A team of researchers, including scientists from the Centre for Ecology & Hydrology (CEH) and the British Geological Survey (BGS), have just published research into the impacts of peri-urban development on storm runoff. Peri-urban areas are the spaces – between the city and the countryside – containing hybrid landscapes with both urban and rural characteristics.Flood rushing past a gate

The new paper1, published in Journal of Hydrology, utilizes a dedicated urban monitoring programme within Swindon in Wiltshire, UK to calibrate a hydrological model to a highly developed scenario of land-use and then to look back in time, or backcast, the progressive impacts of development from the previously rural state of the catchments in question.

The research team used a novel method for mapping long-term change in impervious cover, surfaces such as pavements, roads, and driveways that are covered by impenetrable materials such as concrete and brick. The method used was published in a previous journal article2 in the International Journal of Applied Earth Observation and Geoinformation, by collaboration between scientists at CEH and BGS.

The study results demonstrated an increase in impervious cover within the peri-urban catchment from 11% in 1960 to 44% in 2010. The research team found that increases in peak flows will be greatest at low levels of urbanisation and that the introduction of stormwater conveyance systems can significantly increase the ‘flashiness’ of storm runoff above that attributed to impervious area alone.

James Miller, the lead Centre for Ecology & Hydrology researcher, said, “This work provides clear evidence of the profound impacts that developing rural areas into housing and commerce can have on the response of a catchment to storm events. Without appropriate planning and mitigation measures this could lead to an increased likelihood of localised and downstream flooding."

He added, “We have been taking a leading role in answering questions relating to the impacts of urbanisation on water quantity and quality. A key driver is that current methods for estimating flood risk do not robustly account for the impacts of changing land use in the form of urbanisation and, with a projected population increase of 16% for the UK over the next 20 years, there will be a significant expansion of urban areas."

A team of researchers led by Dr Mike Hutchins of CEH is currently undertaking an ambitious programme of research, entitled POLLCURB, to understand how predicted future population growth and climate change might impact upon water quantity and quality within the Thames basin. POLLCURB activities are currently focused upon monitoring water quantity and quality across urban areas within the Thames basin and involves citizen scientists.

James Miller concluded, “Improving our empirical understanding of the relationship between urbanisation and flood risk or pollution enables more appropriate and effective mitigation strategies to deal with natural hazards and to ensure sustainable development for such growth in the long-term.”

Additional information

1Miller, J. D., Kjeldsen, T., Kim, H, Packman, J., Grebby, S., Dearden, R. (2014) Assessing the impact of urbanization on storm runoff in a peri-urban catchment using long-term change in impervious cover. Journal of Hydrology (in press). doi: 10.1016/j.jhydrol.2014.04.011

2Miller, J. D., & Grebby, S. Mapping long-term temporal change in imperviousness using topographic maps. International Journal of Applied Earth Observations and Geoinformation. 30. 9-20. doi: 10.1016/j.jag.2014.01.002

POLLCurb website