Modelo para estimar la probabilidad de excedencia de caudales umbrales en la cuenca Río Salado
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Date
2023
Profesor/a Guía
Facultad/escuela
Idioma
es
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Publisher
Universidad Andrés Bello
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Abstract
Durante los días 24 al 26 de marzo de 2015, condiciones oceánicas y atmosféricas
inusuales produjeron lluvias con periodos de retorno muy altos con una duración de
aproximadamente 48 hrs sobre el desierto de Atacama, en el norte de Chile, una de las regiones
más áridas de la Tierra, lo que resultó en inundaciones catastróficas. La tormenta del 24 al 26 de
marzo de 2015 generó una crecida de caudal umbral de 997 m3
/s en la desembocadura del río
Salado, en la ciudad de Chañaral, se observó que esta crecida produjo profundidades máximas de
agua de más de 4,5 m, dejando gran cantidad de lodo en edificios y calles de la ciudad, esto generó
un gran daño material y pérdida de vidas humanas. Durante la fecha de ocurrencia de este episodio,
la cuenca del río Salado no disponía de estaciones de medición de caudales que permitieran
anticipar el caudal que se generaría en ese momento a la ciudad de Chañaral. Con las técnicas
actuales, es posible determinar con cierta precisión el pronóstico del volumen y duración de una
tormenta, pero no su distribución en el tiempo. Se propuso una herramienta para estimar la
probabilidad de excedencia de diferentes caudales umbrales, a partir del volumen de la
precipitación pronosticada y su duración. Se construyó un modelo ARMA para generar un conjunto
de hietogramas sintéticos, para precipitaciones de periodos de retorno de entre 50 y 10000 años,
con duraciones aleatorias de distribución uniforme entre 12 y 72 horas. Se construyó un modelo
semi-distribuido de la cuenca aportante a Chañaral, se utilizó el método del número de curva para
estimar la precipitación efectiva, el método del hidrograma unitario sintético para estimar el caudal
en los puntos de control de las subcuencas y el método de Muskingum para estimar los hidrogramas
de propagación de la crecida que llegan a Chañaral, para, finalmente, calcular la probabilidad de
que los caudales de los hidrogramas superen los diferentes caudales umbrales.
El presente estudio contribuye a apoyar la toma de decisiones para evacuar las zonas que se
pueden ver afectadas por inundaciones y, también, como base para la realización de planes de
emergencia.
During March 24 to 26, 2015, unusual oceanic and atmospheric conditions produced rains with very high return periods lasting approximately 48 hours over the Atacama Desert, in northern Chile, one of the most arid Earth, resulting in catastrophic flooding. The storm from March 24 to 26, 2015 generated a threshold flow flood of 997 m3 /s at the mouth of the Salado River, in the city of Chañaral. It was observed that this flood produced maximum water depths of more than 4.5 m, leaving a large amount of mud in buildings and streets of the city, this generated great material damage and loss of human life. During the date of occurrence of this episode, the Salado River basin did not have flow measurement stations that would allow anticipating the flow that would be generated at that time to the city of Chañaral. With current techniques, it is possible to determine with some precision the forecast volume and duration of a storm, but not its distribution over time. A tool was proposed to estimate the probability of exceeding different threshold flows, based on the volume of predicted precipitation and its duration. An ARMA model was built to generate a set of synthetic hyetographs for precipitation with return periods between 50 and 10,000 years, with random durations of uniform distribution between 12 and 72 hours. A semi-distributed model of the basin contributing to Chañaral was built, the curve number method was used to estimate the effective precipitation, the synthetic unit hydrograph method was used to estimate the flow at the control points of the subbasins and the Muskingum to estimate the flood propagation hydrographs that reach Chañaral, to, finally, calculate the probability that the hydrograph flows exceed the different threshold flows. This study contributes to supporting decision-making to evacuate areas that may be affected by floods and also as a basis for carrying out emergency plans.
During March 24 to 26, 2015, unusual oceanic and atmospheric conditions produced rains with very high return periods lasting approximately 48 hours over the Atacama Desert, in northern Chile, one of the most arid Earth, resulting in catastrophic flooding. The storm from March 24 to 26, 2015 generated a threshold flow flood of 997 m3 /s at the mouth of the Salado River, in the city of Chañaral. It was observed that this flood produced maximum water depths of more than 4.5 m, leaving a large amount of mud in buildings and streets of the city, this generated great material damage and loss of human life. During the date of occurrence of this episode, the Salado River basin did not have flow measurement stations that would allow anticipating the flow that would be generated at that time to the city of Chañaral. With current techniques, it is possible to determine with some precision the forecast volume and duration of a storm, but not its distribution over time. A tool was proposed to estimate the probability of exceeding different threshold flows, based on the volume of predicted precipitation and its duration. An ARMA model was built to generate a set of synthetic hyetographs for precipitation with return periods between 50 and 10,000 years, with random durations of uniform distribution between 12 and 72 hours. A semi-distributed model of the basin contributing to Chañaral was built, the curve number method was used to estimate the effective precipitation, the synthetic unit hydrograph method was used to estimate the flow at the control points of the subbasins and the Muskingum to estimate the flood propagation hydrographs that reach Chañaral, to, finally, calculate the probability that the hydrograph flows exceed the different threshold flows. This study contributes to supporting decision-making to evacuate areas that may be affected by floods and also as a basis for carrying out emergency plans.
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Proyecto de título (Ingeniera Civil)
Keywords
Caudales, Mediciones, Escorrentía, Chile, Río Salado