Land drainage in England and Wales : report.

  • Great Britain. Central Advisory Water Committee. Land Drainage Legislation Sub-Committee
Date:
1951
Catalogue details

Licence: Public Domain Mark

Credit: Land drainage in England and Wales : report. Source: Wellcome Collection.

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    To give two current examples, the Great Ouse Catchment Board are embarking on a major flood protection scheme involving the construction of entirely new channels to secure the safe passage of upland waters through or around the fen area of the South Level to the sea; and the Welland Catchment Board have already made substantial progress with a less extensive scheme of a similar character. Effect of drainage in the uplands 15. We are aware that in some quarters it is strongly held that improved drainage in the uplands has greatly increased the threat of flooding to the lowlands. There is an opposing body of opinion that maintains that the execution of drainage works creates storage capacity in the land, thereby reducing rather than increasing the flood discharge. This conflict of opinion and the apparent lack of concrete evidence on the subject led us to seek the technical advice of the Ministry of Agriculture and Fisheries, and we asked them to call together a panel of technical experts to consider the problem. As we had also received suggestions that land drainage operations adversely affected water resources, we asked them to investigate that subject also, and we gave them the following terms of reference :— “To examine broadly the information available as to the effect of land drainage operations on the flow in rivers and upon water resources; to . consider what practical steps might be taken, if necessary, by drainage authorities to conserve water without impinging on the functions and interests of water undertakers and other river users ; and to report upon the methods at present apse ae by drainage authorities to enable riparian users to obtain a supply of water.” 16. The Panel’s report is contained in Appendix IV. They state that the factors involved in the problems before them are many and variable, and that in their investigations they have been seriously handicapped by the lack of observational data. As the investigation of possible repercussions of land drainage operations on both flood risk and water supply is a matter of consider- able importance, we support their recommendation that it be further examined. They have concluded that it is impossible to say whether underdrainage or moorland gripping have any significant effect on flood risk. They point out, however, that since 1940 the land which has received Government grant in respect of underdrainage represents only 2 per cent. of the agricultural land of England and Wales, and it seems likely, therefore, that the effects of this type of drainage, if existent at all, will not be serious. Pending conclusive evidence to the contrary, the Panel are of the opinion that local channel improvement works or the improvement of control structures may result in increased flood peaks downstream ; and, as the cumulative effects of many improvements to ditches, streams and rivers may be substantial in the lower reaches, they recommend that before such works are undertaken the possible effects downstream should be balanced against the benefits likely to accrue. They advise that throughout a catchment area there should be a clear con- ception of the objectives of the improvement works. We consider that those responsible for the planning of drainage works would do well to bear these suggestions in mind. 17. As regards the remaining matters on which the Panel were asked to report, it will be noted that they consider that drainage authorities in general are alive to the need for providing a supply of water for agricultural and other purposes.. Further recommendations on these important and_ intricate problems will be found in the Technical Panel’s report,
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