Following torrential rainfall, the River Don burst its banks in early November 2019 at several places along its course in South Yorkshire. The entire village of Fishlake, comprising around seven hundred households and situated just north of the town of Doncaster, was evacuated on November 9 after a “danger to life” flood was warning issued by the Environmental Agency. The village was rapidly submerged, with the villagers relying heavily on assistance from the neighbouring village of Stainforth. Predictably, politicians, starting with Labour leader Jeremy Corbyn, closely followed by Jo Swinson of the Liberal Democrats, and belatedly by Prime Minister Boris Johnson, visited the flood-stricken area and thereafter engaged in the usual political mud-slinging and point scoring. Johnson, in particular, refused to declare a “national emergency” despite calls from opposition leaders to do so .
Flooding in the Don Valley is not a new phenomenon. The area was also affected by the floods of summer 2007. The River Don, which arises in the Peak District, flows eastwards for 70 miles from Derbyshire, through South Yorkshire, before joining the River Ouse at Goole in East Yorkshire. Its course takes it past the major population centres of Sheffield, Rotherham and Doncaster. Naturally, a repetition of flooding in the area has led to wider allegations of the neglect of issues affecting northern England by politicians in Westminster.
Going back to the basics: water is the basis of all human life, while at the same time capable of immense damage to people, animals, land and property. Water is the most abundant substance on Earth, with around 97 per cent contained in the oceans, which cover 70 per cent of the surface area of the planet, and with a further 2 per cent confined to the ice caps. There is a fixed amount of water in the Earth, which is continuously recycled in the so-called hydrological cycle.
Water occurs naturally in liquid, solid and gaseous states, makes transitions between these three states, and is continuously redistributed between the three compartments of the global system-the oceans, the continents or land mass, and the atmosphere. This cycling involves a complex combination of several processes, Evaporation of water into the atmosphere from the oceans and lakes is brought about by solar radiation and is followed by its return to the land or back to the oceans through precipitation. Precipitation involves the return of water in liquid (rainfall) or solid (snowfall, dew, frost) form. On return to land, water can undergo either infiltration (entry of water into the soil), transpiration (evaporation from vegetation), and runoff (surface flow of water, with eventual return back to the oceans via rivers).
Flooding represents an imbalance in these processes, leading to a undesirable accumulation of water in amounts over those necessary to sustain life and society. According to the Environment Agency, one in six properties (5.9 million homes) in England and Wales are at risk from river and coastal flooding.
The Don Valley is the catchment area or river basin for the River Don, covering an area of 714 square miles. Flooding in the Don Valley is an example of fluvial flooding, brought about by rivers bursting their banks, overflowing and then rapidly moving downstream, often following heavy rainfall. Increased rainfall is the main cause of flooding inland, as opposed to coastal flooding, which results from high tides, storm surges and waves. Global warming, through increased evaporation of ocean water, is predicted to cause more frequent and heavier rainfall in the future.
The question is: What can be done to prevent flooding and to limit the damage from floods? Firstly, those areas most at risk from flooding, which include riverside and floodplain locations prone to inland floods, need to be identified and prioritised for flood prevention measures. In this context, the UK government provides useful online information about the flood risk of individual postcode areas. Flood warnings and alerts are also provided by phone, email or text messages for homes and businesses at risk of flooding in high-risk areas.
Flood prevention is obviously preferable to reactive measures taken after floods have actually offered. Some hard defences, such as raised embankments and concrete walls or dykes to protect river banks, often prove to be ineffective. On the other hand, flood barriers, such as the Thames Water Barrier in London, have successfully protected some cities against an ever-present risk of floods. Natural flood defences can be provided by creating deliberate breaches in embankments, thereby diverting water to tracts of open land which can act as natural sponges to absorb floodwater, and also by planting trees and protecting existing wetlands . Future house building in flood plains needs to be actively discouraged, even though these low-lying and relatively flat areas are often preferred by builders and developers-despite the difficulties of insuring the new homes thus constructed. New constructions in flood-prone areas, where inevitable, should be built at an elevation of one metre from the ground surface.
Homes in flood-prone areas can be made more resilient to the effects of floodwater-by providing waterproof plastic panels to exterior doors, by sealing ground floors and by moving electrical sockets higher up the walls. Sandbags should be available to those households most at risk. Better resilience measures should be extended to local infrastructure as well.
Water is a great servant, but a dangerous master. Investment in flood prevention is infinitely preferable to managing a flood that is out of control. The Environment Agency needs adequate funding, and other resources, to support its critical role in flood prevention. Judging by television footage of locations and people affected by the current floods, we have a long way to go and yet this is an imperative in the light of rapidly changing climatic conditions.
Ashis Banerjee (originate from an area prone to flooding)