Tuesday, 1 April 2014

Lancaster University team warns wetter winters may increase river pollution

Image courtesy Lancaster University
Warmer, wetter winters could lower the quality of our rivers, according to warnings from Lancaster University environmental scientists.

As farmers try to cope with waterlogged soil, following one of the wettest Januarys recorded since rainfall records began in 1910, a Lancaster University-led team of researchers has begun work on a large new collaborative project to help understand nutrient runoff from agricultural land and work out how it affects the quality of our rivers.

Professor Phil Haygarth, of the Lancaster Environment Centre, is leading the three-year, Natural Environment Research Council-funded study.

The project - Nutrients in Catchments to 2050 - involves researchers at Lancaster University, the Met Office Hadley Centre, Bangor University and Liverpool University and has associated partners at the James Hutton Institute, University of East Anglia, Anglia Ruskin University and Rothamsted Research.

"If winters continue to be warmer and wetter as predicted, increased rainfall could increase water pollution from agricultural land," says Professor Haygarth.

Nutrients, such as phosphorus and nitrogen are essential to plant and animal growth, but too many nutrients cause excessive plant growth and algal blooms in rivers and lakes. These suffocate fish and other organisms and require costly remediation by water supply companies.

Fertilisers and manures washed off in storms are a major source of nutrients, with more than 60% of the nitrogen and 25% of the phosphorus in our rivers coming from agriculture.

“Most of this nutrient transport occurs in a few large and intense rain events, particularly if these coincide with periods of bare soil or recently applied manure or fertiliser,” said Professor Haygarth. “If future climate trends suggest more frequent, more extreme rainfall events, then nutrient runoff could increase, unless we plan land management activities to account for this.”

New data, recorded every half hour by the Eden Demonstration Test Catchment programme, (a related collaborative project involving Lancaster University and partners) is being used by the team to improve understanding of how phosphorus moves in the agricultural landscape.

“This data contains unprecedented detail and enables us to link the driving forces with the nutrients in the river,” said Dr Mary Ockenden, Senior Research Associate at Lancaster University. “We can start to unpick the effect of conditions such as a dry period followed by a large storm.”

Lancaster University’s Professor Keith Beven, who leads the water quality modelling in the Nutrients in Catchments to 2050 project, said: “At the moment, water quality predictions are very uncertain, often because we do not have enough data to test computer simulations rigorously. However, this project enables us to test several different models with the new high-frequency data and to learn from their shortcomings.”

Scientists from the project have also met with farmers and landowners to discuss how changes in climate have affected land use and farming in the Eden Valley in Cumbria.

The new project will harness this experience and use information from similar meetings around the UK to develop land use scenarios for the future. These will then be combined with climate data to make predictions about water quality in the future.

The Eden Demonstration Test Catchment team involves researchers from Lancaster University, Newcastle University, Durham University, Eden Rivers Trust and other project partners. More info: http://www.edendtc.org.uk/

The NUTCAT-2050 team at Lancaster University includes Professor Phil Haygarth, Professor Keith Beven, Dr Mary Ockenden, Dr Michael Hollaway, Dr Catherine Wearing and Kirsty Ross

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