The Indian state of Kerala was hit by heavy flooding. More than 350 people have died, more than one million have been evacuated in over 4,000 relief camps. Tens of thousands stranded
The crisis reminds us in good time that climate change is likely to increase the frequency and extent of severe flooding around the world. Although no single tide can be directly linked to climate change, fundamental physics confirms that a warmer world and atmosphere will contain more water, which will lead to more intense and extreme rainfall.
The monsoon season, however, usually brings heavy rains This year, Kerala has 42% more rain than expected, with more than 2,300 mm of rain in the entire region since the beginning of June and over 700 mm in August.
These are similar to Hurricane Harvey's Houston hit in August 201
Much of this water would normally be braked by trees or other natural obstacles. But over the past 40 years, Kerala has lost almost half of its forest area, covering 9,000 square km, just below the size of Greater London, while the state's urban areas continue to grow. This means that less precipitation is trapped and more water flows quickly into overflowing rivers and streams.
One of the most striking things from the videos and images that come out of the area is the brown color of the flood and the extreme damage caused by landslides. Our recent research has shown that geomorphology – the processes of erosion and deposition that characterize the Earth's surface – is sensitive to precipitation intensity, so that more frequent and extreme floods cause faster changes in our landscapes.
How "extreme" are the floods in Kerala
The floods were described by the Prime Minister of Kerala as "the worst in 100 years". Similar descriptions are often used to try to determine the magnitude of a flood, such as a "100 year flood event," although it is generally recognized that such descriptions are ineffective for communicating the flood risk. Our way of thinking about the likelihood and the risk of flooding and measuring the extent of it must urgently be updated. The 100-year flood, which has a 1% chance each year, is not perceived in public consciousness.
Another way to think about it is that a 100-year flood has occurred at a specific location near a probability of one in four within the life of a 25-year-old mortgage. A 25% chance that your home will be flooded before you pay it is much easier to allocate and more likely to lead people to consider and tackle their own individual risk.
Similarly, governments at both regional and national levels Agencies and first responders need to develop improved flood maps and update them to include insecurity. In addition, we need more effective communication and public engagement to improve flood risk competence – in the long term, this will help improve policy decisions. The British 25-year environmental plan is a step in that direction.
Most critically, we must accept that the behavior of the rivers will shift with the changing climate and changing precipitation patterns. All of our flood risk assessments are currently adopting a static, stationary system in which rivers respond in the same way as in the past. An increase in rainfall and, in particular, extreme events will cause our landscapes to adapt. Rivers and their pools are becoming more dynamic and changeable.
How quickly rivers change and how quickly we respond to drainage and flood control measures will play a significant role in our emerging flood risk. This will measure how quickly societies and their governments are accepting more resilient forms of life with water.
Floods are a challenge at the individual, local, regional and global level and will increase in the future and its impact will be more damaging. We need solutions for each of these scales to enhance individual and societal resilience – so when flooding occurs, it's not the catastrophe we're experiencing in Kerala right now.
Daniel Parsons, Professor of Process Sedimentology and Associate Dean of Research (Science and Technology), University of Hull, and Christopher Skinner, postdoctoral fellow in numerical modeling of fluvial geomorphology, University of Hull. This article was originally published in The Conversation. Read the original article. We welcome your comments at email@example.com.