Investigation of spatiotemporal relations between water budget components and soil water content patterns at the catchment scale
Abstract
In the framework of the TERENO project, terrestrial observatories have been implemented in order to observe hydrological phenomena at several scales, from small highly instrumented headwater catchments to mesoscale watersheds covering several 1000 sq. km (Zacharias et al., 2011). At the headwater catchment scale, field experiments are conducted in which the effects of controlled manipulation are monitored to provide empirical data describing hydrological processes and responses. The TERENO test site Wüstebach is a forested headwater catchment located in a low mountain range, Germany. With state of the art monitoring methods, the major water budget components evapotranspiration, precipitation and runoff as well as the spatial distribution of water storage have been assessed (Rosenbaum et al., 2012). This comprehensive hydrological data set offers the unique opportunity for a data-driven investigation of the spatiotemporal pattern of hydrological fluxes and states without the need to make detailed assumptions regarding the involved processes. Here, we present 3 years of measured water budget components and belowground water storage of this catchment and results of a statistical analysis using wavelet coherence transform of water budget time series and empirical orthogonal functions (EOF) of spatial soil water content pattern. The long-term water budget was closed with a residual of 3% of annual precipitation. On the daily timescale, the increasing residual of the water budget was explained to a moderate extent by soil water content (R^2 = 0.40). Wavelet coherence analysis revealed timescales of about 4 days and less, which were presumably dominated by unaccounted fast-turnover storage terms such as interception, as a major source of uncertainty. At weekly resolution, soil water storage explained more than half (R^2 = 0.62) of the water budget residual. By means of combined EOF and cluster analysis, two different spatial patterns of soil water content could be identified that switched at a mean soil water content of ~35 Vol.%. In addition, it was possible to detect non-stationary events. For instance, although a major European drought in spring 2011 had only marginal effects on the annual water budget, it was possible to detect its impact on the coherence between actual and potential evapotranspiration and on the spatial pattern of soil water content until autumn 2011. References: Rosenbaum, U., H. R. Bogena, M. Herbst, J. A. Huisman, T. J. Peterson, A. Weuthen, A. W. Western, and H. Vereecken (2012), Seasonal and event dynamics of spatial soil moisture patterns at the small catchment scale. Water Resour. Res., 48, W10544, doi: 10.1029/2011WR011518 Zacharias, S., H. Bogena, L. Samaniego and co-authors (2011), A network of terrestrial environmental observatories in Germany. Vadose Zone J., 10, 955-973, doi: 10.2136/vzj2010.0139.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.H41O..04G
- Keywords:
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- 1836 HYDROLOGY Hydrological cycles and budgets;
- 1866 HYDROLOGY Soil moisture;
- 1878 HYDROLOGY Water/energy interactions;
- 1895 HYDROLOGY Instruments and techniques: monitoring