Analysis of vertical flow velocity and suspended sediment concentration profiles in Tumbes River during El Niño and La Niña events

Dampier Mendoza Sulcaray R.; Luis Campaña Toro R.; Natalia Armijos Cárdenas E.; Byron Morera Julca S. · Proceedings of the LACCEI international Multi-conference for Engineering, Education and Technology (2024) · DOI: 10.18687/laccei2024.1.1.1859

Resumen

The Tumbes region, situated in northern Peru, is impacted by the climatic phenomena of El Niño and La Niña. El Niño brings about intense precipitation, resulting in high water flows and sediment generation. Conversely, La Niña leads to precipitation deficits, resulting in lower liquid flows and sediment loads compared to El Niño. The objective of this study is to analyze the vertical flow velocity profiles and suspended sediment concentration measured at the El Tigre hydrometric station on the Tumbes River, located 50 km upstream from the Pacific Ocean estuary, during flood periods in the El Niño events of 2017 and the La Niña events of 2018. Vertical flow velocity profiles, measured using a Doppler effect current meter, were modeled by applying the theoretical velocity distribution of the log-wake type. Parameters such as shear velocity, distance from the bed where the flow profile velocity theoretically becomes zero, and the wake parameter were adjusted. Vertical suspended sediment concentration profiles were modeled using the theoretical distribution resulting from the parabolic-linear distribution of the fluid mixing coefficient. Parameters including mean diameter of suspended sediments and reference suspended sediment concentration near the bed were adjusted. The study concluded that the vertical flow velocity profiles and suspended sediment concentration profiles recorded during the El Niño event of 2017 and La Niña event of 2018 reasonably matched the theoretical velocity distribution of the log-wake type and the theoretical concentration distribution of suspended sediments resulting from the parabolic-linear distribution of the fluid mixing coefficient. Using the adjusted models, it was estimated that the mean sizes of suspended sediments calculated for the El Niño event of 2017 (62 to 132 µm) were approximately 2 times those calculated for La Niña of 2018 (25 to 67 µm), and that the reference concentrations of suspended sediment at the bed level calculated for the El Niño event of 2017 (254 to 1766 mg/l) were approximately 7 times those calculated for La Niña of 2018 (95 to 250 mg/l).

Instituciones: Universidad Nacional de Ingeniería