Analysis of watershed physical and hydrological effects on baseflow separation

There is a great interest in understanding groundwater-surface water interactions among hydrologists and water resources planners. One of the most challenging parts of this concept is the separation and quantification of baseflow from the streamflow hydrograph. However, in the science of hydrology, no conceptual or physical based techniques may operate effectively without considering physical and hydrological characteristics of watersheds. Hydrograph separation methods are not exceptions. Therefore, this study is widely devoted to define and test these dominant forces within a watershed and incorporate their impact on streamflow components. The study area is located in the Coastal Plain of the Southeastern United States where separately measured surface and subsurface flow data are available for a field scale watershed for nine years (1970-1978). Sensitivity analysis was conducted with respect to the impact of different watershed characteristics on streamflow components and parameters of interest were identified. Improvement in the streamflow partitioning accuracy was accomplished by incorporating the most sensitive parameters in the streamflow partitioning approach using a regression equation built based on watershed physical (e.g., land use, soils) and hydrologic characteristics (e.g. rainfall, soil moisture). Using new technique improved the streamflow partitioning method’s performance significantly. It is anticipated that these improvements will contribute to the accuracy of streamflow separation estimation for large-scale watersheds with diverse soils and cover conditions.