The role of snowpack in producing floods under heavy rainfall

In order to understand the hydrological response of rain-on-snow events, ar tificial rains with different intensity and duration were simulated on a sn ow plot consisting of natural snowpack, and the behaviour of the emerging o utflow was studied. This study was carried out in the Austrian Alps. Measur ements of meteorological parameters, soil temperature and snowpack properti es were also made. It was found that the presence of ice layers increased t he liquid water holding capacity of the snowpack to more than two times tha t of an homogeneous snowpack. Under the saturated conditions of the snowpac k, rainwater moved with a speed of about 6 m h(-1) suggesting that the spee d of rainwater may be several times higher than the normal snowmelt transmi ssion through the snowpack under non-rainy conditions. Most of the input ap peared as runoff under heavy rainy conditions because the snowpack was quic kly saturated and conditioned to yield the maximum runoff.