Separation of Stormflow Hydrographs in Surface and Subsurface Flow by Perceptual Based Modelling of Channel Inflow Components

摘要

The aim of this case study was to determine the origin of stormflow runoff in a 31 ha headwater basin inWestern Germany. Therefore, the contribution of infiltration excess and saturation overland flow as well as matrix andpreferential flow has been assessed along a deeply incised channel of 300 m length. Measurable parameters and simple algorithmswere used to assess the flow rate of the different runoff components. Only the scaling parameter cf that representsconverging flow processes and controls the actual height of the saturated zone along the channel incision has beencalibrated. The results showed that during wet conditions the subsurface flow rates exceed the surface flow rates tremendously.In contrast, for the short but intense summer storm the hydrograph consists solely of surface runoff components.Obviously, the parameter cf accounts for the pre-event condition of the catchment. This leads to the conclusion, that theextension of the contributing subsurface space mainly governs stormflow processes. Further investigations shall focus onthe relationship between subsurface flow processes and the lateral and vertical extension of the saturated zone.