Abstract:
Cajas National Park, in the western Ecuadorian Andes, has been such an important water source area for the city of Cuenca that it is managed by the utility company (ETAPA) rather than by the national park system. The 50-square-kilometer Llaviucu watershed, located between 4200 m and 3000 m elevation and almost entirely in Cajas National Park, contains about 40 glacially-formed lakes and ponds and is considered the source of at least 20% of the water used in the city of Cuenca. The grass páramo cover of much of the Llaviucu watershed has been maintained for decades to centuries by burning and grazing. With grazing now greatly reduced, the national park confronts the prospect of a transition in vegetative cover and faces important questions regarding how to best manage this landscape for recreation and water supply. Soil samples representing a range of relatively moist conditions in the Llaviucu watershed typically had gravimetric soil moisture contents of 100%–250%, with more moisture held under grass than trees. Low volumetric soil moisture contents, however, indicated that soils remained well-drained. Although grass páramo soils are frequently compared to sponges, the Llaviucu watershed exhibits a flashy hydrologic response to rainfall. Key to the interpretation of this response, in Llaviucu and in the broader region, is the spatial extent of glaciation. Soils in glaciated portions of the watershed are thin (15-20 cm), histic, poorly developed, and highly permeable.
