FCT's hydrological monitoring initiative aims to understand the hydrological response to changes in vegetative cover. Studies in other areas suggest that conversion of native land cover to agricultural use within a given catchment may reduce the land's ability to regulate water flow and may alter annual water yield, as well as increasing sediment and nutrient loads. Year-round availability of water in the Nudo del Azuay is important for the downstream production of hydroelectricity, as well as for local communities and riparian ecosystems.
Permanent gauging station
In mid-2014, Fundación Cordillera Tropical established a permanent gauging station in the upper Mazar watershed. The station continuously monitors stream stage, or flow, in 15-minute intervals. An intensive campaign, currently underway, to measure stream discharge at different flow levels, will allow scientists to estimate stream discharge across all flow levels.
The station is located in the upper Mazar watershed draining 12,100 hectares of well-conserved high montane evergreen forest, shrubby and grass páramo, and a small amount of agricultural and ranching lands.
Suspended sediment production in the headwaters of the Tropical Andes
At the permanent gaging station, FCT also measures turbidity and suspended using a turbidity meter and an automated stream sampler. The turbidity meter takes regular measurements every 15 minutes, whereas the automated sampler can take periodic water samples during and following rainfall events. This project aims to correlate turbidity with suspended sediment, thereby allowing scientists to characterize temporal changes in sediment loads in a well-conserved ecosystem.
In May 2013 and 2014, Beverley Wemple, Ph.D., of the University of Vermont, visited the Nudo del Azuay. She is a forest hydrologist whose research investigates how the management of the mountain landscape alters the processes of runoff generation and sediment production in steep, headwater catchments. She advises FCT scientists in the design, installation, and analysis of the information generated at the newly established stream gaging station.
This project represents collaboration with a local hydroelectric producer, CELEC EP – Unidad de Negocio HidroAzogues, FCT, and the University of Vermont.
Data Collection and Analysis
FCT has committed to making data from this initiative available for interested researchers. Although some data years are incomplete, we publish here all weather and rainfall data collected between 2009 and 2014. Ongoing data collection will be published annually.
Precipitation - Tamiamanga (August-December)
Rainfall and run-off in paired catchments 2009-2011
Between 2010 and 2013, FCT and scientists at the University of Cuenca initiated a hydrological monitoring study in four catchments of the Pallcayacu river, varying in size from 13 to 115 hectares. This area is located in the eastern Andean cordillera, a region that exhibits strong seasonality with pronounced wet and dry seasons. Cloud cover is common year-round, and while cloud capture and stem drip are hypothesized to influence local water production, they constitute a poorly understood component of the region's hydrological cycle. Studies in other areas have shown that denuded hillsides have inefficient cloud capture and experience greater runoff following heavy rain.
In each of the four study catchments, we installed a rain collector to measure precipitation and a weir to measure surface water discharge, as well as situating two weather stations in the region. The catchments are paired: comparing well-conserved high montane evergreen forest to degraded forest with a significant proportion of pasture.
This initiative provides short-term data about weather and rain fall conditions. Following two years of work, FCT found that the atmospheric transducers used to measure stream height, or stage, functioned unreliably and would lose their calibration after a period of 10 days. FCT hypothesizes that the low atmospheric pressure found at high elevations in the Andes may have adversely affected the equipment and its measurements.
Available reports and studies related to these projects
Buytaert, W., Celleri, R., Willems, P., De Bièvre, B., & Wyseure, G. (2006). Spatial and temporal rainfall variability in mountainous areas: A case study from the south Ecuadorian Andes. Journal of Hydrology, (329), 413-421.
Guallpa, M. & R. Célleri. (2013). Efecto de la estimación de la presión atmosférica sobre el cálculo de niveles de agua y caudales. Aqua-LAC, 5(2), 56-68.
Hampel, H., Cocha, J., & Vimos, D. (2010). Incorporation of aquatic ecology to the hydrological investigation of ecosystems in the high Andes. Grupo de Ciencias de la Tierra y del Ambiente, Universidad de Cuenca.
Hampel, H. (2011). Informe Final: Determinación de los efectos de las variables ambientales sobre las comunidades de organismos acuáticos. Cuenca, Ecuador: Grupo de Ciencias de la Tierra y del Ambiente, Universidad de Cuenca.
Hartsig, J. (2011). The Effects of Land-Use Change on the Hydrological Properties of Andisols in the Ecuadorian Páramo (Master's thesis). The University of Tennessee, Knoxville, Tennessee.
Lozano, J. (2011). Impacto del cambio de coberturas en el rendimiento hídrico y la retención & producción de sedimentos en 5 subcuencas de la cuenca baja del Río Paute: análisis de escenarios utilizando el modelo InVEST. Cali, Colombia: The Nature Conservancy.
Thompson, S. (2011). Análisis histórico de la cobertura del suelo de la subcuenca del bajo río Mazar. Cuenca, Ecuador: Fundación Cordillera Tropical.