Abstract

Hydrologic catchment response is spatially and temporally variable and therefore highly complex and difficult to predict. Factors that control hydrologic catchment response can be time-invariant, such as catchment hydraulic properties; they can also be time-variant, like precipitation event properties. In order to determine which controls dominate under different conditions and at different scales, it is necessary to apply a method that is able to track variable transit times through time and at different locations within a catchment. This is more easily done when quantitative discharge measurements are available. However, when soil water transit times are used to investigate hydrologic response on smaller scales, such quantitative discharge measurements are difficult to obtain. We developed a method that allows for the tracking of soil water transit times and we used it to compare hydrologic response of catchments and nested sub-catchments. We found that during certain time periods hydraulic and storage properties dominate hydrologic response. This is for example the case when the usually time-variant precipitation forcing approaches steady-state behavior (as it does during longer dry or wet spells). However, if precipitation forcing is variable then these time-variant controls take over and determine hydrologic response across spatial scales. These findings improve our understanding of processes that activate / deactivate predominant flowpaths and facilitate the prediction of hydrologic catchment response.

Citation

I. Heidbuechel, Troch, P.A. (2011): Determining Controls on Variable Response Times from Nested Sub-catchments. AGU Fall Meeting Presentations Abstract H43N-05..