Abstract
The study on high flows with a conceptual hydrological model leads to the following conclusions for
about 1500 randomly selected land points across the world that have an intermediate soil water supply
capacity and an intermediary responding groundwater system:
· the probability distributions of Q10 (flow that is equalled or exceeded 10% of
... read more
the time) for the three
GCMs (ECHAM. CNRM, IPSL) are very similar for the control period (1971-2000), irrespective of the
Köppen-Geiger climate type, which means that the downscaled, bias-corrected climate data from the
climate models for the last part of the 20th century only slightly deviate;
· median Q10s derived from the GCMs for the CTRL period differ at least tens of per cent from the
Q10 obtained when using WFD as input for the hydrological model (i.e. about 30-60%). The
differences for the arid and polar (B- and E-) climates are higher because of the low discharge, and
for the B-climate also due to overestimation of the high Q10s (about 100% or more);
· the impact of climate change (median of Q10 as metric) is projected to increase over the 21st century
according to all three GCMs (A2 scenario) for the C-, D- and E-climates. This is also expected for the
A- and B-climates according to ECHAM and CNRM. IPSL provides for these two Köppen-Geiger
major climate regions a more diffuse projection;
· the projected increase of the median Q10 because of climate change (A2 scenario) varies between
about 5 and 20% for the near future (2021-2050), irrespective of the Köppen-Geiger major climate
region and the GCM. The only exception is IPSL that expects a decrease of the Q10 by about 5% for
the equatorial climate;
· the projected increase of the median Q10 by the end of the 21st century (2071-2100) varies between
about 15 and 60%, ), irrespective of the Köppen-Geiger major climate region and the GCM. The only
exception again is IPSL. This model expects a decrease of the median Q10 by about 2-10% for the
equatorial and arid climates (A- and B-climates;
· difference between the median Q10 derived from the hydrological model forced with re-analysis data
(WFD) and the same model forced with the down-scaled, bias corrected climate output from three
climate models for the control period (1971-2000) clearly exceeds the differences found by climate
change in the 21st century.
The analysis of high flows as obtained with the rather simple hydrological model in this study should be
extended with:
· the outcome from the GCMs for the B1 scenario;
· an analysis at the global scale of the outcome from the suite of large-scale models that have been
run within the WATCH project similar to the study of Miller et al. (2011) for Europe.
show less
