Evaluation of the Impact of Climate Change on Runoff Generation in an Andean Glacier Watershed

Abstract

Excluding Antarctica and Greenland, 3.8% of the world’s glacier area is concentrated in Chile. The country has been strongly affected by the mega drought, which affects the south-central area and has produced an increase in dependence on water resources from snow and glacier melting in dry periods. Recent climate change has led to an elevation of the zero-degree isotherm, a decrease in solid-state precipitation amounts and an accelerated loss of glacier and snow storage in the Chilean Andes. This situation calls for a better understanding of future water discharge in Andean headwater catchments in order to improve water resources management in glacier-fed populated areas. The present study uses hydrological modeling to characterize the hydrological processes occurring in a glacio-nival watershed of the central Andes and to examine the impact of different climate change scenarios on discharge. The study site is the upper sub-watershed of the Tinguiririca River (area: 141 km2), of which nearly 20% is covered by Universidad Glacier. The semi-distributed Snowmelt Runoff Model + Glacier (SRM+G) was forced with local meteorological data to simulate catchment runoff. The model was calibrated on even years and validated on odd years during the 2008–2014 period and found to correctly reproduce daily runoff. The model was then forced with downscaled ensemble projected precipitation and temperature series under the RCP 4.5 and RCP 8.5 scenarios, and the glacier adjusted using a volume-area scaling relationship. The results obtained for 2050 indicate a decrease in mean annual discharge (MAD) of 18.1% for the lowest emission scenario and 43.3% for the most pessimistic emission scenario, while for 2100 the MAD decreases by 31.4 and 54.2%, respectively, for each emission scenario. Results show that decreasing precipitation lead to reduced rainfall and snowmelt contributions to discharge. Glacier melt thus partly buffers the drying climate trend, but our results show that the peak water occurs near 2040, after which glacier depletion leads to reducing discharge, threatening the long-term water resource availability in this region.

Quantify Runoff Reduction in the Zhang River Due to Water Diversion for Irrigation

“…Current research on the attribution of runoff change and water consumption change in the catchment area has mainly focused on the following aspects: attribution identification of different influencing factors, including an attribution analysis of the dominant factors such as the climate [44,45], the underlying surface [46], and human activities [47] and an analysis of the impact of synergies between different elements. Besides an attribution analysis of the influencing factors of runoff change, the main causes of runoff change affected by different factors and the allocation of water resources after runoff change should also be the focus of researchers, especially in areas where human activities account for a large proportion.…”

Modelling Snowmelt Runoff from Tropical Andean Glaciers under Climate Change Scenarios in the Santa River Sub-Basin (Peru)

“…The SRM was used, which has been applied in many river basins analysed under climate change scenarios [1,4,45,49]. The model requires large amounts of data to simulate runoff on a daily scale in catchments where snow and glacier melt dominate the runoff generation process [49].…”

“…The SRM was used, which has been applied in many river basins analysed under climate change scenarios [1,4,45,49]. The model requires large amounts of data to simulate runoff on a daily scale in catchments where snow and glacier melt dominate the runoff generation process [49]. In this study, it was necessary to use historical data on temperature, precipitation and SCA, which allowed for successful calibration and validation during the baseline period (2005)(2006)(2007)(2008)(2009).…”

“…Climate change has been shown to have a negative effect in high Andean areas by increasing the retreat of glaciers [49]. Air temperature has a significant influence on the energy balance, although not through sensible heat flux, but indirectly through rain-snow fluctuations [35].…”

AI‐based runoff simulation based on remote sensing observations: A case study of two river basins in the United States and Canada

“…The calculated recession flow rate is added to the daily inflow obtained from the snowmelt, which is used to create the daily discharge on the catchment based on the following relationship:where is the daily average discharge (m 3 /s); , , and are the daily average snowmelt, liquid precipitation, and glacier melt (cm/day), respectively; k is the recession coefficient (dimensionless); is the index of the current day; and and m are the index and the total number of elevation bands, respectively. The expression provides a conversion factor to gain the daily discharge units (m 3 /s) (Escanilla‐Minchel et al, 2020).…”