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Preprints
https://doi.org/10.5194/egusphere-2024-2370
https://doi.org/10.5194/egusphere-2024-2370
02 Aug 2024
 | 02 Aug 2024

Assessing the different components of the water balance of Lake Titicaca

Nilo Lima-Quispe, Denis Ruelland, Antoine Rabatel, Waldo Lavado-Casimiro, and Thomas Condom

Abstract. This study estimates the water balance of a poorly-gauged large lake using an integrated modeling framework that accounts for natural hydrologic processes and net irrigation consumption. The modeling framework was tested on Lake Titicaca, located in the Altiplano of the Central Andes of South America. We used a conceptual approach based on the Water Evaluation and Planning System (WEAP) platform at a daily time step for the period 1982–2016, considering the following terms of the water balance: upstream inflows, direct precipitation and evaporation over the lake, and downstream outflows. To estimate upstream inflows, we evaluated the impact of snow and ice processes and net irrigation withdrawals on predicted streamflow and lake water levels. We also evaluated the role of heat storage change in evaporation from the lake. The results showed that the proposed modeling framework makes it possible to simulate lake water levels ranging from 3,808 to 3,812 m a.s.l. with good accuracy (RMSE = 0.32 m d-1) under a wide range of long-term hydroclimatic conditions. The estimated water balance of Lake Titicaca shows that upstream inflows account for 56 % (958 mm yr-1) and direct precipitation over the lake for 44 % (744 mm yr-1) of the total inflows, while 93 % (1,616 mm yr-1) of total outflows are due to evaporation and the remaining 7 % (121 mm yr-1) to downstream outflows. The water balance closure has an error of -15 mm yr-1. At the scale of the Lake Titicaca catchment, snow and ice processes, and net irrigation withdrawals had minimal impact on predicted upstream inflow. Thus, Lake Titicaca is primarily driven by variations in precipitation and high evaporation rates. The proposed modeling framework could be replicated in other poorly-gauged large lakes, as we demonstrate that a simple representation of natural hydrologic processes and irrigation enables accurate simulation of water levels.

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.
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Journal article(s) based on this preprint

04 Feb 2025
Modeling Lake Titicaca's water balance: the dominant roles of precipitation and evaporation
Nilo Lima-Quispe, Denis Ruelland, Antoine Rabatel, Waldo Lavado-Casimiro, and Thomas Condom
Hydrol. Earth Syst. Sci., 29, 655–682, https://doi.org/10.5194/hess-29-655-2025,https://doi.org/10.5194/hess-29-655-2025, 2025
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This study estimated the water balance of Lake Titicaca using an integrated modeling framework...
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