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- Title
Technical note: Analytical sensitivity analysis and uncertainty estimation of a two-component hydrograph separation method which uses conductivity as a tracer.
- Authors
Weifei Yang; Changlai Xiao; Xiujuan Liang
- Abstract
The conductivity two-component hydrograph separation method is cheap and easy to operate and is favored by hydrologists. This paper analyzes the sensitivity of the baseflow index (BFI, the long-term ratio of baseflow to streamflow) calculated by this method to errors or uncertainties of the two parameters (BFC, the conductivity of baseflow; ROC, the conductivity of surface runoff) and of the two variables (yk, the specific streamflow; Qck, the specific conductivity of streamflow), and then estimates the uncertainty of BFI. The analysis shows that when the time series is longer than 365 days, the random measurement errors of yk or Qck will cancel each other, and the influence on BFI can be neglected. Dimensionless sensitivity indices (the ratio of the relative error of BFI to the relative error of BFC or ROC) can well express the propagation of errors or uncertainties of BFC or ROC into BFI. Based on the sensitivity analysis, the uncertainty estimation method of BFI is derived. Representative sensitivity indices and BFI' uncertainties are yielded by application of the resulting equations to 24 watersheds in the United States. The results indicate that BFI is more sensitive to BF], and the conductivity two-component hydrograph separation method may be more suitable for the long time series in a small watershed. After considering the mutual offset of the measurement errors of conductivity and streamflow, the uncertainty of BFI is reduced by half.
- Subjects
HYDROGRAPHY; HYDROLOGISTS; STREAMFLOW; RUNOFF; TIME series analysis
- Publication
Hydrology & Earth System Sciences Discussions, 2018, p1
- ISSN
1812-2108
- Publication type
Article
- DOI
10.5194/hess-2018-492