An evaluation of inter-basin water transfers as a mechanism for augmenting salmonid and grayling habitat in the River Wear, North-East England

✍ Scribed by Gibbins, C. N. ;Heslop, J.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 733 KB
• Volume: 14
• Category: Article
• ISSN: 0886-9375
• DOI: 10.1002/(sici)1099-1646(199807/08)14:4<357::aid-rrr508>3.0.co;2-8

✦ Synopsis

Transfers of water from the Kielder system have been used for 12 years to avoid low flow problems in the River Wear. Transfers are scheduled to avoid breaches of the river's statutory Minimum Maintained Flow (MMF). Despite this routine use, the role of transfers in augmenting instream habitat has never been evaluated. A physical habitat simulation (PHABSIM) study was undertaken in 1996 to investigate the influence of transfers and the MMF policy on brown trout Salmo trutta, Atlantic salmon Salmo salar and grayling Thymallus thymallus instream habitat at three sites on the Wear.

Transfers support total habitat levels up to 10% greater than unregulated conditions. They impact usable instream habitat (weighted usable area) to a much greater extent. For salmon parr, the species/lifestage whose habitat is most limited by low flows, transfers have maintained relatively stable usable habitat levels during periods when otherwise they would have fallen by as much as 70%. The MMF policy results in minimum flow values which are higher than those which would have been set using the Montana Method and the availability of salmon parr usable habitat does not fall below 10% of its mean annual value. Judged in these terms, the MMF-based transfer regime has played a positive role in avoiding extreme habitat loss in the Wear.

Simulations of four alternative Kielder transfer release policies indicate that near-optimum habitat levels could be maintained throughout summer low flow periods. However, this would result in unnatural temporal patterns of flow and habitat availability.