River Response to Recent Environmental Change in the Yorkshire Ouse Basin, Northern England
River response to recent environmental change in the Yorkshire Ouse basin, northern England. Sean Anthony Longfield, B.Sc. (H ons) 'N/ Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds School of Geography July 1998 The candidate confirms that the work submitted is his own and that appropriate credit has been given where reference has been made to the w'ork of others II A b s t r a c t Longfield, S.A. 1998. River response to recent environmental change in the Yorkshire Ouse basin, northern England. University of Leeds, Ph.D. This study examines historical variations in flood frequency and magnitude in the Yorkshire Ouse basin, northern England, over the last 900 years. The causes of temporal and spatial variations in flooding are evaluated through investigation of climatic and land-use controls. Documentary evidence of flooding and climate suggests that a series of large floods between 1263 and 1360 were associated with climatic deterioration from the Medieval Optimum. A shift to generally milder conditions between 1361 and 1549 resulted in no floods being documented in the Ouse basin The frequency of large magnitude floods increased dramatically between 1550 and 1680, as a result of low temperatures, increased surface wetness, more frequent snowfall and a southward shift of prevailing storm tracks over middle latitudes, associated with the onset of the "Little Ice Age’. In contrast, during a wanner phase of the Little Ice Age, between 1681 and 1763, the frequency of localised summer flooding increased in the Ouse basin due to more frequent high intensity, short duration convective storms.
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