Relationships between extreme daily precipitation and topography in a mountainous region: a case study in Scotland

✍ Scribed by Prudhomme, Christel; Reed, Duncan W.

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 328 KB
• Volume: 18
• Category: Article
• ISSN: 0899-8418
• DOI: 10.1002/(sici)1097-0088(19981115)18:13<1439::aid-joc320>3.0.co;2-7

✦ Synopsis

The spatial pattern of precipitation is known to be highly dependent on meteorological conditions and relief. But the relationships between precipitation and topography in mountainous areas are not very well known, partly because of the complex topography in these regions, and partly because of the sparsity of information available to study such relationships in high elevation areas. Moreover, studies are usually focused on mean annual precipitation, and so the patterns of extreme precipitation at short time steps, like daily, remain difficult to model.

Daily annual maximum precipitation for 1003 gauges in Scotland, the most mountainous region of the United Kingdom, are studied to investigate the relationships between the median of the daily rainfall annual maximum, RMED, and the topography. A set of 14 topographical variables, some of them defined with respect to one of eight cardinal directions, are calculated from a 1×1 km digital terrain model (DTM). A particular effort has been made to improve the definition of some of the topographical variables suggested in the literature, either to provide a better physical definition or to better reflect the spatial variability of the topography.

Single and multiple regression analyses have been made in some parts of the Highlands, leading to a 4-parameter model. This model is a mixture of geographical parameters (distance from the sea in opposing directions) and of topographical parameters (obstruction against the prevailing winds, and roughness between the main moisture source and the gauge). Special care has been taken to define a model whose physical sense is consistent with the meteorological conditions and whose parameters are not too interdependent.