Browsing by Autor "Santini, William"

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Comment on egusphere-2025-4101
(2025) Santini, William; Delort-Ylla, Alexandre; Martinez, Jean Michel; Lavado-Casimiro, Waldo; Camenen, Benoît; Le Coz, Jérôme; Roussillon, Joana; Pérez Arévalo, Jhonathan Junior; Molina-Carpio, Jorge
<strong class="journal-contentHeaderColor">Abstract.</strong> Since the early 1970s, the Amazon basin has experienced growing local and global changes, potentially reaching a climatic tipping point in the coming decades. However, due to cost constraints and limited access, conventional hydrological networks in the basin struggle to provide the spatial resolution and temporal extent required for accurate quantification of water and sediment budgets, which are essential for understanding biogeochemical cycles. Focusing on the Ucayali River, a major Amazonian foreland tributary, this study provides the first long-term hydro-sediment balances in this region at sub-basin scale, distinguishing fine sediments from sand loads (37 years for water and sands, 20 years for fine sediments). It is achieved by the integration of remote sensing and hydrological-hydraulic modelling using a modified SWAT model, SWAT-Amazon. A new hydraulic module for water routing was implemented in SWAT-Amazon to suit the Amazon diffusive flood wave, representing floodplains as reservoirs. Fine sediment loads were estimated using satellite-derived concentrations and simulated discharges, while suspended sand loads were simulated within SWAT-Amazon. Results indicate that the Andean Ucayali River exports 455 10⁶ t yr⁻¹ of suspended sediment (40 % sand). As the floodplain traps 36 % of the Andean sediments (65 % sand), mostly by tectonic subsidence, the Ucayali delivers 290 10⁶ t yr⁻¹ of total suspended sediment to the Amazon River, 26 % as sand. Floodplain recycling plays a crucial role as a secondary sediment source (22 % of the Ucayali load), with a water storage that peaks at 19.1 km³ in March (38 % of discharge). A previously undocumented sand sedimentation process is identified during the flooding period, capturing 14 % of the sand flux at peak discharge and thus decorrelating sediment transport from water discharge. No significant long-term trends in flood duration, discharge, or sediment fluxes were detected, suggesting contrasted evolution patterns of the precipitations in the basin due to its particular position in the Amazon Basin. This study emphasizes the need to rethink hydrological network management with robust and long-term conventional data at ‘super’ stations to support the calibration of remote sensing and modelling at ‘virtual’ stations. Extending this approach to other Amazonian basins could significantly enhance hydro-sediment and biogeochemical cycle research in large river systems. Additionally, it highlights the importance of regionally focused over large-scale assessments, which often carry high uncertainties and may mislead mitigation strategies.
Comments on egusphere-2025-4101
(2025) Santini, William; Delort-Ylla, Alexandre; Martinez, Jean Michel; Lavado-Casimiro, Waldo; Camenen, Benoît; Le Coz, Jérôme; Roussillon, Joana; Pérez Arévalo, Jhonathan Junior; Molina-Carpio, Jorge
<strong class="journal-contentHeaderColor">Abstract.</strong> Since the early 1970s, the Amazon basin has experienced growing local and global changes, potentially reaching a climatic tipping point in the coming decades. However, due to cost constraints and limited access, conventional hydrological networks in the basin struggle to provide the spatial resolution and temporal extent required for accurate quantification of water and sediment budgets, which are essential for understanding biogeochemical cycles. Focusing on the Ucayali River, a major Amazonian foreland tributary, this study provides the first long-term hydro-sediment balances in this region at sub-basin scale, distinguishing fine sediments from sand loads (37 years for water and sands, 20 years for fine sediments). It is achieved by the integration of remote sensing and hydrological-hydraulic modelling using a modified SWAT model, SWAT-Amazon. A new hydraulic module for water routing was implemented in SWAT-Amazon to suit the Amazon diffusive flood wave, representing floodplains as reservoirs. Fine sediment loads were estimated using satellite-derived concentrations and simulated discharges, while suspended sand loads were simulated within SWAT-Amazon. Results indicate that the Andean Ucayali River exports 455 10⁶ t yr⁻¹ of suspended sediment (40 % sand). As the floodplain traps 36 % of the Andean sediments (65 % sand), mostly by tectonic subsidence, the Ucayali delivers 290 10⁶ t yr⁻¹ of total suspended sediment to the Amazon River, 26 % as sand. Floodplain recycling plays a crucial role as a secondary sediment source (22 % of the Ucayali load), with a water storage that peaks at 19.1 km³ in March (38 % of discharge). A previously undocumented sand sedimentation process is identified during the flooding period, capturing 14 % of the sand flux at peak discharge and thus decorrelating sediment transport from water discharge. No significant long-term trends in flood duration, discharge, or sediment fluxes were detected, suggesting contrasted evolution patterns of the precipitations in the basin due to its particular position in the Amazon Basin. This study emphasizes the need to rethink hydrological network management with robust and long-term conventional data at ‘super’ stations to support the calibration of remote sensing and modelling at ‘virtual’ stations. Extending this approach to other Amazonian basins could significantly enhance hydro-sediment and biogeochemical cycle research in large river systems. Additionally, it highlights the importance of regionally focused over large-scale assessments, which often carry high uncertainties and may mislead mitigation strategies.
Monitoreo hidrológico espacial de los ríos amazónicos para un manejo sostenible de los recursos hídricos
(Facultad de Ingenieria, 2025) Gutierrez Arosqueta, Rodrigo; Santini, William
En Bolivia la falta de información hidrométrica en general se debe a la baja accesibilidad en muchas localidades y/o la ausencia de carreteras de conexión como ser en la región amazónica. Ante la falta de información hidrométrica, la presente investigación busca la generación de información hidrométrica en la Amazonía Boliviana a través del monitoreo que realizan satélites espaciales a los cuerpos de agua para brindar mayor información de niveles de agua los cuales son sumamente importantes para el estudio de obras hidráulicas y el desarrollo del país. Se plantea una metodología la cual permita al usuario utilizar datos de altimetría satelital para la obtención de series temporales de niveles de agua. Se utilizó información de los satélites Jason 2, Jason 3, Sentinel 6A, Sentinel 3A, Sentinel 3B, SWOT para la generación de Estaciones Virtuales Hidrométricas en la Amazonía Boliviana. Se desarrolló la aplicación ALTANA (Altimetry - Analysis) en lenguaje R – Shiny en el marco del proyecto WiSSkHy desarrollado por HyBAm - IRD (Servicio de Observación, Hidrogeoquímica de la Cuenca del Amazonas – Institut de Recherche pour le Développement) en el Instituto de Hidráulica e Hidrología de la Universidad Mayor de San Andrés, el cual busca facilitar el trabajo de recopilación, procesamiento y análisis de la información. Así también, se utilizaron herramientas ya existentes como VALS que fue desarrollado por el IRD para el análisis de información altimétrica satelital.