Thank you for reading over the past few months and an extra special thank you for those of you that commented along the way. You raised some thought provoking questions which were interesting to think about. I hope you have enjoyed my blog!
Fans and followers of the world, it is time to say goodbye ...
"An event or occurrence that deviates beyond what is normally expected of a situation and that would be extremely difficult to predict. The event is a surprise, the event has a major effect."
This term was popularised by Nassim Nicholas Taleb, a finance professor and former Wall Street trader.
The situation is clear.
On one side we have people, their livelihoods and resources. These people have evolved over thousands of years learning to adapt in the face of adversity and peril, and cultivate resources required to advance or sustain. These people have learned how to live longer. Medical service provision and technologies have grown hyperbolically, lifestyles have changed, health economics are widespread and regenerative and anti-aging drugs have seen tremendous investment. Population growth in unprecedented, and, as documented in this blog, many of these people are living in increasingly dangerous territories. More people are living in cities, more people are living in coastal developments, and the more people are placing enormous pressures on global resources. Energy consumption, particularly fossil fuel exploitation is at unsustainable levels. Food production is strained and water resources are drying up. Yet, this pressure is fuelling a population of over 7 billion people. Will this unprecedented growth of humans, and their control over the Earth system become under increasing regulation?
On the other side of this delicate equilibrium are events or measures that keep this population and their business in check. This blog has discussed 'natural' hazards. As we the human race continue to modify the climate system we risk grappling with natures forces at levels not seen before. Hazards are changing, and so is the vulnerability of humans. We have managed to increase the risk of both our position and the hazard. Tropical cyclones are becoming stronger, extratropical cyclones more unpredictable, flooding more intense and irregular, earthquakes have been triggered by man, decertification and drought cripples resources, weather systems are altered. Whilst high frequency events are less able to penetrate the human advances and defences, the 'tail events' or 'Black Swann' events have the power and destructive capabilities to obliterate our battle against risk and vulnerability. Consider the implications a category one hurricane had on NYC last year. A Category 4 storm is predicted to cause over 500 billion dollars of loss. Consider the implications of predicted sea level rise on Amsterdam, an eruption of Mount Rainer on Seattle, and earthquakes in Tokyo or Istanbul. Megaclusters of population are becoming an increasingly large ticking time bomb for Black Swan events to wipe them off the map. Perils not considered in this blog include global pandemic influenza, mass casualty terrorism or pandemic disease. All of these have the potential to cause mass destruction of population in an increasingly interconnected world.
People have evolved, hazards have evolved and risk has evolved. Never has the world and its ill-prepared population been been more susceptible to an unexpected Black Swan event.
The main idea in Taleb's book is not to attempt to predict black swan events, but to build robustness against negative ones that occur and be able to exploit positive ones. Will societally take note of the warning signs. Will REAL long term action be take in lieu of Hurricane Sandy and Katrina, 9/11, SARS, AIDS, Tohoku, the Indian Ocean Tsunami, the China floods, and Haiti. At the moment, the evidence is scarce.
There have been multiple reactions to the recent storms that have devastated parts of the UK. This has triggered politicians and civilians point fingers at the anthropogenic climate change. For example, on Wednesday 8th of February Prime Minister David Cameron said he "very much" suspected that an increase in abnormal weather events was linked to climate change.
"No attribution study has been done, so you can't make a definitive statement about how more or less likely the recent flooding has become because of climate change."
''There has been some observed increase in some types of extreme weather and there is some evidence, depending on which types of extreme weather you are talking about, of a link between man-made climate change and some types of extreme weather"
"You can't say definitively that an event is caused by climate change and climate change only because we have always had extreme weather.''
"But the chances of extreme weather occurring may have altered because of climate change. So it would be consistent with the picture we have seen of increasing rainfall in the UK over the past few decades."
A changing hydrological regime is of chief importance to
human societies. Unstable global hydrological cycles can influence food
production, settlement location, disease transportation, ecosystem services,
and, fundamentally, lifestyles. A shift in one direction of the continuum from
arid lands to a moist environment is perhaps one of the most striking
consequences of a changing climate. Throughout the Holocene we have seen
hydrological changes across the globe. In low latitudes there was a tendency
for low latitude regions to experience a drier system from the mid-Holocene
onwards, with a weakening of summer monsoon systems (Oldfield, 2005). Of
course, temperature plays a key role in regulating moisture regimes. There is
significant evidence from a variety of sources including pollen and
fossil-based evidence from lakes, faunal distribution, and archaeological
records that these changes even influenced the Sahara desert (deMenocal andTierney, 2012). Check out these snap shots that summarise some of the evidence
and changes observed in this region through the Holocene. The Sahara was ‘well
vegetated with widespread freshwater lakes and abundant water-loving
animals.... and extensively settled by human populations’:
At the present day environmental managers, government
advisors and scientists need to understand exactly how river systems will
respond to a changing climate. Many of the world’s major cities have been built
around river systems that will be subject to change and could threaten normal
activities associated in the region. For many people, the river is still one of
the most important natural resources for harvesting food, transportation, water
resources and many other things.
Whilst climate change may threaten shifts in the
hydrological regime, morphological alterations are just as important. A
changing climate will have implications for sedimentation, erosion and other
river processes. Macklin and Lewin (2003) present an 11.5 ka yr record of river
response to climate change for the UK. The results are based on radiocarbon
dated alluvial units up to 2002, separated by alluvial environment – channel
deposits, fills in abandoned channels, floodplain surfaces and flood basins. 14
major flood episodes spanning ~10 ka yr were identified:
Having identified these episodes, there were compared
to proxy climate record from Britain, Europe and North America:
The authors state that ‘the emerging evidence for an increase in the frequency of severe floods in major world rivers during the twentieth century is therefore entirely consistent with the Holocene fluvial sedimentary record where river systems appear to reflect global climate changes. The unusually long and complete British record also demonstrates that changes in land cover, principally the conversion of woodland to agricultural grassland, have resulted in a step change in river basin sensitivity to variations in climate. Such sensitivity might otherwise be absent from humid temperate environments. This has very important implications for assessing and mitigating the impact of increasing severe flooding. In small and medium sized river basins land use is likely to play a key role in either moderating or amplifying the climatic signal. In Britain river basin managers and planners now have the advantage of hindsight provided by the Holocene alluvial record and can hopefully avoid mistakes made by their prehistoric farming ancestors.’
Happy New Year one and all. It would be rude not to wish you all a fabulous 2014. And what better way to spend New Years day than updating my blog for my hardcore fans and followers. Without further ado, please sing-a-long to ABBA's rendition of 'Happy New Year', you know you want to.
Moving on swiftly.
As promised, I will now look at ways in which cities are acting to mitigate the impact of flooding. How? If I told you now that would be cheating. You'll just have to read if you want to find out which techniques can be used to protect and limit damage to a city and its population.
Flood impact is one of the most significant disasters in the world. The causes of floods are due to a combination of natural and human factors, from heavy rainfall to aggravation of drainage channels, from high floods to improper land use. As explored in previous posts, population increases result in more urbanisation, more impervious area and less infiltration thus greater flood peak and run-off (Tingsanchali, 2012).
As displayed in the diagram below, the urban flood Risk = Hazard x Vulnerability
There are two types of flood mitigation and prevention:
Structural flood and control measures e..g construction of dams and river dikes
Non-structural measures e.g. flood forecasting and warning, public participation, risk management
In most development countries, flood disaster management activities are handled by government and are mostly reactive responding to prevailing disaster situations. Critics suggest that this should be changed to a more proactive response to increase effectiveness of management and reduce losses of life and properties. However, this involves more effort, time, budget, equipment, facilities and human resources.
Preparedness before flood impact (e.g. warning and forecast)
Readiness upon flood arrival
Emergency responses during flood impact
Recovery and rehabilitation after flood impact
Flood management does not strive to eliminate flood hazard as flood risks cannot be entirely avoided. Thus there are many ways in which cities go about managing their flood risk. I describe some of these mitigation techniques below:
2. Modelling and forecasting are basic steps of risk management in order to mitigate flood hazards. This process includes identification of all water related hazards, analysis of hydro-meteorological data and the hydraulic simulation of floods. A number of different scenarios can then be modelled to factor in the consequences of urban floods providing information about the expected flood frequencies and magnitudes therefore highlighting those areas which are vulnerable.
3. Reduction of surface run-off is an important factor to consider when mitigating flood risk in urban areas. This can be achieved by increasing infiltration and evapo-transpiration from the catchment areas by preserving unsealed and greened spaces in the city.
4. Cleaning and maintenance of drainage is essential to ensure their operational reliability. A major cause of flooding due to heavy rainfall is the blockage of drainage facilities with rubbish. Thus in order to mitigate the flood risk, cleaning and maintenance must be in place.
5. Detaining or diverting run-off is a structural measure that may be implemented in order to mitigate urban floods due to over-bank flow. This includes polders and basins, bypass channels, dredging and widening of stream and channels, levees and embankments. Whereas tidal barriers can be used to reduce flooding due to high tides.
6. Developing workable evacuation plans is an approach that can be used to reduce the physical vulnerability of people. Evacuation shelters, supply of fresh water, food, medicine are all factors which contribute to an efficient and coherent evacuation plan.
Right. That's all for today folks. Happy New Year!
Flooding in Northern England following torrential rain over the Christmas period
In terms of flooding, average economic losses alone exceed $6 billion in the US and these losses have been rising relative to increases in population! The flooding caused by Hurricane Katrina which caused over $200 billion in losses was the most costly natural disaster in US history. Coastal cities such as Bay St Louis, Pass Christian and Waveland have increased exposure to catastrophic losses from disasters and thus were nearly obliterated. Should this mass flooding serve as reminder to densely populated coastal populations around the world of their vulnerability to natural hazards?
The UK was subject to flooding across over the Christmas period: claiming lives, causing evacuations, power cuts and chaos, the costs of being under prepared for natural hazards is huge. The Environmental Agency has released another warning stating that Britain faces another month of flood and that there is 'no end in sight' to the bad weather which has disrupted festivities and already brought misery to more than 10,000 people nationwide. The following table shows the flood warnings in place across the UK as of 30/12/2013 at 12:07.
A study by Berke et al. revealed that local governments in the US give more attention to New Urban developments in applying land use regulatory and incentive techniques, public participation initiatives and technical assistances. They have been criticised for being reluctant to anticipate future risks and giving less attention to the use of non-structural mitigation techniques and storm water BMPs. Experts have suggested that more attention needs to be placed on non-structural hazard mitigation in order to counter the building of high-density developments in flood-prone areas in cities across the globe. High-quality planning would mean that attention would be paid to issues such as hazard mitigation thus losses from flooding would be lower in communities that prepare and implement plans for urban development. However this is frequently ignored and continues to occur - a clear example of this are the huge slum developments that are increasingly vulnerable to flooding. This paper looks into the responses of slum dwellers affected by flooding in India.
Looking into the future, hazard mitigation standards such as Smart Code will play a more important role. They prioritise design features such as pedestrian orientated streets, mixed land uses as well as protection of environmentally sensitive areas given their critical mitigation services. However in order to rely on environmentally sensitive natural systems such as wetlands, sand dunes and mangroves to manage and store flood waters, they must be protected.
New urban developments are laboratories within which we can cautiously experiment with hazard mitigation and environmental protection strategies. They are a living test of how to deal with emerging hazards such as sea level rise and more intense weather events linked to global climate change.
Next time I will look at ways in which cities are acting to mitigate the impact of flooding via levees, storm surge barriers, etc. In the meantime, if you can't get enough of climate change adaptation strategies and flood risk reduction in cities be sure to check out this paper.
