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,
5Environment and Research Division, Bureau of Meteorology, Canberra,
Australian Capital Territory, Australia
6Environment and Research Division, Bureau of Meteorology, Melbourne,
7Environment and Research Division, Bureau of Meteorology, Perth,
Western Australia, Australia
Received: 16 Jul 2016 – Discussion started: 29 Jul 2016
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.
Revised: 14 Dec 2016 – Accepted: 16 Dec 2016 – Published: 12 Jan 2017
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.