10 Hydrological Impacts of Climate Changes in Romania
327
The simulation of the annual maximum discharges in Cri¸ sul Alb River basin, for
the scenario S1 compared to S0 scenario, indicated, generally, a slight negative trend
in the upper part of the basin (of maximum −3%) and an increasing trend for the
lower part (of maximum 7%) while the scenario S2 indicated a significant increase
(of maximum 41%) on the entire watershed. Concerning the annual minimum discharges, the simulations indicated for scenario S1 compared to S0 scenario a decrease
of up to −8%, and for the scenario S2 an increase of maximum 7% on the entire
river basin [144].
A few studies investigated the hydrological alteration induced by climate change
in Mures , River basin, the largest catchment in the central part of Romania (Fig. 10.1).
Based on scenarios obtained from nine coupled runs of GCM-RCM model driven
by A1B socio-economic development scenario and using the SWIM hydrological
model, the hydrological response to climate change was simulated in the upper
part of the Mures , River basin (upstream Alba Iulia g.s.), for the reference period
(1971–2000) and two future periods (2021–2050 and 2071–2100) [173]. The projections indicated a deviation in median monthly discharges, as follows: increase
for the winter months for both future periods, and decrease for late spring, summer
and early autumn by the year 2100. Over half of the simulations projected a slight
increase in median and maximum values for the number of days with high flow,
but a more significant increase for the duration of flow events, indicating that it is
likely that drought events will become longer by the year [173]. These results are
generally consistent with [164], study that investigated the potential hydrological
impacts of changes in temperatures and precipitation in the entire Mures , River basin
(using the SRES A1B scenario), considering the same future periods (2021–2050
and 2071–2010), compared to the reference period 1961–1990. Based on the results
of climate projections (with ALADIN and REMO models), the simulations showed
that the annual streamflow will certainly decrease in the long run and early spring
snow melt could be more intensive, causing the increase of the river flow. The projections also indicated that the early summer floods might be less significant; summer
and autumn low flow extremes may occur more frequent, and severe water scarcity
may affect the lower sector of the Mures , River [164].
At national spatial scale, the changes induced by climate change on the mean
(monthly and annual) streamflow in 20 large basins (including 275 sections) were
investigated for the time horizon 2021–2050, by using the hydrological models WATBAL and CONSUL [174]. The simulations were performed considering two scenarios: Scenario 0, corresponding to the reference period 1971–2000, and Scenario 1,
in which the mean monthly discharges for the period 2021–2050 were estimated by
using simulations of climate change evolution performed within CLAVIER Project
(A1B scenario). The results indicated a general decline of the mean multiannual discharges (of maximum −38% in Vedea River basin), excepting the Somes , River basin
where an increase (of maximum 23%) was identified. Regarding the monthly mean
multiannual discharges, projections showed in most analyzed catchments significant
increases in the winter months (December, January, February) and sometimes in
March (i.e., in Mures , , Arges , and Siret watersheds) and pronounced decreases in late
summer and autumn (August–November) [174].
327
The simulation of the annual maximum discharges in Cri¸ sul Alb River basin, for
the scenario S1 compared to S0 scenario, indicated, generally, a slight negative trend
in the upper part of the basin (of maximum −3%) and an increasing trend for the
lower part (of maximum 7%) while the scenario S2 indicated a significant increase
(of maximum 41%) on the entire watershed. Concerning the annual minimum discharges, the simulations indicated for scenario S1 compared to S0 scenario a decrease
of up to −8%, and for the scenario S2 an increase of maximum 7% on the entire
river basin [144].
A few studies investigated the hydrological alteration induced by climate change
in Mures , River basin, the largest catchment in the central part of Romania (Fig. 10.1).
Based on scenarios obtained from nine coupled runs of GCM-RCM model driven
by A1B socio-economic development scenario and using the SWIM hydrological
model, the hydrological response to climate change was simulated in the upper
part of the Mures , River basin (upstream Alba Iulia g.s.), for the reference period
(1971–2000) and two future periods (2021–2050 and 2071–2100) [173]. The projections indicated a deviation in median monthly discharges, as follows: increase
for the winter months for both future periods, and decrease for late spring, summer
and early autumn by the year 2100. Over half of the simulations projected a slight
increase in median and maximum values for the number of days with high flow,
but a more significant increase for the duration of flow events, indicating that it is
likely that drought events will become longer by the year [173]. These results are
generally consistent with [164], study that investigated the potential hydrological
impacts of changes in temperatures and precipitation in the entire Mures , River basin
(using the SRES A1B scenario), considering the same future periods (2021–2050
and 2071–2010), compared to the reference period 1961–1990. Based on the results
of climate projections (with ALADIN and REMO models), the simulations showed
that the annual streamflow will certainly decrease in the long run and early spring
snow melt could be more intensive, causing the increase of the river flow. The projections also indicated that the early summer floods might be less significant; summer
and autumn low flow extremes may occur more frequent, and severe water scarcity
may affect the lower sector of the Mures , River [164].
At national spatial scale, the changes induced by climate change on the mean
(monthly and annual) streamflow in 20 large basins (including 275 sections) were
investigated for the time horizon 2021–2050, by using the hydrological models WATBAL and CONSUL [174]. The simulations were performed considering two scenarios: Scenario 0, corresponding to the reference period 1971–2000, and Scenario 1,
in which the mean monthly discharges for the period 2021–2050 were estimated by
using simulations of climate change evolution performed within CLAVIER Project
(A1B scenario). The results indicated a general decline of the mean multiannual discharges (of maximum −38% in Vedea River basin), excepting the Somes , River basin
where an increase (of maximum 23%) was identified. Regarding the monthly mean
multiannual discharges, projections showed in most analyzed catchments significant
increases in the winter months (December, January, February) and sometimes in
March (i.e., in Mures , , Arges , and Siret watersheds) and pronounced decreases in late
summer and autumn (August–November) [174].