1. Snowpack indicator

2. Key message
Early accumulation of snowpack can decrease runoff and ground water recharge during the winter months
Lack on snowmelt can increase possibilities for drought during the spring and early summer
E.g. In Finland snowpack accumulation is from 10 to 30 % of yearly precipitation
The warming climate is predicted to increase variation in the snowpack

3. Relevance of the indicator
Snowpack is an essential part of water cycle in the northern parts of Europe and in the mountains
Snowpack is an indicator of drought risk
Not sufficient by itself !
Snowpack can be used to predict the drought risk during the coming spring and summer together with other drought indicators
Human abstraction plays no role in the snowpack indicator

4. The indicator Static snowpack indicator:
sSN = period of return of the annual maximum snowpack water equivalent in mm in water (=kg/m2 of snow)
provides information of the relative volume of the snowpack in the catchment in a given year, indicating possible drought
used for awareness raising and post evaluation of occurred droughts
Dynamic snowpack indicator:  (not tested yet)
dSN = period of return of the daily snowpack water equivalent in mm in water (=kg/m2 of snow)
provides information of the relative volume of the snowpack in the catchment on a daily basis, indicating drought risks especially in spring and early summer
used for forecasting future drought risks and for management purposes
Normal level
More than normal
Much more than normal
Less than normal
Much less than normal
10 %
One year on 10
10 years dry
25 %
One year on 4
4 years dry
75 %
3 years on 4
4 years wet
90 %
9 years on 10
10 years wet
Quantiles (statistical frequency of the levels for the same day/year)

5. River Paimionjoki pilot

6. Experiences Not sufficient indicator of drought by itself
Small snowpack doesn’t always mean risk of drought during the spring
if winter has been warm, the precipitation is not entirely accumulated into snowpack
Instead it may be stored in other natural and artificial storages (e.g. lakes, soil moisture) ensuring adequate runoff during spring and early summer
Not quite good indicator in small catchments with low proportion of lakes
The runoff from snow melt is rapid and the snowpack is quickly discharged downstream/ocean
Works better in bigger catchments ? Needs to be tested..
Gives essential additional information when used hand in hand with other drought indicators
May explain some illogical results of other indicators
Needs to be tested together with other indicators
Nevertheless, very useful indicator of spring floods