Climate change impacts and vulnerability in Europe 2016

Climate change impacts on environmental systems
Map 4.7
Model-based estimate of past change in annual river flows
-30°
-20°
-10°
0°
10°
20°
30°
40°
50°
60°
70°
Model–based estimate of past
change in annual river flows
< 75 % of models agree
on sign of trend
Percentage
60°
100
80
60
50°
40
20
0
50°
– 20
– 40
– 60
40°
– 80
– 100
40°
Outside model coverage
Outside coverage
0 500 1000 1500 km
0°
10°
20°
30°
40°
Note:
This map shows the ensemble mean trend in annual run-off from 1963 to 2000. 'x' denotes grid cells where less than three-quarters of
the hydrological models agree on the direction of the trend.
Source: Adapted from Stahl et al., 2012.
Projections
Annual river flows are projected to decrease in
southern and south-eastern Europe and increase in
northern and north-eastern Europe (Rojas et al., 2012;
Alfieri, Burek et al., 2015). Changes are projected in
the seasonality of river flows, with large differences
across Europe. For most parts of Europe, the peak
of the average daily flow at the end of the 21st
century is projected to occur earlier in the year
than currently (van Vliet et al., 2013; Forzieri et al.,
2014). In snow‐dominated regions, such as the Alps,
Scandinavia and parts of the Baltic, the reduction
in winter retention as snow, earlier snowmelt and,
in some cases, reduced summer precipitation are
projected to lead to increases in river flows in winter
and reductions in summer (Alfieri, Burek et al., 2015).
Reductions of flow can be exacerbated by water
abstractions, especially in summer when consumption
is highest and input is typically low. These changes
result in a further decrease of water availability in
summer (see Figure 4.11) (Forzieri et al., 2014).
138 Climate change, impacts and vulnerability in Europe 2016 | An indicator-based report