Abstract
Abstract. 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 &degC. 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.
Highlights
The impact of climate change on hydrological systems is receiving higher attention during the last decades due to its consequences on water resources, especially related to droughts and floods (Nijssen et al, 2001; Hirabayashi et al, 2008; Urrutia and Vuille, 2009; Dirmeyer et al, 2012)
This section reports on the change in the downscaled series for temperature and rainfall at the seven sites previously described, and the change in runoff for the Tomebamba in Monay (To Mo) and Matadero in Sayausi (Ma Sa) catchments
Within the analysis of the global climate model (GCM)-regional climate model (RCM) outputs, the RCMbased temperature changes are mainly driven by the largescale circulation models in which the RCM is nested
Summary
The impact of climate change on hydrological systems is receiving higher attention during the last decades due to its consequences on water resources, especially related to droughts and floods (Nijssen et al, 2001; Hirabayashi et al, 2008; Urrutia and Vuille, 2009; Dirmeyer et al, 2012). Hydrological processes at the land surface influence the natural environment at a range of spatial and temporal scales through their impacts on biological activity and water chemistry (Beldring et al, 2008). This is the case for the Paute River basin in Ecuador, where future climate change might severely impact hydrological and ecological conditions. The water availability is a concern (Ontaneda et al, 2002), due to changes in temperature and humidity and high variability in rainfall extreme events (Parry et al, 2007)
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