loading page

Streamflow extremes alter air-water relationships in South American river-floodplain systems of the Uruguay River Basin
  • +4
  • Christine Lucas,
  • Leticia de Los Santos,
  • Juan Badagian,
  • Pablo Gamazo,
  • Marcelo Crossa,
  • Elias Brum,
  • Luis Morales-Marin
Christine Lucas
Universidad de la Republica Uruguay Facultad de Ciencias

Corresponding Author:[email protected]

Author Profile
Leticia de Los Santos
Universidad de la Republica Uruguay - Regional Norte Sede Salto
Author Profile
Juan Badagian
Universidad de la Republica Uruguay - Regional Norte Sede Salto
Author Profile
Pablo Gamazo
Universidad de la Republica Uruguay - Regional Norte Sede Salto
Author Profile
Marcelo Crossa
Czech Academy of Sciences Czech Centre for Phenogenomics
Author Profile
Elias Brum
Direccion Nacional de Medio Ambiente
Author Profile
Luis Morales-Marin
Universidad Nacional de Colombia Facultad de Ingenieria
Author Profile

Abstract

Extreme hydroclimate events affect the thermal regimes of freshwater systems. In a four-year period spanning periods of flooding and severe drought in Southeastern South America (2019-2023), we monitored temperature variability in streams and floodplain lakes in an undammed tributary of the Lower Uruguay River, using Onset HOBO dataloggers and modeled daily streamflow (Q). We compare the performance of linear and nonlinear regression and generalized additive models (GAM) to evaluate how air temperature (T air) variability affects water temperature (T water) at daily, weekly and monthly time scales and under different Q percentile ranges. Mean daily temperatures ranged from 6.4ºC to 30.2ºC with daily maxima coinciding with record highs >40 ºC in T air and record low streamflow in summer months. Daily and weekly air-water relationships for rivers, streams and lakes were best fit by nonlinear sinusoidal models (Nash Sutcliffe Error - NSE ≥ 0.68). Extremely low-flow periods (<10% Q) showed a linear relationship to T air, while high-flow periods (>90%) showed a nonlinear sinusoidal air-water relationship. Moreover, high-flow events showed weaker T air-T water model perforamce than moderate to low flow periods. Preliminary comparisons between basin land-cover and T water suggest that forest cover favors lower T min. This study fills a geographical gap in thermal regime data in freshwater ecosystems in South America and suggests that extreme hydroclimate events have important implications for the thermal behavior of freshwater systems.
13 Nov 2023Submitted to River Research and Applications
15 Nov 2023Submission Checks Completed
15 Nov 2023Assigned to Editor
20 Nov 2023Review(s) Completed, Editorial Evaluation Pending
25 Jan 2024Editorial Decision: Revise Major
16 Apr 2024Review(s) Completed, Editorial Evaluation Pending
23 Apr 2024Editorial Decision: Revise Major
26 Jun 20242nd Revision Received
27 Jun 2024Submission Checks Completed
27 Jun 2024Assigned to Editor
01 Jul 2024Reviewer(s) Assigned
11 Jul 2024Review(s) Completed, Editorial Evaluation Pending
10 Oct 2024Editorial Decision: Revise Major