Resumo

LAGOS-ZUNIGA, Miguel Ángel  e  VARGAS-MESA, Ximena. Potential Influences of Climate Change on Pluvial Floods in an Andean Watershed. Tecnol. cienc. agua [online]. 2014, vol.5, n.2, pp.19-38. ISSN 2007-2422.

In studies of floods in basins with a snow regime, the role of temperature has been found to be as important as precipitation to determine the magnitude of the floods, since it defines the contributing catchment area bounded by snow lines (H_LN). Therefore, the hypsometry of the basin is also relevant since it determines the percentage of additional catchment area resulting from small variations in H_LN. This study analyzes the effects of different combinations of snow line elevations and precipitation, different probabilities of exceedance, for pluvial floods with return periods of 1 000 and 10 000 years (T) in a Chilean Andean basin with a snow regime. The results obtained were compared with previous studies in which the contributing catchment area was taken as constant, finding a significant variation of up to 20% with respect to the mean peak flow of floods with T = 1 000 years. This suggests that future designs of large hydraulic works in basins with similar hydrological regimes should take into account these combinations. In addition, the possible effects of climate change, based on future scenarios A2 and B1 (2045-2065), on the magnitude of these floods were examined. In the study zone, an increase in the magnitude of daily precipitation is projected for T = 1 000 years, up to 70% on average, for scenario B1 and an average increase in temperature of +1.8 °C and +1.3 °C is projected for scenarios A2 and B1, respectively. This will lead to increases in peak flow and direct runoff volumes of up to 72 and 84%, respectively, for the period 2045 - 2065, variations that could exceed the confidence interval for extreme floods calculated for the historical period and result in the vulnerability of the dam located at the outlet of the study basin to floods under climate change scenarios.

Palavras-chave : climate change; contributing area; floods; mixed regime.

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