Chalk Rivers, The State of Englands Chalk Rivers

The character of chalk rivers

Location

There are 161 chalk rivers and streams identified in the report. They follow the band of chalk that sweeps diagonally across England. They occur nowhere else in the UK, and are very rare in the world as a whole.

Appearance and character

Chalk river water is crystal clear. This is because the rainwater is purified as it percolates through the chalk and emerges as springs in the valley floor. As a result, the water is very alkaline or hard, with a relatively constant temperature.

Figure 1 Chalk rivers and their associated wildlife conservation designations

All Special Protection Areas are Sites of Special Scientific Interest
Source: Environment Agency and English Nature


Upper reaches of a classic chalk river crystal clear water and healthy plant growth

River flow changes seasonally. It rises gradually during the winter as the aquifer is replenished, and gently declines in the summer and autumn as the aquifer diminishes. In some of the headwaters, known as winterbournes, this cycle results in natural drying for a few months in the summer and autumn. Further downstream, classic chalk rivers have relatively constant flows throughout the year.

Culture

Englands chalk rivers are an intrinsic part of our cultural heritage. Several are world-famous for their fly-fishing Hampshires famous Rivers Test and Itchen are heralded as the birthplace of this skilful pursuit. Over the centuries, chalk rivers have inspired several famous writers and artists: Isaac Walton, the father of angling, wrote The Compleat Angler over 350 years ago; John Constable captured the beauty of the Hampshire Avon and its surrounding water meadows in his painting of Salisbury cathedral. The histories of other famous cathedral cities are entwined with the chalk rivers that flow through them: Winchester with the River Itchen; Canterbury with the River Stour; and Norwich with the River Wensum.

History

The chalk rivers we see today reflect a long history of human intervention. Comparatively few remain in a natural state.

After the prehistoric woodland clearances, most of the remaining wet woodlands in the valleys were cleared. Channels were dug, deepened and straightened so that the land could be drained for agriculture. The Romans harnessed the reliable flows to power water mills. From the 17th to the 19th centuries carrier streams were created to flood and irrigate the water meadows where sheep and cattle grazed.

Chalk rivers and their aquifers have long provided water for drinking and industry. However over the past 100 years, there have been significant increases in water abstraction, effluent discharges and river engineering works for land drainage and flood defence. As populations expand and commerce grows, we exert ever-greater pressures on our chalk rivers.


(c) Still Imaging
Water meadows on the River Avon at Downton


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