4 th Internat. Symposium on Flood Defence – Toronto/CA Sensitivity analysis of lapse rate and corresponding elevation of the snowline Limited data availability and its impact on snow and glacier melt Rinderer M., Achleitner S., Asztalos J., Kirnbauer R.
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4 th Internat. Symposium on Flood Defence – Toronto/CA Sensitivity analysis of lapse rate and corresponding elevation of the snowline Limited data availability.
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4th Internat. Symposium on Flood Defence – Toronto/CA
Sensitivity analysis of lapse rate and corresponding elevation of the snowline
Limited data availability and its impact on snow and glacier melt
Rinderer M., Achleitner S., Asztalos J., Kirnbauer R.
According tomy model
it‘s snowingup there!
Outline
Introduction
Aims and Questions
Method
Analysis and Results
Conclusions
Perspectives
Introduction – Roll of Snow and Glacier Melt Modelling
Fluvial regime of mountainous regions Intermediate-term and long-term retention of precipitation -> influence on
amount of runoff generated during a rainfall event (1) Elevation of the temporary snowline (snow/rain) (2) System conditions: snowfree: immediate runoff/infiltration; snow-
covered: temporary absorption and retention by the snow cover
Water is released in warmer periods Days, weeks, month later
Not only precipitation but also snow and glacier melt influence fluvial regime
Importance for flood forecasting in glaciated areas
Introduction – Flood Forecasting System HOPI
Hybrid-model concept Main river course:
hydraulic model FluxDSS/DESIGNER
Tributary catchments: hydrological model HQsim
Glacier melt: energy-balance model SES
Introduction – Snow and Ice Melt Model SES
photo: USI/Ibk
Physically-based, spatially distributed, energy balance model Based on a snow melt model by Blöschl et al. (1987) and
Blöschl et al. (1991), further developed by Ansztalos (2004) grid based model (1) distributed accumulation of snow (2) snow, firn and ice melt in a glaciated catchment resulting runoff calculated for individual grid elements is
routed to the catchment outlet using a Nash-Cascade approach
Meteologolical input lapse rate air temperature
Introduction – Determination of Snowline
Modelling snowline: Not a straight line but a zone of
transition Simulated using a lower and an
upper temperature-boundary to separate snowfall from rain
In the transition-zone a portion is considered to be snow, the rest rain
Highest weather station measuring air temperature situated at 2850 m a.s.l.
Glaciated area ~ 3000 – 3700 m a.s.l.
-> Temperature extrapolated to glaciated area using linear regression method
photo: USI/Ibk
Questions
1. How well is the temperature in the snow- and ice-region estimated by the simple linear regression method?
2. Which set of stations is most reliable for calculating lapse rate and corresponding elevation of the snowline?
3. How sensitive is the approach to limited data availability?