Stable water isotopic composition and evaporation to inflow ratios for high-mountain tropical Ecuadorian lakes

• Published in: Hydrological sciences journal 2024-08, Vol.69 (11), p.1523-1538
• Main Authors: Lyon, Steve W., Hickman, Scott, Mosquera, Pablo V., Vázquez, Raúl F., Hampel, Henrietta
• Format: Article
• Language: English
• Subjects: Cajas National Park; Chemical composition; Composition; Evaporation; evaporation to inflow ratios; high-mountain tropical lakes; Inflow; Isotope composition; Isotopes; Mountains; National parks; Seasonal variability; Seasonal variation; Seasonal variations; Stable isotopes; stable isotopes of water; Tropical lakes; Water depth; Water inflow; Water levels
• ISSN: 0262-6667; 2150-3435
• DOI: 10.1080/02626667.2024.2377354

In this study, we explore the utility of stable isotopes of water (δ 2 H and δ 18 O) as integrative proxies for evaporative condition in high-mountain tropical lakes using a set of small Ecuadorian lakes in the Cajas National Park. Specifically, we (1) characterize the variability of stable water isotopic composition across several lakes of varying size and depth and (2) determine the evaporation as a fraction of inflow using stable isotopes of water for these lakes. We have used the Hydrocalculator tool for estimation of the evaporation to inflow (E/I) ratio. Results indicated that larger lakes have lower seasonal variability in isotopic composition across their depth compared with the smaller lakes. Further, there was clear seasonal variation across the monthly E/I ratios estimated in several lakes, indicating that evaporation likely plays some (albeit limited) role in the water level variability experienced within a year.