The influence of recent environmental change on flooding and sediment fluxes in the Yorkshire Ouse basin

✍ Scribed by Sean A. Longfield; Mark G. Macklin

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 332 KB
• Volume: 13
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(199905)13:7<1051::aid-hyp789>3.0.co;2-r

✦ Synopsis

This study attempts to establish causes of historical variations in ¯ood frequency and magnitude in a 119-year ¯ood stage record at York, and assess its likely eects on ¯uxes of ®ne sediment and associated base metal contaminants. Climatic controls of ¯ooding are evaluated through analysis of synoptic ¯ood generation, and large-scale land use changes are also considered in terms of their in¯uence on food frequency and magnitude and sediment availability. The late nineteenth century was characterized by low ¯ood frequency and magnitude, but, as a consequence of upland metal mining, contaminant concentrations and downstream ®ne sediment delivery would have been high. A further decline in ¯ood frequency and magnitude between 1904 and 1943, combined with the cessation of base metal mining, resulted in a decline of sediment and contaminant ¯uxes. Between 1944 and 1968 increases in upland drainage, changes in agricultural practices and high ¯ood frequency and magnitude resulted in signi®cantly enhanced sediment ¯uxes. Rates of ¯ux declined between 1969 and 1977 owing to extremely low ¯ood frequencies and magnitudes. In the last two decades there have been a series of extreme magnitude ¯oods, which through remobilization of mining-contaminated alluvium have resulted in high pollutant metal mining loads, probably approaching those of the late nineteenth century. In an historical context it appears that the LOIS monitoring programme has been undertaken in a period of extremely high ¯ood frequency and magnitude in the UK, and signi®cantly enhanced sediment and contaminant metal ¯ux. Analysis of synoptic ¯ood generation suggests that any future increase in the frequency and vigour of cyclonic atmospheric circulations may result in a higher frequency of extreme ¯oods and consequently increased sediment ¯uxes.