“Small variations in the climate conditions have remarkable effects. The results of HCILS can be used to assess a lake actual state, and they show what can be expected in the future.• The water balance and residence time in alpine lakes are very
sensitive to changes in air temperature and precipitation.
A temperature increase of 1.4 °C until 2050 produces reductions in lake water renewal of 12 to 23 % of the annual mean (summer change is much higher with partly > 81 %.
The superposition with only small decreases in precipitation (5 %) produces important reductions of lake water renewal up to more than 40 % annual mean, summer change is even higher with partly > 117 %).
Land use changes (p.e. reforestation) can increase significantly these water losses (future research demand).
Consequently the fill up time and mean residence time of lake water are increasing.
Small lakes with small catchment areas are more sensitive to climate change.
The mean residence time of lake water is not in accordance with the water renewal (or fill up) time of lakes.
Its work of the limnologists to interpret the impact of these changes on the ecological and quality conditions of lakes. ”