The Met Office’s announcement last week that 2012 was the wettest year ever recorded in England will come as no surprise to many of us. Over the last few months we have seen widespread flooding due to surface water accumulation and overbank flows.
What would be easier to forget is that less than 12 months ago many parts of England were experiencing drought conditions. There has been a massive transformation in the status of our hydrological regime from depleted groundwater aquifers to catchment-scale flooding.
So what’s going on? The theory goes that global climate change is leading to an increase in the frequency of extreme weather events. This means more regular heavy showers and prolonged drought events.
Such conditions present river managers with several major challenges:
Extreme weather events test the robustness of our river management infrastructure. Flood defence structures designed to endure a 1 in 100 year flood will fail more frequently if a 1 in 100 year flood becomes a 1 in 50 year flood. Equally, reservoirs may become ineffective for water storage if they are situated in drought-prone areas, or locations that are disconnected from drought-prone areas.
Unpredictable weather places pressure upon our water resources. Several rivers in the south-east of England are considered to be over-abstracted under current climate conditions and it is anticipated this situation will worsen in the future. Ever-increasing demand for water, whether for direct consumption, irrigation or industry, further exacerbates the problem.
A changing climate affects our ability to predict and forecast. Some of our gauging stations have been online for nearly 50 years, and have captured invaluable information on the changing hydrological conditions of our rivers over this time. In many instances these data can be used in conjunction with meteorological data to produce useful models explaining how our rivers might respond to future climate change. In others, gauging weirs designed to a particular specification (i.e. to remain functional even during Q95 and Q5 flows) may no longer work effectively.
Ecological objectives may move, be forgotten or neglected. Environmental legislation such as the Habitats Directive and the Water Framework Directive are easily overlooked when you’re trying to prevent someone’s home from flooding. River regulators need to make sure they prioritise the respective concerns and strive to fulfil our ecological obligations in the aftermath of extreme events.
Perhaps most importantly, extreme weather often results in an extreme river basin response, and this can be dangerous. A recent article in the Guardian newspaper highlights the costs of 2012, with nine lives lost to flooding and millions of pounds of damage. Whilst only improved flood defences can mitigate against economic losses, education alone can help save lives. The Environment Agency and emergency services used Twitter and other social media tirelessly over 2012 to make people #floodaware, yet we still saw instances of the public taking unnecessary risks. River managers must work hard to ensure people realise the risk to life posed by flooding.
From a purely geomorphological perspective, 2012 was amazing. From a river management perspective, let’s hope 2013 doesn’t give us anywhere near as much trouble!