Chalk Rivers, The State of Englands Chalk Rivers

Land use and river habitats

The character of chalk rivers today reflects a long history of management. Evidence of dredging work carried out decades ago can still be seen. The drainage of wetlands and abandonment of water meadows reflect the changing patterns of agriculture in the valleys. Today, intensive agricultural practices and urban development have become more prominent in many chalk river catchments.

Land use

Compared with England as a whole, chalk river catchments have a higher proportion of arable land and less grassland: 49% of chalk river catchments are now in arable use (36% for England as a whole); 27% is grassland (38% for England); and 10% is urbanised. Woodland covers only 5% of chalk river catchments.

 

 

(c) Dennis Bright
Road development has adversely changed the character of many chalk rivers

Figure 4 Proportion of arable land in chalk river catchments in 2000

Source: Environment Agency and Centre for Ecology and Hydrology


(c) Dennis Bright
Intensive agriculture

The potential effects from cultivated and urbanised land include increased run-off of rainwater and soil erosion. These in turn increase the risk of sediments, fertilisers and pesticides entering rivers. Also, urban land increases local pollution risks from oil and other chemicals.

A widespread problem in chalk rivers is that river-bed gravels are clogged up with sediment. This reduces the survival of eggs and fry of salmon and trout. About 90% of fine sediment in salmon spawning gravels in the Test, Itchen and Kennet rivers comes from surrounding land.

Habitat quality of chalk rivers

A top quality chalk river has a mosaic of habitats; gravel runs and glides, water-crowfoot beds, side channels, wet woodland and marshes.

Results from the national River Habitat Survey (RHS) during 1994-1997 showed that half of the chalk river sites surveyed have high or very high channel habitat quality. However, nearly one-third have poor habitat quality, because of the cumulative effects of urban land use, intensive agriculture and increased demand for water.

Farming practices

At many chalk river locations, environmental schemes and landowners with fishing interests have improved damaged habitats. Steps taken include reducing livestock numbers and erecting bankside fencing. Several Countryside Stewardship scheme agreements on chalk rivers are helping to raise groundwater levels and return arable land to pasture. There are also Landcare projects in the Test, Itchen, Wensum, Kennet and Avon catchments. These enable farmers to reduce the impacts on chalk rivers of diffuse pollution, such as silt, pesticides and nutrients.

Habitat rehabilitation

The future of wildlife in chalk rivers depends on us. We need to tackle problems of river flow, water quality and damaged habitats. There is good evidence that a diverse habitat within river systems is more efficient at counter-acting effects of polluted water and low flows. The problems are complex, but rehabilitation schemes show that much can be done.

Flood defences now use environmentally sympathetic engineering techniques to minimise impacts. Water level management plans aim to ensure a balance between conservation, landscape and agricultural activities.


Harvesting maize - a common arable crop in chalk river catchments

Figure 5 The quality of chalk river habitats as assessed using River Habitat Survey data

Source: Environment Agency, River Habitat Survey, 779 sites, 1994-1997


 

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