Ecological Flow to Protect Aquatic Resources on the Cebadas River, Chambo River Basin

Abstract

The assessment of ecological flow is a great challenge, which has important implications in the protection of aquatic ecosystems and socio-economic development of an area. The Tennant-Montana method provides the ability to determine ecological flows considering the relationship between aquatic habitat conditions and the average annual flow of a channel. This research presents an estimat∫e of the ecological flow at 10, 30 and 60% of the average flow and trends of the Cebadas River located in the central Andes of Ecuador through a hydrological approach during the period 1966 to 2015. The results allowed to determine an average annual flow rate of 20,768 m3/s and identify a period of avenues (May-September) and a period of dry (October-April). Long-term trend analysis using linear regression and Spearman Rho's test determined that the flow rate has remain Zvirtually unchanged for 50 years and for decade periods. The selected ecological flow was 30% of the seasonal average with values of 6.22 m3/s and 8.32 m3/s for the dry and avenue period respectively. The hydrological variability of the Cebadas River was considered because it is a restrictive factor for the development of the different aquatic species. Flow rates at 30% flow could ensure adequate development and conservation of the aquatic habitats of the Barley River while ensuring a sufficient supply of water for food security.


Keywords: Cebadas River, ecological flow, trends, tennant.


Resumen


La evaluación del caudal ecológico es un gran desafío, que tiene importantes implicaciones en la protección de ecosistemas acuáticos y desarrollo socioeconómico de una zona. El método de Tennant-Montana provee la capacidad de determinar caudales ecológicos considerando la relación entre las condiciones del hábitat acuático y el flujo anual medio de un cauce. Esta investigación presenta una estimación del caudal ecológico al 10, 30 y 60% del caudal medio y tendencias del río Cebadas ubicado en los Andes centrales del Ecuador mediante un enfoque hidrológico durante el periodo de 1966 al 2015. Los resultados permitieron determinar un caudal promedio anual de 20.768 m3/s e identificar un periodo de avenidas (mayo- septiembre) y otro de estiaje (octubre-abril). El análisis de tendencias a largo plazo mediante la regresión lineal y el test de Spearman Rho determinaron que el caudal se ha mantenido prácticamente sin cambios durante 50 años y para los períodos decadales. El caudal ecológico seleccionado fue al 30% de la media estacional con valores de 6.22 m3/s y 8.32 m3/s para el periodo de estiaje y avenida respectivamente. Se consideró la variabilidad hidrológica del río Cebadas porque constituye un factor restrictivo para el desarrollo de las diferentes especies acuáticas. Los caudales al 30% de flujo podrían asegurar un desarrollo y conservación adecuada de los hábitats acuáticos del río Cebada y al mismo tiempo garantiza un suministro suficiente de agua para la seguridad alimentaria.


Palabras claves: río Cebadas, régimen fluvial, tendencias, tennant.

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