Preprints
https://doi.org/10.5194/egusphere-2024-2695
https://doi.org/10.5194/egusphere-2024-2695
20 Sep 2024
 | 20 Sep 2024
Status: this preprint is open for discussion.

Increasing water stress in Chile evidenced by novel datasets of water availability, land use and water use

Juan Pablo Boisier, Camila Alvarez-Garreton, Rodrigo Marinao, and Mauricio Galleguillos

Abstract. Many regions in Chile experienced an unprecedented drought from 2010 to 2022, driven by climate change and natural variability. This so-called megadrought led to severe water scarcity, causing conflicts and exposing issues in Chilean water regulations. Water-intensive agriculture in areas with limited water availability has worsened these problems, raising questions about the contributions of water extraction and climate on high water stress levels.

In this study, we evaluate water stress in Chile over the long term, from the mid-20th century to the end of the 21st century, under various climate and socio-economic scenarios. To this end, novel datasets of water availability, land use and water use were developed. Using these, we calculated the Water Stress Index (WSI) for all major basins in the country and assessed the impact of increasing water use and climate change on water stress over different time periods. Results show that most basins in semi-arid regions experienced high to extreme water stress (WSI > 40 % and WSI > 70 %, respectively) during the megadrought, mainly due to reduced water availability, but worsened by high water demand. Over time, increasing water stress in central Chile is primarily linked to rising water consumption, with a smaller contribution from water availability changes, leading to consistently high water stress levels (1990–2020 average) in several basins from Santiago northward. Under an adverse climate scenario (SSP3-7.0), megadrought-like conditions could become permanent by the end of the 21st century, with a projected 30 % drop in precipitation, resulting in high to extreme water stress in most basins in central Chile. We argue that using the WSI to assess one of the several aspects of water security offers a valuable strategy for adaptation plans. If public policy agrees on establishing quantifiable water security goals based on metrics like the WSI, different pathways of water use combined with alternative water sources can be evaluated to achieve them.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Juan Pablo Boisier, Camila Alvarez-Garreton, Rodrigo Marinao, and Mauricio Galleguillos

Status: open (until 15 Nov 2024)

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Juan Pablo Boisier, Camila Alvarez-Garreton, Rodrigo Marinao, and Mauricio Galleguillos
Juan Pablo Boisier, Camila Alvarez-Garreton, Rodrigo Marinao, and Mauricio Galleguillos

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Short summary

Our study examines water stress in Chile from mid-20th century to the end of the 21st century, using novel datasets on water availability, land use, and water use. We compute a water stress index for all basins in Chile and show that rising water use significantly contributes to water stress. We also show that a drier future is expected in central Chile and that the water stress index can be used as a tool for designing adaptation strategies.