Articles | Volume 20, issue 4
Hydrol. Earth Syst. Sci., 20, 1547–1560, 2016
https://doi.org/10.5194/hess-20-1547-2016
Hydrol. Earth Syst. Sci., 20, 1547–1560, 2016
https://doi.org/10.5194/hess-20-1547-2016

Research article 22 Apr 2016

Research article | 22 Apr 2016

Assessing the impact of climate variability and human activities on streamflow variation

Jianxia Chang, Hongxue Zhang, Yimin Wang, and Yuelu Zhu Jianxia Chang et al.
  • State Key Laboratory Base of Eco-hydraulic Engineering in Arid Area, Xi'an University of Technology, Xi'an 710048, China

Abstract. Water resources in river systems have been changing under the impact of both climate variability and human activities. Assessing the respective impact on decadal streamflow variation is important for water resource management. By using an elasticity-based method and calibrated TOPMODEL and VIC hydrological models, we quantitatively isolated the relative contributions that human activities and climate variability made to decadal streamflow changes in the Jinghe basin, located in the northwest of China. This is an important watershed of the Shaanxi province that supplies drinking water for a population of over 6 million people. The results showed that the maximum value of the moisture index (E0P) was 1.91 and appeared in 1991–2000, and the decreased speed of streamflow was higher since 1990 compared with 1960–1990. The average annual streamflow from 1990 to 2010 was reduced by 26.96 % compared with the multiyear average value (from 1960 to 2010). The estimates of the impacts of climate variability and human activities on streamflow decreases from the hydrological models were similar to those from the elasticity-based method. The maximum contribution value of human activities was 99 % when averaged over the three methods, and appeared in 1981–1990 due to the effects of soil and water conservation measures and irrigation water withdrawal. Climate variability made the greatest contribution to streamflow reduction in 1991–2000, the values of which was 40.4 %. We emphasized various source of errors and uncertainties that may occur in the hydrological model (parameter and structural uncertainty) and elasticity-based method (model parameter) in climate change impact studies.

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Short summary
We quantitatively isolated the relative contributions that human activities and climate variability made to decadal streamflow changes in Jinghe basin by three methods. We concluded that the three methods were in good agreement in terms of the dominant contributor, i.e., human activities played a more important role in the streamflow decrease than climate changes. We qualitatively discussed the errors and uncertainties, and will make an attempt for further research on quantitative discussions.