Climate changes of hydrometeorological and hydrological extremes in the Paute basin

Investigation was made on the climate change signal
for hydrometeorological and hydrological variables along
the Paute River basin, in the southern Ecuador Andes. An adjusted
quantile perturbation approach was used for climate
downscaling, and the impact of climate change on runoff
was studied for two nested catchments within the basin. The
analysis was done making use of long daily series of seven
representative rainfall and temperature sites along the study
area and considering climate change signals of global and
regional climate models for IPCC SRES scenarios A1B, A2
and B1. The determination of runoff was carried out using
a lumped conceptual rainfall-runoff model. The study found
that the range of changes in temperature is homogeneous for
almost the entire region with an average annual increase of
approximately +2.0 C. However, the warmest periods of the
year show lower changes than the colder periods. For rainfall,
downscaled results project increases in the mean annual
rainfall depth and the extreme daily rainfall intensities along
the basin for all sites and all scenarios. Higher changes in
extreme rainfall intensities are for the wetter region. These
lead to changes in catchment runoff flows, with increasing
high peak flows and decreasing low peak flows. The changes
in high peak flows are related to the changes in rainfall extremes,
whereas the decreases in the low peak flows are due
to the increase in temperature and potential evapotranspiration
together with the reduction in the number of wet days.

Trefwoorden:Climate changes, hydrometeorological and hydrological extremes, Paute basin, Ecuadorean Andes