flows assessments. It also highlights the numerous challenges that lie ahead...

The value of natural capital and ecosystem services is widely acknowledged but the application of the concept to environmental flows is still in its infancy. This chapter argues for the need to adopt the natural capital and ecosystem services concept and to underpin environmental flow assessments. It also highlights the numerous challenges that lie...

Water for the Environment: From Policy and Science to Implementation and Management provides a holistic view of environmental water management, offering clear links across disciplines that allow water managers to face mounting challenges. The book highlights current challenges and potential solutions, helping define the future direction for environ...

Executive Summary The effect of trees on flooding is much debated. In the aftermath of widespread flooding in Cumbria during December 2015 much attention focussed on whether natural solutions, in particular tree planting in upstream catchments, can have a role in reducing flood risk. Despite multiple literature reviews investigating links between l...

River impoundment by the construction of dams and creation of reservoirs is considered one of the most significant and spatially extensive anthropogenic impacts on river ecosystems globally. It has the potential to change and modify a range of abiotic and biotic factors, including channel morphology upstream and downstream of the structure, dischar...

China currently faces a water resource sustainability problem which is likely to worsen into the future. The Chinese government is attempting to address this problem through legislative action, but faces severe challenges in delivering its high ambitions. The key challenges revolve around the need to balance water availability with the need to feed...

Flooding is a very costly natural hazard in the UK and is expected to increase further under future climate change scenarios. Flood defences are commonly deployed to protect communities and property from flooding, but in recent years flood management policy has looked towards solutions that seek to mitigate flood risk at flood-prone sites through t...

Rivers provide water for irrigation, domestic supply, power generation and industry as well as a range of other ecosystem services and intrinsic and biodiversity values. Managing rivers to provide multiple benefits is therefore foundational to water security and other policy priorities. Because river flow is often insufficient to meet all needs ful...

The hydrological regime is a significant driver of fish population dynamics in rivers, but there is a dearth of information regarding the mechanisms behind its effects on temperate species, especially non-salmonids. This study investigated the effects of periodic and episodic flow pulses on 0+ fish biomass in a constrained lowland river. De-seasona...

Climate change and human use of water abstracted from rivers and groundwater are projected to alter river flow regimes worldwide in coming decades. Consequently, community structure in many rivers is expected to change because river flow is fundamental in determining conditions required by organisms, and processes on which they depend. Future flows...

Floods and droughts, two opposite natural components of streamflow regimes, are known to regulate population size and species diversity. Quantifiable measures of these disturbances and their subsequent ecological responses are needed to synthesise the knowledge on flow-ecosystem relationships. This study for the first time combines the systematic r...

Climate change will impact fluvial ecosystems through changes in the flow regime. Physical habitat is an established measure of a river's ecological status when assessing changes to flow. Yet, it requires extensive datasets, is site specific and does not account for dynamic processes; shortcomings that the use of hydrological / hydraulic models may...

Temperature and relative humidity measurements were made within and outside a lowland fen in eastern England during 2009 and 2010. Summer temperatures were found to be on average 0.24°C lower within the fen than outside, whilst summer vapour pressures were found to be on average 0.074 kPa higher within the fen. In contrast, winter temperatures were...

The term environmental flows emphasises the importance of water for the natural environment. For wetland ecosystems, a critical factor is the depth of water on the surface or the level of the water table in the ground. In the UK, scientists have produced quantitative guidelines on the water level requirements of wetland plant communities (according...

The term environmental flows relates to the trade-off between keeping water in a wetland system to meet ecosystem requirements and services to dependent people (such as food, recreation, and cultural identity) versus realizing the direct benefits of removing the water for drinking, growing food, and supporting industry. It describes the quantity, q...

The goal of the DrIVER (Drought Impacts: Vulnerability thresholds in monitoring and Early-warning Research) research project is to understand the links between natural (hydro-meteorological) drought and ecological response and socio-economic impacts to aid in developing enhanced drought early warning systems (DEWS). Three stakeholder workshops were...

The term environmental flows has become widely used to define the hydrological regime required to sustain freshwater and estuarine ecosystems and the human livelihoods and well‐being that depend on them. A large range of frameworks and methods has been developed to assess environmental flow needs and many authors have identified subtleties in the a...

Drought indicators are proliferating, but with little consideration of which are most meaningful for describing drought impacts. A number of recent reviews compare different drought indicators, but none assess which indicators are actually used in the many operational drought monitoring and early warning efforts, why they were selected, or whether...

The Millennium Drought taught Australians many lessons about living under extremely dry conditions – not just about how to conserve water, but also about human suffering. In a drought, farmers find it more difficult to make an income, leading to mental health problems and raising the rate of male suicides. In the city, the impact is felt through wa...

In his Farewell Editorial, Z.W. (Zbyszek) Kundzewicz (2015) provides a fascinating read, useful for older and younger hydrologists alike. It covers the history of Hydrological Sciences Journal (HSJ), official organ of the International Association of Hydrological Sciences (IAHS), not only during his long-lasting (18 years) service as Editor, but al...

Projected changes in climate are likely to substantially impact wetland hydrological conditions that will in turn have implications for wetland ecology. Assessing ecohydrological impacts of climate change requires models that can accurately simulate water levels at the fine-scale resolution to which species and communities respond. Hydrological con...

Effects of climate change on the habitat availability of brown trout were predicted using a 1D MIKE 11 hydraulic model. Flows were simulated along a 600 m reach of the River Lambourn, Boxford, UK. In-channel macrophyte growth exerts an acute effect on water levels, incorporated into the model by manipulating channel bed roughness (Manning's n). An...

In natural environments, the transformation of wetlands into terrestrial habitats is balanced by the appearance of new wetlands. Nowadays, such widespread natural processes are constrained by agriculture, urbanisation and other land use management. Therefore interventions are required to maintain many wetland types and their overall character and d...

The first river flow management for ecosystems focused on the concept of a minimum flow for diluting polluted discharges, based on the notion that as long as the flow is maintained at or above a critical minimum, the river ecosystem will be conserved. CEH have made major contributions to this research in ecohydrology particularly in river, wetland...

Understanding of hydrological processes in wetlands may be complicated by management practices and complex groundwater/surface-water interactions. This is especially true for wetlands underlain by permeable geology, such as chalk. In this study, the physically based, distributed model MIKE SHE is used to simulate hydrological processes at the CEH R...

Throughout the world, historic drainage of wetlands has resulted in a reduction in the area of wet habitat and corresponding loss of wetland plant and animal species. In an attempt to reverse this trend, water level management in some drained areas is trying to replicate a more natural 'undrained' state. The resulting hydrological regime is likely...

Monitoring and Early-Warning (M&EW) systems are crucial for reducing societal vulnerability to drought. While there are a range of extant M&EW systems globally , such systems are typically based on physical (hydro-climatic) indicators, and they have rarely been linked to societal or environmental impacts. This is the starting point for the internat...

Wetlands in agricultural landscapes offer a number of benefits to the landscape function in which they are set, reducing nutrient runoff, providing additional habitat mosaics and offering various ecosystem services. They require careful planning and maintenance in order to perform their optimum design function over a prolonged period of time. They...

The term ?environmental flows? describes the quantities, quality, and patterns of water flows required to sustain freshwater and estuarine ecosystems and the ecosystem services they provide. Environmental flows may be achieved in a number of different ways, most of which are based on either (1) limiting alterations from the natural flow baseline to...

In many of the world’s river basins, the water resources are over-allocated and/or highly modified, access to good quality water is limited or competitive and aquatic ecosystems are degraded. The decline in aquatic ecosystems can impact on human well-being by reducing the ecosystem services provided by healthy rivers, wetlands and floodplains. Basi...

Abstract The aim of this article is to assess the impact of four scenarios combining possible changes in climate, atmospheric carbon dioxide, land use and water use by 2050, on the specific set of ecologically relevant flow regime indicators that define environmental flow requirements in a semi-natural river basin in Poland. This aim is presented t...

Fens represent a large array of ecosystem services, including the highest biodiversity found among wetlands, hydrological services, water purification and carbon sequestration. Land-use change and drainage has severely damaged or annihilated these services in many parts of North America and Europe; restoration plans are urgently needed at the lands...

Development of environmental flow standards at the regional scale has been proposed as a means to manage the influence of hydrological alterations on riverine ecosystems in view of the rapid pace of global water resources management. Flow regime classification forms a critical part in such environmental flow assessments. We present a national-scale...

The term "environmental flows" is now widely used to reflect the hydrological regime required to sustain freshwater and estuarine ecosystems, and the human livelihoods and well-being that depend on them. The definition suggests a central role for ecohydrological science to help determine a required flow regime for a target ecosystem condition. Inde...

A MIKE SHE model of the Mekong, calibrated and validated for 12 gauging stations, is used to simulate climate change scenarios associated with a 2°C increase in global mean temperature projected by seven general circulation models (GCMs). Impacts of each scenario on the river ecosystem and, hence, uncertainty associated with different GCMs are asse...

Projection of future changes in river flow regimes and their impact on river ecosystem health is a major research challenge. This paper assesses the implications of projected future shifts in river flows on in-stream and riparian ecosystems at the pan-European scale by developing a new methodology to quantify ecological risk due to flow alteration...

Environmental flows—the quantity of water required to maintain a river ecosystem in its desired state—are of particular importance in areas of high natural value. Water-dependent ecosystems are exposed to the risk of climate change through altered precipitation and evaporation. Rivers in the Narew basin in northeastern Poland are known for their va...

It is widely recognised that wetlands play an important role in the hydrological cycle, influencing groundwater recharge, low flows, evaporation and floods. This has led to policies being formulated world-wide to conserve and manage wetlands to deliver these key services, especially flood risk reduction. Generic statements have often been published...

Wetlands have been the focus of conflicts in societal priorities throughout human history, with competing demands for water and land use delivering a range of ecosystem services but contributing to severe degradation and loss. Conservation of wetlands is a relatively recent priority, and it has seen more recent shifts from protection of remaining w...

In this chapter the authors argue that the inclusion of higher order (turbulent) properties of the flow constitutes a more complete and ecologically relevant characterisation of the hydraulic environment that biota are exposed to than standard ecohydraulic variables alone. After outlining the theory, structure and measurement of turbulent flow in o...