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| Titel |
Spatial and temporal variations in the occurrence of low flow events in the UK |
| VerfasserIn |
A. R. Young, C. E. Round, A. Gustard |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 4, no. 1 ; Nr. 4, no. 1, S.35-45 |
| Datensatznummer |
250001517
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| Publikation (Nr.) |
 copernicus.org/hess-4-35-2000.pdf |
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| Zusammenfassung |
Information on the magnitude and variability of low river flows
at the river reach scale is central to most aspects of water resource and water
quality management. Within the UK, river stretches with permanent gauging
stations represent less than one percent of the total number of river stretches
mapped at a scale of 1:50,000 and fewer that 20% of gauged catchments can be
regarded as having natural flow regimes. This has led to the development of
simple, multivariate models for predicting average annual natural flow duration
statistics through relationships with catchment characteristics. One assumption
within these models is that low flows occur at the same time at all points
within a catchment, irrespective of the hydrogeological nature and climatic
condition of the catchment.
This paper discusses the implications of spatial variations in the timing of low
flow events for this type of model. Differences in the timing of the mean day of
occurrence of the annual Q95 flow in UK catchments can be identified with low
flows occurring earlier in the year within impermeable dry catchments and later
in the year for wet permeable catchments. However, any differences in the mean
day of occurrence between different catchments are generally masked by the
magnitude of the inter-year variability in the day of occurrence.
From analysis of linear combinations of flow statistics from nearest-neighbour
gauged catchments, the paper demonstrates that the assumption of temporal
coherence of low flows will generally result in an under-estimate of Q95; these
underestimates are more significant for pairs of impermeable catchments than for
combinations of permeable catchments and impermeable-permeable catchments. |
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