Comparative analysis of baseflow characteristics of two andean catchments, Eduador

Baseflow in the Andes is commonly considered to be related with the release of water stored in páramos. Páramo is the predominant ecosystem above 3500 m a.s.l. and is characterized by a rainy and cold climate with low evapotranspiration. However, this baseflow concept is based on hydrological process studies in small Andean catchments of a few km² with a homogeneous land cover. Middle sized Andean catchments, like the sub-catchments of Tarqui and Yanuncay, Ecuador, are rarely homogeneous or uniformly covered by páramo. The objectives of this study are therefore to investigate baseflow characteristics in heterogeneous Andean catchments, and to identify relationships between baseflow processes and physical characteristics such as storage and recharge. Hereby, the contribution to baseflow of páramo and other sources such as alluvial aquifers is quantified. This study uses nonlinear recession analysis, physically based filters and digital filters for comparison of baseflow of neighbouring but distinct sub-catchments. The Yanuncay sub-catchment shows a clearly different storage capacity and recession. The storage capacity of Yanuncay is 50% higher than for Tarqui due to its higher coverage of páramo. On the other hand, considerable storage capacity has also been found in the Tarqui sub-catchment, which has a limited páramo area but a significant alluvial aquifer. It is shown that improved understanding of the specific baseflow characteristics such as storage and recharge and its relationships to the heterogeneity of the land cover in Andean catchments will lead to a better assessment of the water resources and give new insights for effective management actions.status: publishe