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L. Zaharia et al.
mate change/emission scenarios, without considering other influences such as water
uses and political or socio-economic impacts [1]. Therefore, the results projected by
the models should be considered with caution, given the associated limitations and
uncertainties.
On a global scale, there are many studies on possible future hydrological responses
to climate changes [e.g., 67–77]. At continental and regional/national level, numerous
studies have been carried out, mainly in Europe [64, 78–88], but also in US [89] and
Asia [90–92]. Several papers [93–96] investigated the potential effect of climate
change on river flow regimes in some large watersheds on different continents (e.g.,
Amazon, Rhine, Tagus, Niger, Blue Nil, Mississippi, Mackenzie, Yellow, Yangtze,
Lena, Darling).
At the global scale, according to [67], by 2100, the models project a general
increase of mean discharges with more than 10%. Some global patterns of change
in discharge regimes for 2100 may be distinguished, such as significant decreases
in streamflow for southern Europe, southern Australia, south and north of Africa
and southwestern South America. Consistent decreases for most African rivers,
the Murray and the Danube rivers, as well as slightly increases of discharges for
monsoon-influenced rivers are expected. In the sub-Arctic and Arctic regions runoff
increases and a phase-shift towards earlier peaks are projected by 2100. An increase
in the seasonality of river discharges was identified (both an increase of high flow
and a decrease of low flow) for about one-third of the global land surface area for
2071–2100 relative to the reference period 1971–2000 [68]. Most of the 21st climate
models used in [69] projected increases in average annual runoff by 2050 in Canada
and high latitudes of Eastern Europe and Siberia, and decreases in runoff in central
Europe, around the Mediterranean Sea, the Mashriq, central America and Brazil.
A study on impacts of climate change on European hydrology at 1.5, 2 and 3 °C
mean global warming above preindustrial level showed that there are clear changes
in local impacts on mean, low and high runoff. Important increases in streamflow will
affect the Scandinavian countries and northern Poland. Decreases in mean annual
runoff were projected only in Portugal at 1.5 °C warming, but at 3 °C warming, the
runoff will decrease on the entire Iberian coast, the Balkan Coast and parts of the
French coast [86].
Of high interest is the assessment of future changes in the characteristics of the
hydrological extreme events (severity and frequency). Therefore, many studies were
devoted to these phenomena. Thus, several papers focused on the assessment of
future floods and high flow [e.g., 64, 81, 88, 97], while other studies investigated
the projections of future low flow and hydrological droughts [70, 71, 73, 74, 83, 87,
etc.]. Some authors investigated both hydrological extremes [e.g., 68, 84, 86, 93].
At a global scale, a study on impacts of climate change on river flood risk shows
that in 2050 the current 100-year flood would occur at least twice as frequently across
40% of the globe [69]. At 4 °C global warming, countries representing more than
70% of the total population will face increases in flood risk more than 500% [77].
The largest increase in the flood risk will be in Asia, Europe and U.S.A.
In Europe, it was found that, on average, flood peaks with return periods above
100 years are projected to double in frequency within 3 decades [97]. According
L. Zaharia et al.
mate change/emission scenarios, without considering other influences such as water
uses and political or socio-economic impacts [1]. Therefore, the results projected by
the models should be considered with caution, given the associated limitations and
uncertainties.
On a global scale, there are many studies on possible future hydrological responses
to climate changes [e.g., 67–77]. At continental and regional/national level, numerous
studies have been carried out, mainly in Europe [64, 78–88], but also in US [89] and
Asia [90–92]. Several papers [93–96] investigated the potential effect of climate
change on river flow regimes in some large watersheds on different continents (e.g.,
Amazon, Rhine, Tagus, Niger, Blue Nil, Mississippi, Mackenzie, Yellow, Yangtze,
Lena, Darling).
At the global scale, according to [67], by 2100, the models project a general
increase of mean discharges with more than 10%. Some global patterns of change
in discharge regimes for 2100 may be distinguished, such as significant decreases
in streamflow for southern Europe, southern Australia, south and north of Africa
and southwestern South America. Consistent decreases for most African rivers,
the Murray and the Danube rivers, as well as slightly increases of discharges for
monsoon-influenced rivers are expected. In the sub-Arctic and Arctic regions runoff
increases and a phase-shift towards earlier peaks are projected by 2100. An increase
in the seasonality of river discharges was identified (both an increase of high flow
and a decrease of low flow) for about one-third of the global land surface area for
2071–2100 relative to the reference period 1971–2000 [68]. Most of the 21st climate
models used in [69] projected increases in average annual runoff by 2050 in Canada
and high latitudes of Eastern Europe and Siberia, and decreases in runoff in central
Europe, around the Mediterranean Sea, the Mashriq, central America and Brazil.
A study on impacts of climate change on European hydrology at 1.5, 2 and 3 °C
mean global warming above preindustrial level showed that there are clear changes
in local impacts on mean, low and high runoff. Important increases in streamflow will
affect the Scandinavian countries and northern Poland. Decreases in mean annual
runoff were projected only in Portugal at 1.5 °C warming, but at 3 °C warming, the
runoff will decrease on the entire Iberian coast, the Balkan Coast and parts of the
French coast [86].
Of high interest is the assessment of future changes in the characteristics of the
hydrological extreme events (severity and frequency). Therefore, many studies were
devoted to these phenomena. Thus, several papers focused on the assessment of
future floods and high flow [e.g., 64, 81, 88, 97], while other studies investigated
the projections of future low flow and hydrological droughts [70, 71, 73, 74, 83, 87,
etc.]. Some authors investigated both hydrological extremes [e.g., 68, 84, 86, 93].
At a global scale, a study on impacts of climate change on river flood risk shows
that in 2050 the current 100-year flood would occur at least twice as frequently across
40% of the globe [69]. At 4 °C global warming, countries representing more than
70% of the total population will face increases in flood risk more than 500% [77].
The largest increase in the flood risk will be in Asia, Europe and U.S.A.
In Europe, it was found that, on average, flood peaks with return periods above
100 years are projected to double in frequency within 3 decades [97]. According