Impact of climate change on future discharges from a high Andean basin in Peru to 2100

Abstract

The objective of this research was to analyze the impact of climate change on the behavior of monthly discharges in the Anya basin, a tributary of the Mantaro, Junin, at 2100, with the SWAT (Soil and Water Assessment Tool) model. Daily gridded data on precipitation and temperatures were obtained from PISCO (Peruvian Interpolated data of the SENAMHI’s Climatological and Hydrological Observations) between 1981 and 2015 and average monthly flows measured at the Anya hydrometric station. For the analysis of the space-time effect of climate change on temperature and precipitation and its influence on basin runoff, five global climate models (ACCES1.0, bcc_csm1, BNU_ESM, CMCC_CM and GISS_E2) were used in two emission scenarios (RCP 4.5 and 8.5). The simulation was carried out for the period 2070-2100, considering 1980-2010 as the base period. The model worked satisfactorily with the statistical values of Nash-Sutcliffe (NSE), PBIAS and coefficient of determination (R2). In the basin, the average results show an increase in precipitation (between 4.63 and 8.14 %) and temperature (from 2.3 to 4.2 °C), in RCP 4.5 and 8.5 scenarios by 2100. Likewise, there would be an increase in flows in comparison with the base period, obtaining that, on average, the flow in the basin would increase by 2.4 and 12.6 % in the RCP 4.5 and 8.5 scenarios, respectively. It is concluded that the increase in temperature and precipitation will influence a greater runoff and risk of flooding in the cultivation areas in the basin.