̽��ֱ�� of Cambridge - Iris Moller

Sea Change

sc604 — Fri, 22 Mar 2019 09:13:26 +0000

̽��ֱ��coast is an intrinsic part of British identity – and perhaps nowhere is it more at risk than in the East of England. Cambridge researchers are working with communities and organisations across the region to manage the coast for the future, by working with nature rather than against it.

Salt marsh plants key to reducing coastal erosion and flooding

sc604 — Thu, 02 Oct 2014 10:07:00 +0000

̽��ֱ��effectiveness of salt marshes – wetlands which are flooded and drained by tides – in protecting coastal areas in times of severe weather has been quantified in a study by researchers from the ̽��ֱ�� of Cambridge.

In the largest laboratory experiment ever constructed to investigate this phenomenon, the researchers have shown that over a distance of 40 metres, the salt marsh reduced the height of large waves in deep water by 18%, making them an effective tool for reducing the risk of coastal erosion and flooding. Sixty percent of this reduction is due to the presence of marsh plants alone. ̽��ֱ��results are published in the journal Nature Geoscience.

One of the most noticeable effects of climate change is the increasing frequency and severity of storms, such as the series of storms which battered parts of south west England last winter. As the climate continues to warm and sea levels continue to rise, the effects of these storms could be devastating, putting these and other coastal communities worldwide at risk.

While the important role of salt marshes in protecting against coastal erosion is well-known, their effectiveness in mitigating the effects of extreme weather, when water levels are at their maximum and waves are at their highest, had not been understood or definitively quantified.

Recreating a salt marsh in a large wave tank and subjecting it to realistic storm conditions, the researchers found that it significantly ‘buffered’ the effects of the waves. Similar to wind blowing through a forest, the plants reduce the energy of the water as it flows through and around them. Even when the waves flattened and broke the marsh’s vegetation, the soil surface beneath remained stable and resistant to surface erosion.

Salt marshes are found throughout the world, particularly at middle to high latitudes. In addition to their role in protecting against coastal erosion and reducing flooding, they also act as nurseries and refuges for many species of marine animals, and protect water quality by filtering runoff.

Given increased rates of global sea level rise, there are concerns about losing salt marsh on many coasts, particularly where there is insufficient sediment and space to allow marshes to build upwards and landwards.

“While we have long known that salt marshes and other natural defences such as sand dunes or mudflats can help protect our coastlines, a lack of data on their effectiveness in extreme conditions has meant that they often are not included in flood risk assessments,” said Dr Iris Möller of Cambridge’s Department of Geography (Cambridge Coastal Research Unit), who led the research. “But we’ve shown that even in extreme conditions, salt marshes are a vital defence for our coastlines and protect against more frequent storms.”

̽��ֱ��researchers used large sections of salt marsh, cut from a natural marsh in northwestern Germany. ̽��ֱ��team then rebuilt the marsh in one of the world’s largest wave tanks, located in Hannover, and subjected it to water depths and types of waves that are typical in storm surge conditions. Even after the waves flattened the plants, the marsh was still an effective barrier against erosion, demonstrating the importance of natural flood defences alongside manufactured defences such as flood walls.

̽��ֱ��flooding which hit south west England last winter was the worst in nearly 20 years. A series of 12 major storms between December and February caused huge waves, strong winds and hide tides to pummel large parts of Cornwall, Devon and the southwest, causing millions of pounds worth of damage. Many homes and businesses were flooded multiple times, and major flooding in the Somerset Levels forced many families to evacuate their homes and many farmers to evacuate their livestock.

As part of the government’s attempts to mitigate the effects of future storms, salt marshes have been re-created in several locations around the UK coast: a large new salt marsh on the Somerset’s Steart peninsula was recently completed, and several more are planned for locations throughout the UK.

̽��ֱ��research was supported by the European Community’s 7th Framework Programme and a grant from ̽��ֱ��Isaac Newton Trust, Trinity College, Cambridge.

̽��ֱ��researchers are blogging about their work at thesaltmarshexperiment.wordpress.com.

Study finds that natural flood defences such as salt marshes can reduce the height of damaging waves in storm surge conditions by close to 20%.

Even in extreme conditions, salt marshes are a vital defence for our coastlines

Iris Möller

James Tempest

Storm on a rising tide, Orplands, Essex

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Putting a value on what nature does for us

sc604 — Thu, 11 Sep 2014 13:00:00 +0000

A new online resource, developed by researchers at the ̽��ֱ�� of Cambridge in collaboration with other organisations based in Cambridge, helps those in both the public and private sector see how changes to an ecosystem can affect its value, in order to make more informed decisions about how the natural environment should be developed.

̽��ֱ��Toolkit for Ecosystem Service Site-based Assessment (TESSA) was launched online this week to coincide with the 7th Annual Ecosystem Services Partnership Conference in Costa Rica, and allows users to make a direct comparison of the value that an ecosystem can provide to a community in different states, by providing access to state of the art information about their financial value.

Ecosystems provide us with an extensive range of benefits for free, often described as ‘ecosystem services’. These benefits include the provision of food and clean water, erosion control and carbon storage. A reduction or loss of these services can have severe economic, social and environmental impacts. However, methods for obtaining such data are frequently too expensive, or too technically demanding, to be of practical value.

TESSA has been developed by a consortium of experts from six institutions, including staff at the Departments of Geography and Zoology. It allows non-experts to derive reasonable estimates that an individual location provides to society, both locally and globally. TESSA provides guidance and methods to value the services provided by an ecosystem at a specific location compared to the likely provision of such services under different management decisions. This allows the consequences of alternative management decisions to be assessed.

“If a mangrove forest was cut down and turned into a shrimp farm, or a forest was converted to grassland - what is the value of each of those habitats and what is the impact of such a change on different people? We can now provide a quantitative way of determining the value of the many ways in which an ecosystem works for us,” said Dr Iris Möller of the Department of Geography and Fitzwilliam College, one of the leaders of the project. “A thirsty forest may help prevent flooding in an area, but it can also contribute to drought. This tool allows us to determine what would happen to that water if the forest were to be cut down.”

TESSA addresses the gap in valuation tools available for non-expert use at the site level and to date has been used at 24 sites spread across five continents. Most users have been conservation practitioners, although the methods are applicable to a wide range of users, including natural resource managers, land-use planners, development organisations and the private sector.

“We hope that by making TESSA more intuitive to use, and available both on- and offline, many more people will be able to assess the ecosystem service values of sites and how they might change under different land use decisions,” says Jenny Merriman, BirdLife’s Ecosystem Services Officer and TESSA Coordinator.

“This information is critical for informing decision-making at the local level and when scaled up, can demonstrate the social and environmental consequences of our actions,” said Möller.

Building on previous funding from other sources, including the Cambridge Conservation Initiative (CCI), the development of the interactive TESSA manual was funded by an ESRC Impact Acceleration Account pilot grant awarded to Cambridge ̽��ֱ��. TESSA is an evolving resource and, subject to continued funding, more content will be added in future versions.

TESSA is the result of a collaboration between the ̽��ֱ�� of Cambridge, Anglia Ruskin ̽��ֱ��, BirdLife International, Tropical Biology Association, RSPB, and UNEP-WCMC.

Interactive online tool allows the value of an ecosystem to be calculated, and allows users to determine how altering a habitat can affect its economic, social and environmental worth.

We can now provide a quantitative way of determining the value of the many ways in which an ecosystem works for us

Iris Möller

Phil's 1stPix via flickr

West Summerland Key Mangrove Ecosystem, Florida Keys

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Climate change: can nature help us?

Anonymous — Wed, 08 May 2013 11:05:19 +0000

Flooding, landslides, crop failure, water shortages. Across the globe, the frequency with which humans are suffering the ill effects of climatic variability and extreme weather events is on the increase. Can natural environments be used effectively to help people adapt to the effects of climate change? ̽��ֱ��first systematic review of this question – facilitated by the Cambridge Conservation Initiative (CCI) Collaborative Fund for Conservation – finds much evidence of their effectiveness.

" ̽��ֱ��delays in international agreements on ways to reduce global greenhouse gas emissions mean that planning to counter the impacts of climate change is a necessity,” said Robert Munroe, Climate Change Officer at BirdLife International. “Governments of all countries should be making plans to protect us against these impacts.”

One adaptation option is to invest in costly, large-scale structures such as sea walls, irrigation systems and dams. But while their short-term impact is clear, these solutions lead to ever-increasing maintenance costs and often have negative impacts on local ecosystems and biodiversity.

“International policy makers are having to think about the different approaches they could take, but the problem is that they don’t have enough information to make informed decisions,” said Munroe.

“Hard-engineered sea walls have a limited life span, and we know that they change wave and tidal currents, often to the detriment of saltmarshes or mangroves that act as a natural buffer to storm surges and coastal erosion. Do we really want to lose these buffers and face increasing costs of sea wall maintenance?” asked Dr Iris Möller, Deputy Director of the Cambridge Coastal Research Unit in the Department of Geography.

“There’s anecdotal evidence from events like the 2004 Indian Ocean tsunami that villages surrounded by mangroves were significantly less affected by the tsunami than more exposed areas,” she added. ̽��ֱ��mangroves may have saved thousands of lives and properties by absorbing a large proportion of the energy in the waves.

But local anecdotal evidence is not enough to provide a reliable measurement of the effectiveness of an approach. Now a review has been completed of the effectiveness of natural approaches to buffering the effects of climate change. Termed Ecosystem-based approaches for Adaptation (EbA), this relatively new concept incorporates approaches that have been used for a long time to address climatic variability, but not necessarily in the context of adaptation to climate change.

“We wanted to understand what the research evidence tells us, in terms of the relative importance of ecosystems as opposed to hard-engineering solutions to the same problem,” said Dr Bhaskar Vira in the Department of Geography. Vira, Möller, Dr Tom Spencer (Director of the Cambridge Coastal Research Unit) and Dr Andreas Kontoleon (Department of Land Economy) worked with climate change policy expert Munroe at BirdLife and climate change expert Dr Nathalie Doswald at the United Nations Environment Programme World Conservation Monitoring Centre, as well as with the International Institute for Environment and Development in London. They looked at published studies from around the world in which a wide range of EbA had been assessed. ̽��ֱ��step-by-step detail of their systematic review method was published in Experimental Evidence in 2012, which will enable it to be replicated for consistency in future studies.

“ ̽��ֱ��systematic review is very specific: we sifted out the most relevant published studies and compiled evidence from them on the different interventions being used and how effective they have been,” said Vira. ̽��ֱ��team found that activities related to EbA have been used across the globe to address a broad range of climatic hazards and impacts.

Interventions include the sustainable management of wetlands and floodplains to act as floodwater reservoirs and provide important water stores for times of drought, and the conservation and restoration of forests and natural vegetation to stabilise slopes and regulate water flows, preventing flash floods and landslides due to increased rainfall. Most of the approaches were reported by the studies to be effective in reducing human vulnerability to the effects of climate change, climatic variability or natural hazards.

“ ̽��ֱ��results are providing general guidance on the circumstances in which an EbA may be useful,” said Vira. “There are cases where it isn’t necessarily going to be helpful – if you live in Gloucestershire and you’re about to get flooded, you can’t start planting trees, you have to use sandbags. These interventions take time, and there are limitations to their effectiveness.”

“It’s important to work towards fully informed decision-making between alternative adaptation approaches,” said Munroe. “Large-scale infrastructural solutions may tend to be pursued because the financial costs are clear and their short-term effectiveness at buffering hazards has been tested by engineers. But by constraining natural ecological cycles, they may increase social vulnerability in the medium to long term. We found some discussions on the comparison between ecosystem-based and other kinds of approaches to adaptation, which are valuable for policy makers.”

“We also realised there are some real knowledge gaps,” added Möller. “We need information on the costs as well as the benefits, and on whether monitoring systems have been put in place to assess the long-term effectiveness of these approaches. With respect to ecosystems as coastal protection, for example, we need to know exactly how much energy mangroves and marshes absorb and what we can do to maximise and maintain the effect.”

̽��ֱ��project collaborators recognise that the divide between scientific research and policy making must be bridged if governments are to make the best decisions for long-term adaptation to climate change. “Our partnership with NGO colleagues meant the project has both academic rigour and a built-in pathway to impact,” said Vira. ̽��ֱ��Collaborative Fund for Conservation, which was established with the generous support of the Arcadia Fund, was set up explicitly to foster these innovative partnerships.

̽��ֱ��team’s collective range of contacts has enabled them to disseminate their results and recommendations. Their presentations at the United Nations Climate Change Conference in Durban in December 2012, and the distribution of briefing papers and guidance documents, have drawn the attention of decision-makers at the highest levels to the possibilities of ecosystem-based approaches.

“A technical workshop on EbA, likely to involve 70 countries, was recently convened by the Climate Change Convention,” said Munroe. “Our work contributed to the momentum that resulted in this decision. It’s really exciting as it’s the first time the Convention has met to discuss this approach.”

“EbA is an important tool in the adaptation toolkit, which has often been ignored because the evidence base had not been made clear,” said Munroe. “Employing it alongside other adaptation options will result in much more sustainable responses to the effects of climate change in both developed and developing countries.”

Hard-engineered sea walls have a limited life span. Could saltmarshes and mangroves offer a different approach to buffering against storm surges and coastal erosion?

Do we really want to lose these buffers and face increasing costs of sea wall maintenance?

Iris Moller

Saltmarshes starting to be inundated by the tide at Abbots Hall, Cumbria, UK

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After the flood: harnessing the power of mud

hps25 — Thu, 31 Jan 2013 12:46:44 +0000

Sixty years ago tonight, a storm surge in the North Sea caused catastrophic flooding on the coast of eastern England. ̽��ֱ��‘big flood’ of 1953 inundated more than 65,000 hectares of land, damaged 24,000 houses and around 200 important industrial premises, resulting in 307 deaths in the immediate flooding phase.

In the aftermath, sea defences were developed and major protection schemes were implemented – the eventual construction of the Thames Barrier being the most conspicuous example. Warning services and emergency responses to flooding became coordinated at a national level, something which hadn’t existed in 1953.

But many of these reinforcements will reach the end of their design life in the next decade. Experts analysing storm surge height and wave activity believe the flood to be a once every 50 year event – it will happen again, they say, it is only a question of when.

Environmental changes and possible sea-level rises hadn’t been properly anticipated when protection schemes commenced, and UK coastal populations have risen by up to 90% in certain areas since 1953 – many designated as high flood risk.

“Such contexts call for more research into complexities of storm surge dynamics, strengthening of coastal planning policy and a more nuanced approach to coastal engineering,” said Dr Tom Spencer, Director of the Cambridge Coastal Research Unit (CCRU) from the Department of Geography.

̽��ֱ��CCRU are currently researching the effectiveness of the natural flood defences offered by coastal ecosystems such as salt marshes and mud flats. They suggest a ‘hybrid engineering’ approach, combining sea walls with natural ecosystems. Such ecosystems not only provide flood protection but store carbon, filter pollutants and increase biodiversity. Over recent years, these important habitats that have become “squeezed out” by rising sea levels and hard sea defences.

̽��ֱ��research is part of a six year programme involving 14 other institutions, funded by the Natural Environment Research Council. ̽��ֱ��teams are focusing on the marshlands of the Essex coast and Morecambe Bay.

“We already know that some of the Essex marshes regularly reduce the energy of waves by up to 90% over a distance of 80 metres or so,” said Dr Iris Möller, Lecturer in Physical Geography at Fitzwilliam College and co-investigator on the project.

“Hard defences are expensive and doomed to fail or incur ever-increasing costs. A key priority is the need to restore a natural coastal ‘buffer’ zone, free from human occupation and compatible with the ‘inbuilt’ ability of the coast to respond dynamically to environmental change – such as sea level rise or more frequent storms.”

̽��ֱ��researchers say they now have the technology to accurately measure wave depth and energy across marshes and mud flats, providing engineers and policy makers with the information they need to show the effectiveness of ecosystem-inclusive sea defence systems.

By installing a total of 42 wave recording devices at marshes in Essex and Morecambe Bay, with measurements controlled by solar-powered data logging systems, the team can track wave level and pressure variations as water moves across mud and vegetation. This information is continuously streamed back to Cambridge via mobile phone networks.

̽��ֱ��team are finding that the mud and plants of the marshes naturally dissipate the ferocity of waves from storms, whereas just seawalls can alter the shape of the coast artificially, causing greater erosion through energy redistribution.

̽��ֱ��Cambridge wave research is part of the Coastal Biodiversity and Ecosystem Services Sustainability project, looking at the range of benefits natural ecosystems can provide – from carbon stores to pollution sinks as well as wave buffers – and how they can integrate with traditional flooding engineering.

“It is important to understand the value of varied habitats that make up the landscape of the UK,” said Professor David Paterson, project leader from the ̽��ֱ�� of St. Andrews. “Coastal systems are some of the most sensitive to pressures of climate change”.

Adds Spencer: “It’s vital that we also investigate the role of ecosystems in coastal risk reduction and how, through ‘hybrid engineering’, both types of approach to coastal defence can be brought together to reduce risks and provide a long-term and robust response to the threat of catastrophic coastal flooding.”

On the 60th Anniversary of the ‘big flood’ that devastated the coastline of eastern England, new research shows that integrating ‘natural’ sea defences such as salt marshes with sea walls is a more sustainable and effective method of flood prevention.

Both types of approach to coastal defence can be brought together to reduce risks and provide a long-term and robust response to the threat of catastrophic coastal flooding.

Tom Spencer

Dr Iris Moller

Mudflat and marsh at Abbots Hall, Essex

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