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LOCAR

Reports and key findings

River valleys and climate change

Chalk streams are significant sources of greenhouse gases. Research found the methane produced and released per unit area of chalk stream was comparable to some UK peatlands. The methane emissions from all UK chalk streams (estimated at about 2.6 tonnes per year) are at least as big, if not bigger than, emissions from groundwaters across the entire catchments of these chalk streams (estimated at 1.2 tonnes per year).

River valleys as the kidneys of the environment

The river valley floor and stream channel form an important 'bioreactor'. They transform the chemistry of nitrogen and potassium supplied from the catchment, and help modify the flow of nutrients into major rivers and coastal zones. Drought alters the way this 'bioreactor' performs. Our new understanding of this will contribute to creating sustainable rural economies.

The nutrient time-bomb

Complex groundwater flows in chalk mean that much of the massive amount of nutrients applied to fields in recent decades is still in the groundwater, and may take 15 years to reach stream channels. Changes in land-use practices will not improve river water quality for more than a decade.

Making space for water and plant life

By modifying channel hydraulics and trapping sediments, riparian and aquatic plants change habitats, contribute to biogeochemical processes and alter conditions for fish. So the way channels are maintained for flood and fisheries management affects biodiversity, habitat and water quality.

Understanding where the underground water goes

LOCAR research has re-interpreted the groundwater catchment and groundwater flows around the Pang, showing that much of the water in the chalk flows directly to the Thames. Detailed work is helping to improve the models used in forecasting available groundwater resources. It has already shown that there are both rapid and extremely slow water pathways through the chalk.

Tracing the source of sediment that silts up channels

Detailed field measurements clearly demonstrate that the shift from pasture to cultivation in southern England affects rivers. Cultivated fields yielded 50 per cent of the sediment load in the Frome and 69 per cent in the Lambourn.

The influence of geology

The programme has provided new information showing how glacial drift in the Tern catchment influences how rainwater moves into the ground to replenish the underground supplies many parts of the Midlands of England depend on. The drift is more complex than previous maps indicate. Patches of sand allow rapid water movement, while lenses of clay may send the water sideways for considerable distances before it works its way into the sandstone below.

Case studies

The following case studies are linked to this research programme. Full details of each case study are available from NERC's Science Impacts Database.

Research helps implement the EU Water Framework Directive Synopsis: Research into river plants and how they affect a stream's health is helping the Environment Agency implement the EU Water Framework Directive.

Understanding underground water flow Synopsis: Research into stream-groundwater interactions in lowland chalk catchments should help water managers decide how much water to extract, and how catchments will respond.

Higher than expected risk of pollution to water supply wells Synopsis: Research showing that water moves faster than expected through an aquifer could help protect groundwater supplies.

Preparing for pollution in our water supplies Synopsis: Research into how fast water - and pollution - moves through the chalk downs of Southern England could help tackle agricultural chemicals leaching into drinking water.

Soil erosion in rivers - finding where it comes from and goes to Synopsis: Ploughed fields, not pasture or eroding banks, are the main source of damaging soil erosion in lowland rivers. The finding is informing new farming initiatives.

Chalk is good at filtering out pollution from groundwater, but some areas let contaminants through Synopsis: Most of Britain's chalk aquifer has a large capacity for reducing pollution entering groundwater, but where streams sink into the ground dissolved material and viruses could enter domestic supplies relatively quickly.

NERC's Lowland Catchment Research programme (LOCAR) is worth £2m-£9m to Britain's economy Synopsis: NERC's Lowland Catchment Research Programme will reduce the cost of implementing the European Union's Water Framework Directive and its Nitrates and Habitats Directives, bringing between £2m and £9m of benefits to the British economy.