Evaluación del caudal ecológico y su relación con las variaciones hidrológicas en el curso inferior del río Guayllbamba con la represa hidroeléctrica Manduriacu

Abstract

The study addresses a hydrological and hydraulic analysis of the Guayllabamba River basin up to the Manduriacu Hydroelectric Plant to determine the characteristic flow in both directions of the analysis. Based on these results, the ecological flow corresponding to the area of interest is determined, establishing the existing hydrological variations downstream of the dam. For the development of this investigative project, it is necessary to collect information on meteorological variables such as precipitation, temperature, and flow rates from daily, monthly, and annual series; as well as field data from the sections of interest such as: topography, water depth, limnimetric measurements, velocities, and water sampling. Based on these data, hydrological modeling (GR2M) and simulation in HEC-RAS provide results for basin flows. From this point, the ecological flow is defined using the methodologies of Hoppe, Tennant, 7Q10, Wet Perimeter, and the Ecuadorian method; it is considered that methodology of Hoppe equal 212.28 m³/s is the optimal result, as this value meets the requirements of the other methodologies and allows for the proper development of the aquatic ecosystem. Additionally, it is complemented by a water quality analysis in the discharge section and a hydrological balance on a multi-spatial scale with annual temporality. The study, auxiliary tools such as R-Studio scripts and geographic information system software like Q-Gis and ArcGIS are used. The dam poses an obstacle to the passage of aquatic species, and both its operation and maintenance negatively affect the surrounding areas; it manages a flow of 210 m³/s, a value that according to the hottest year since 1900, year 2015 data is only met from February to May and overall, with respect to the proposed ecological flow, there is a loss of 2.28 m³/s.