The impact of variable snow pack accumulation on a major Scottish water resource

In regions such as northern Scotland, where winter temperatures are such th at the occurrence of snow is borderline under the present climate, potentia l changes affecting precipitation and temperature regimes may have a dispro portionately large impact on snow processes and hydrological behaviour. The physical characteristics of mountainous areas in Scotland mean that the sp atial variability of snowpack accumulation is high, as well as the temporal variability caused by the climate. There have been few modelling studies a imed at assessing the significance of snow resources in these areas and non e that have adopted a spatially distributed approach. This paper describes the approach taken in applying a new distributed model to a headwater catch ment in the Cairngorm Mountains. The results demonstrate the importance of wind on re-distributing snow to create deep accumulations in small sheltere d pockets. These accumulations are shown to be important in sustaining base flows in the rivers, long after snow has melted from the rest of the catchm ent. The model has also produced a first set of maps showing how predicted snow depths vary across the catchment through the winter. (C) 2001 Elsevier Science B.V. All rights reserved.