Abstract
Climate change very likely impacts future hydrological drought characteristics across the world.
Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics
on a global scale using an alternative drought identification approach that considers adaptation to future
changes in hydrological regime. The global hydrological model PCR-GLOBWB was used to simulate daily discharge
at 0.5 globally for 1971–2099. The model was forced with CMIP5 climate projections taken from five
global circulation models (GCMs) and four emission scenarios (representative concentration pathways, RCPs),
from the Inter-Sectoral Impact Model Intercomparison Project.
Drought events occur when discharge is below a threshold. The conventional variable threshold (VTM) was
calculated by deriving the threshold from the period 1971–2000. The transient variable threshold (VTMt) is a
non-stationary approach, where the threshold is based on the discharge values of the previous 30 years implying
the threshold to vary every year during the 21st century. The VTMt adjusts to gradual changes in the hydrological
regime as response to climate change.
Results show a significant negative trend in the low flow regime over the 21st century for large parts of South
America, southern Africa, Australia and the Mediterranean. In 40–52% of the world reduced low flows are
projected, while increased low flows are found in the snow-dominated climates.
In 27% of the global area both the drought duration and the deficit volume are expected to increase when
applying the VTMt. However, this area will significantly increase to 62% when the VTM is applied. The mean
global area in drought, with the VTMt, remains rather constant (11.7 to 13.4 %), compared to the substantial
increase when the VTM is applied (11.7 to 20 %).
The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological
regime has a substantial influence on future hydrological drought characteristics.
Here, we quantify the impact of climate change on future low flows and associated hydrological drought characteristics
on a global scale using an alternative drought identification approach that considers adaptation to future
changes in hydrological regime. The global hydrological model PCR-GLOBWB was used to simulate daily discharge
at 0.5 globally for 1971–2099. The model was forced with CMIP5 climate projections taken from five
global circulation models (GCMs) and four emission scenarios (representative concentration pathways, RCPs),
from the Inter-Sectoral Impact Model Intercomparison Project.
Drought events occur when discharge is below a threshold. The conventional variable threshold (VTM) was
calculated by deriving the threshold from the period 1971–2000. The transient variable threshold (VTMt) is a
non-stationary approach, where the threshold is based on the discharge values of the previous 30 years implying
the threshold to vary every year during the 21st century. The VTMt adjusts to gradual changes in the hydrological
regime as response to climate change.
Results show a significant negative trend in the low flow regime over the 21st century for large parts of South
America, southern Africa, Australia and the Mediterranean. In 40–52% of the world reduced low flows are
projected, while increased low flows are found in the snow-dominated climates.
In 27% of the global area both the drought duration and the deficit volume are expected to increase when
applying the VTMt. However, this area will significantly increase to 62% when the VTM is applied. The mean
global area in drought, with the VTMt, remains rather constant (11.7 to 13.4 %), compared to the substantial
increase when the VTM is applied (11.7 to 20 %).
The study illustrates that an alternative drought identification that considers adaptation to an altered hydrological
regime has a substantial influence on future hydrological drought characteristics.
Original language | English |
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Pages (from-to) | 1-15 |
Number of pages | 15 |
Journal | Earth System Dynamics |
Volume | 6 |
DOIs | |
Publication status | Published - 2015 |