Current and future water balance for coupled human-natural systems - Insights from a glacierized catchment in Peru

Study region: Santa River basin, Peru. Study focus: In the Andes of Peru, climate change and socio-economic development are expected to jeopardize future water availability. However, little is known about the interplay of multiple climatic and non-climatic stressors and related processes driving water resource changes. We developed an integrated model that analyzes different trajectories of water availability including hydro-climatic (water supply) and socio-economic (water demand) variables with consistent multi-descriptor future scenarios until 2050. New hydrological insights for the region: At the lower-basin outflow of Condorcerro, mean annual water availability is projected to increase by 10% +/- 12% by 2050. This gain is mainly driven by an increase in annual precipitation amounts of about 14% (RCP2.6) and 18% (RCP8.5), respectively, which was computed using a global climate multi-model ensemble. In contrast, mean dry season water availability is projected to substantially decrease by 33% and 36% (+/- 24%) by 2050, for RCP2.6 and RCP8.5, respectively. This decline is driven by a combination of diminishing glacier discharge and increasing water demand both of which adopt a major role in the absence of considerable precipitation inputs. These seasonal differences highlight the need to adequately consider spatiotemporal scales within multi-scenario water balance models to support local decision-making. Our results elucidate the need for improvements in water management and infrastructure to counteract diminishing dry-season water availability and to reduce future risks of water scarcity.

Automated summary

This study focuses on water resource changes in the Santa River basin in Peru. By developing an integrated model, the researchers analyze different trajectories of water availability in the future. The results show that mean annual water availability is projected to increase, but there will be a substantial decrease in dry season water availability. This highlights the importance of considering spatiotemporal scales in multi-scenario water balance models to support local decision-making, and emphasizes the need for improvements in water management and infrastructure.