Flooding: an example of human physical processes interacting

The 2005 Carlisle Floods

Carlisle is situated on the flood plain of the River Eden with three rivers meeting in the city. The catchment covers approximately 2400km2 and is home to approximately 244,000 people. The catchment is mainly rural, with only 1% classified as urban: the main urban areas are Carlisle, Penrith and Appleby.

Across the catchment, the January 2005 flooding affected 2,700 homes. In Carlisle three people died, 1,844 properties were flooded and there was significant disruption to residents, businesses and visitors. The cost of the flooding was estimated at over £400 million. The flooding followed prolonged heavy rain, and was caused by a combination of floodwater from the Rivers Eden, Pettereril and Caldew and localised flooding from sewers and road drainage.

The January 2005 flood was a major event. Rainfall was very high for the period 6 to 8 January, during which two months' worth of rainfall were released in 24 hours. However, it followed a month of high rainfall in the Carlisle area, so the ground was saturated and would no longer allow water to infiltrate, and surface run-off was excessive. The result was rapidly rising water levels in a number of rivers including the Eden.

The first warning of flooding in Carlisle by the Environment Agency was at 17:18 on 7 January and further warnings were given in the early hours of 8 January. The Agency did not predict that the Carlisle flood defences would be breached but the exceptional river flows made it hard to predict the height of the water. A feature of the event was that flooding was often initially caused by surface water flows as the local drainage networks were overwhelmed.

• 67% of the flooding resulted from rivers and watercourses
• 25% of flooding was caused by surface water
• 8% was due to flooding from sewerage and infrastructure

Following heavy rainfall and run-off, rivers rose rapidly, peaking on 8 January. The extreme nature of the weather and flooding meant that the Environment Agency's flood models were not very accurate and did not predict the magnitude of the flood event well. 50% of residents in the flood risk area had not signed up to receive a warning.

Carlisle was cut off and awash for some time on 8 January, with flood waters nearing the second floors of a few houses, leaving residents stranded. Some had to be airlifted off the roofs of their homes. Evacuation was dangerous in darkness and high winds. 2.5 metres of water flooded the fire station and police station adding to the problem of help by these services.

Flooding in the Future

Climate change is predicted to result in changes to flooding in the whole of the UK over the next 50 years. Changes in rainfall patterns could mean that there is an increase in the amount, duration and frequency of rainfall events.

It is very difficult to estimate future large floods reliably, but most scientists consider thatclimate change is likely to lead to different patterns of rainfall, which might lead to an increase in flood hazards in the UK.

Predictions for the Eden catchment indicate that winter rainfall (and therefore flood flows) might increase by as much as 15 to 20% by 2050, leading to increased flooding in urban areas. Future scenarios will be investigated by the Environment Agency to see the effects on existing flood defences.

As a result of the 2005 flood event, the Environment Agency produced a flood alleviation scheme to reduce the current and future risk of flooding.

The Environment Agency produced plans for a £12 million project to improve defences along the Petteril and Eden east of Carlisle. Work began in May 2007 and finished in spring 2008. Embankments along the two rivers were re-built to make them higher and wider, new flood walls were built, as well as drain-down sluices so that water trapped behind the defences would be able to drain away quickly. The scheme is designed to give protection against a 0.5 average probability event (1 in 200 years): it will reduce flood risk to 1,500 properties in the Warwick Road and Botcherby area of Carlisle.

A second £24 million project aims to protect the city centre, Caldewgate and Denton Holme, reducing the risk of flooding to the west of Carlisle along the River Caldew and River Eden. It will include floodwalls and embankments along the Rivers Caldew and Eden and a pumping station that will pump water from the Little Caldew to the River Caldew when river levels pose a flood risk. 

Earthquakes

Just a quick post. A short video to introduce earthquakes linked to the Haiti post below. I found it on Teachers TV which has a good selection of short videos that could be useful in the classroom.

Video can be found here.

Haiti

Following on from the concluding lines of the last post where Rachael discussed the important link between both human and physical processes, this post will highlight an example of how both concepts directly affect each other.

On Tuesday 12th January, 2010 a magnitude 7.0 earthquake struck Haiti and caused huge devastation. Reports estimated that over 200,000 people died, 1,000,000 had been made homeless and hundreds of thousands of homes and businesses had been destroyed. The following relief effort that began immediately often encountered problems which delayed necessary supplies. These problems stemmed from the human processes that had occurred for decades before the earthquake struck.

The infrastructure of Haiti was extremely poor. It was seen as the poorest nation in the world and had little exports to build its growth. What fuel, electricity and medical infrastructure did exist was demolished by the earthquake and was therefore unable to assist in the relief effort. There were frequent landslides during the aftershocks. The earth had already been made unstable due to the population stripping it of trees and vegetation to be used as firewood and building materials. The focus now is on the continued re-build of Haiti but more problems lie ahead for its inhabitants.

I have only scratched the surface in terms of the Haiti as a case study and there are thousands of websites available where further information can be gathered. Haiti is an excellent example of an event where the link between human and physical processes is clearly defined and one which would be suitable for classroom discussion. The video here is a short report by CBS news which clearly shows the devastation.

What are human and physical processes?

Physical geography is the strand of natural science which deals with the study of processes and patterns in the natural environment. Within the body of physical geography, the Earth is often split into several spheres or environments, the main ones being the atmosphere, biosphere, cryosphere, geosphere, hydrosphere, lithosphere and pedosphere. Research in physical geography is often interdisciplinary and uses the system approach.

Human geography is the study of human use and understanding of the world and the processes which have affected it. Human geography broadly differs from physical geography in that it has a greater focus on studying intangible or abstract patterns surrounding human activity and is more receptive to qualitative research methodologies. It encompasses most of the aspects of the social sciences.

While the major focus on human geography is not the physical landscape of the Earth, it is not possible to discuss human geography without going into the physical landscape with which human activities are being played out, and environmental geography which is an important link between the two.

Why are human and physical processes important?

The National Curriculum names human and physical processes as one of the seven key concepts that underpin geography.

'These processes cause change and development in places and can be used to explain patterns and distributions. Understanding these processes help pupils to imagine alternative futures for places and for the people who live and work in them.'

Welcome

Welcome to our blog discussing the human and physical processes that affect the world. It is designed to assist our learning and understanding of geography in regards to the National Curriculum at Key Stage 3.

Hopefully it will provide everyone with an insight into geography and also answer any questions you may have. It will also attempt to discuss the various interactions between both human and physical processes and how they work to shape the world in which we live.