Analysis of the Water Balance of Small Páramo Catchments in South Ecuador

Abstract

The páramo is a high altitudinal wetland ecosystem in the upper Andes of Venezuela, Colombia, Ecuador and northern Peru. It is a reliable and constant source of high quality water and as such, the major water provider for the Andean highlands and part of the coastal plains. Water is used for consumption as well as electricity production. However, scientific evidence suggests that the quality and quantity of this water source may be at risk, due to increasing human interference in the wetland ecosystem. The current study analyses the water balance of two microcatchments near Cuenca, Ecuador. One is covered by the typical natural grass vegetation, while the other catchment is heavily interfered and intensive cultivation, cattle grazing and drainage are taking place. Three rain gauges and a V-notch were installed in each catchment, and one meteorological station in a nearby location. Analysis of the precipitation data reveals that seasonal variability in the páramo is extremely low. This property is a major reason for the sustained base flow, which characterises the páramo. However, evapotranspiration, represented by the crop coefficient, is more than twice as high in the cultivated areas (0.95), compared to the natural vegetation (0.42). The increased evapotranspiration may seriously affect the water production of interfered páramo catchments. Finally, based on water balance analysis, the variation in water storage in the páramo is very low, with a yearly variation of about 25 mm. In the interfered catchment, the storage in variation is even lower, about 15 mm, suggesting a deterioration of the regulation capacity.