Análisis de generación de escorrentía superficial en un estero intermitente del Secano Interior.
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Date
2022
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Publisher
Universidad de Concepción.
Abstract
La agricultura depende principalmente de la disponibilidad de agua en el territorio donde se encuentra, principalmente porque condiciona la producción obtenida de los cultivos que allí se pueden desarrollar. Tal es el caso del Secano Costero e Interior de Chile Central donde la actividad silvoagropecuaria debe adaptarse al ciclo de precipitaciones, al no contar con fuentes de agua e infraestructura de riego capaz de compensar la demanda hídrica en el período estival. En este trabajo se estudió la generación de caudales a dos escalas: la cuenca del estero
San José y las cuencas de los ríos Lonquén, Cauquenes y Purapel. En el caso del estero San José (7,25 km2) se estudiaron los cambios en la generación de caudales en los últimos 19 años (2001-2020) medidos en una estación fluviométrica operada por INIA para analizar el efecto de la variabilidad climática y del cambio de uso de suelo en dichos periodos a través de análisis estadísticos de los datos, determinándose que el tipo de suelo es el principal control de la
escorrentía en dicha cuenca independiente del clima y del cambio de cobertura de suelo, pues los suelos arcillosos y expansivos predominantes en esa cuenca se sellan impidiendo la infiltración en invierno. En el caso de la cuenca del río Lonquén, pese a poseer una cuenca aportante de 1160 km2 y una precipitación anual cercana a 800 mm anuales, se seca desde fines de primavera hasta el inicio del invierno austral, transformándose en un río intermitente. Lo que llama la atención es que otros ríos ubicados al norte: Cauquenes y Purapel, que poseen
menor precipitación y suelos similares, no poseen ese comportamiento. Mediante el análisis de las curvas de duración general se pudo establecer que el río Lonquén se seca durante períodos más extensos, lo que nos llevó a analizar la geología predominante de las cuencas. Se concluye que el factor que influye en el secado del río, a escala de cuenca, es la ausencia de unidades acuíferas que aporten con caudal base a la cuenca.
It is known that agriculture mainly depends on the availability of water in the territory where it is located, because that conditions the production obtained from the crops that can be grown there. Such is the case of the Dry Coastal and Interior regions of Central Chile where the forestry and agricultural activity must adapt to the rainfall cycle, as it does not have water sources or irrigation infrastructure capable of compensating the water demand during the summer period. In this work, the generation of flows was studied at two scales: the San José creek and the Lonquén, Cauquenes and Purapel river rivers. In the case of the San José watershed (7.25 km2), the changes in the generation of flows in the last 19 years (2001-2020) were studied, measured in a fluviometric station operated by INIA to analyze the effect of climatic variability and the change in land use in said periods through statistical analysis of the data, determining that the type of soil is the main control of runoff in said basin independent of the climate and the change in soil cover, since clay-expansive soils predominant in that basin are sealed preventing infiltration in winter. In the case of the Lonquén river basin, despite having a contributing basin of 1,160 km2 and an annual rainfall close to 800 mm per year, it dries from the end of spring until the beginning of the southern winter, becoming an intermittent river. What is striking is that other rivers located to the north: Cauquenes and Purapel, which have less precipitation and similar soils, do not have this behavior. Through the analysis of the general duration curves, it was possible to establish that the Lonquén River dries up during longer periods, which led us to analyze the predominant geology of the basins. It is concluded that the factor that influences the drying of the river, at the basin scale, is the absence of aquifer units that contribute with base flow to the basin.
It is known that agriculture mainly depends on the availability of water in the territory where it is located, because that conditions the production obtained from the crops that can be grown there. Such is the case of the Dry Coastal and Interior regions of Central Chile where the forestry and agricultural activity must adapt to the rainfall cycle, as it does not have water sources or irrigation infrastructure capable of compensating the water demand during the summer period. In this work, the generation of flows was studied at two scales: the San José creek and the Lonquén, Cauquenes and Purapel river rivers. In the case of the San José watershed (7.25 km2), the changes in the generation of flows in the last 19 years (2001-2020) were studied, measured in a fluviometric station operated by INIA to analyze the effect of climatic variability and the change in land use in said periods through statistical analysis of the data, determining that the type of soil is the main control of runoff in said basin independent of the climate and the change in soil cover, since clay-expansive soils predominant in that basin are sealed preventing infiltration in winter. In the case of the Lonquén river basin, despite having a contributing basin of 1,160 km2 and an annual rainfall close to 800 mm per year, it dries from the end of spring until the beginning of the southern winter, becoming an intermittent river. What is striking is that other rivers located to the north: Cauquenes and Purapel, which have less precipitation and similar soils, do not have this behavior. Through the analysis of the general duration curves, it was possible to establish that the Lonquén River dries up during longer periods, which led us to analyze the predominant geology of the basins. It is concluded that the factor that influences the drying of the river, at the basin scale, is the absence of aquifer units that contribute with base flow to the basin.
Description
Tesis para optar al grado de Magister en Ingeniería Agrícola Mención Recursos Hídricos
Keywords
Escorrentía Chile, Secano interior, Suelos, LLuvias