Trends in the Pattern and Variability of Rainfall in the Loch Lomond Basin, Scotland

Physical geography, Hydrologic sciences, Climate change

Ventura, Ana Maria Lopes

University:University of Glasgow

关键词: Physical geography, Hydrologic sciences, Climate change;   

Others  :  http://theses.gla.ac.uk/76399/1/13834163.pdf

来源: University of Glasgow

【 摘 要 】

The nature of present climatic change is causing general concern, mainly due to the assumption that this change is due to anthropogenic forcing. This study aims to examine annual and seasonal changes in rainfall regime over West Central Scotland and to evaluate the consequent wider effects on the area. For this purpose 14 series of monthly rainfall data were analysed from the records from 28 sites within and outside the Loch Lomond basin in West Central Scotland. Each series includes all of the records available, the shortest has 18 years and the longest has 121 years of record, with some series composed of a grouping of several stations. Gaps in the records are filled in the series by estimation and the homogeneity of the final data set is checked. The nature of temporal rainfall trends in pattern and variability over the Loch Lomond area is examined using different techniques of time-series analysis for annual (Oct.-Sep.), Winter half-year (Oct.-Mar.) and Summer half-year (Apr.-Sep.) rainfall amounts. The nature of spatial trends in the pattern and variability of rainfall is examined by isohyetal maps for standard periods of average annual rainfall. The different kinds of data presentation are examined for evidence of changes in the patterns of annual and seasonal increcises and decreases in dry and wet years, and in terms of interannual rainfall variability. The overall trends and changes in spatial variability are also investigated. The study confirms a marked trend towards increasing wetness over Central West Scotland during the last two decades as noted in earlier studies of wider coverage. From 1968/69 to 1991/92 the increase over the Loch Lomond basin was 76.6%. Furthermore it is demonstrated that this trend to increased rainfall has had no similar occurrence in the last 121 years, although important fluctuations have occurred. Spatially, the Northwest part of the Loch Lomond basin is wetter and the records indicate a greater rainfall increase in the recent two decades compared to the Southeast. Possible causes of increasing rainfall related to changes in the general circulation and local conditions and the wider implications for the hydrological system and land use are discussed. The trends towards an increase in rainfall are consistent with theoretical experiments related to global warming linked with an enhanced 'greenhouse effect', but it is possible that they may reflect a return to conditions of earlier periods. The results of this study are particularly significant as they serve as a detailed indicator of climate change in West Central Scotland and constitute the basis for future planning of basin management in the Loch Lomond area.