Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 21, 281-294, 2017
http://www.hydrol-earth-syst-sci.net/21/281/2017/
doi:10.5194/hess-21-281-2017
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
12 Jan 2017
On the non-stationarity of hydrological response in anthropogenically unaffected catchments: an Australian perspective
Hoori Ajami1,2, Ashish Sharma1, Lawrence E. Band3, Jason P. Evans4, Narendra K. Tuteja5, Gnanathikkam E. Amirthanathan6, and Mohammed A. Bari7 1School of Civil and Environmental Engineering, University of New South Wales, Sydney, Australia
2Department of Environmental Sciences, University of California Riverside, Riverside, CA, USA
3Department of Geography and Institute for the Environment, University of North Carolina, Chapel Hill, NC, USA
4Climate Change Research Centre, University of New South Wales, Sydney, Australia
5Environment and Research Division, Bureau of Meteorology, Canberra, Australian Capital Territory, Australia
6Environment and Research Division, Bureau of Meteorology, Melbourne, Victoria, Australia
7Environment and Research Division, Bureau of Meteorology, Perth, Western Australia, Australia
Abstract. Increases in greenhouse gas concentrations are expected to impact the terrestrial hydrologic cycle through changes in radiative forcings and plant physiological and structural responses. Here, we investigate the nature and frequency of non-stationary hydrological response as evidenced through water balance studies over 166 anthropogenically unaffected catchments in Australia. Non-stationarity of hydrologic response is investigated through analysis of long-term trend in annual runoff ratio (1984–2005). Results indicate that a significant trend (p < 0.01) in runoff ratio is evident in 20 catchments located in three main ecoregions of the continent. Runoff ratio decreased across the catchments with non-stationary hydrologic response with the exception of one catchment in northern Australia. Annual runoff ratio sensitivity to annual fractional vegetation cover was similar to or greater than sensitivity to annual precipitation in most of the catchments with non-stationary hydrologic response indicating vegetation impacts on streamflow. We use precipitation–productivity relationships as the first-order control for ecohydrologic catchment classification. A total of 12 out of 20 catchments present a positive precipitation–productivity relationship possibly enhanced by CO2 fertilization effect. In the remaining catchments, biogeochemical and edaphic factors may be impacting productivity. Results suggest vegetation dynamics should be considered in exploring causes of non-stationary hydrologic response.

Citation: Ajami, H., Sharma, A., Band, L. E., Evans, J. P., Tuteja, N. K., Amirthanathan, G. E., and Bari, M. A.: On the non-stationarity of hydrological response in anthropogenically unaffected catchments: an Australian perspective, Hydrol. Earth Syst. Sci., 21, 281-294, doi:10.5194/hess-21-281-2017, 2017.
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We present the first data-based framework for explaining why catchments behave in a non-stationary manner, even when they are unaffected by deforestation or urbanization. The role of vegetation dynamics in streamflow is indicated by similar or greater sensitivity of annual runoff ratio to annual fractional vegetation cover. We formulated a novel ecohydrologic catchment classification framework that incorporates the role of vegetation dynamics in catchment-scale water partitioning.
We present the first data-based framework for explaining why catchments behave in a...
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