There is a fundamental difference between the hydrologic response function and the transit time distribution – the former is a function of the catchment and reports how fast and how strongly the catchment responds to precipitation inputs while the latter describes individual precipitation events and characterizes the transport and storage of water particles throughout a catchment assigning a water age to each particle. Plotting both the hydrologic response function and the transit time distribution on one graph reveals the varying fractions of preevent water and allows for a qualitative assessment of dominant flow paths for individual precipitation events. Additionally, time series of varying hydrologic response functions and transit time distributions can be used to investigate the main controls of catchment response and transit times by relating them to topographical, soil and event parameters. Finally, it is also possible to integrate the changing hydrologic response functions and transit time distributions over time to construct master distributions. These are expressions of the catchment’s general response and storage behavior and can thus be utilized to compare and hydrologically classify different catchments. Data from various catchments is used to illustrate these points.
Heidbuechel I., Troch P.A. (2013): Using Hydrologic Response Functions and Transit Time Distributions to Investigate Dynamic Catchment Behavior (Invited). Abstract H44B-02 presented at 2013 Fall Meeting, AGU, San Francisco, CA, 9-13 Dec..
This Paper/Book acknowledges NSF CZO grant support.