Spatial Variations in Baseflow Generation in a Headwater Mountain Catchment: Birch Creek

English Abstract:

While there has long been recognition that runoff may only be generated at isolated locales in a given watershed, baseflow contributions have often been assumed to be more spatially uniform. This study directly addresses this assumption by evaluating spatial variations in baseflow across the Birch Creek watershed, a 3227 hectare watershed, of the Upper Esopus Creek in the Southern Catskill Mountains. Approximately 150 stream flow measurements of the dendritic system within the Birch Creek catchment were completed over the course of the 2014 growing season. These discharge measurements were taken across different seasons at 33 of the 40 tributaries of the main branch of Birch Creek. A USGS gage provides continuous discharge on the main channel. Discharge measurements were normalized by area to evaluate water contribution from tributaries relative to the main channel. Results show a variety of “gaining” and “losing” streams throughout the Birch Creek catchment. Comparing to topographic features, many of the baseflow contributions to the main channel cannot solely be explained by topographic principles alone. This suggests the flow patterns of this catchment are heavily influenced by other factors, such as geologic and hydro-morphologic features. In addition to the discharge measurements, changes in the active channel network over time were observed and recorded by GPS to further demonstrate spatial variations in flow contribution at different points throughout the catchment. This study should give new insights into landscape controls on flow generation and solute transport within mesoscale catchments.