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Review of Baseflow Estimation Methods and Sensitivity Analysis to the Incorporate Parameters Application of Anzali Wetland Watershed

Kalantari, Saeed | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53602 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Ataie Ashtiani, Behzad
  7. Abstract:
  8. Quantitative estimation of baseflow is necessary for hydrological modeling of a watershed, ground-surface water interaction, water supply reliability, and vulnerability, especially during a dry period, and answering questions pertaining to the responses of human-based activities on natural ecosystems. Extensive research effort spanning more than 50 years provided collections of field, manual, and computer-based methods for baseflow separation study. In this study, a comprehensive review is carried out on the nine digital filters, six graphical methods, four tracer-mass-balance methods, fourteen recession analysis methods, and two frequency analysis methods. Sensitivity analyses of baseflow estimation to the incorporated parameter of reviewed methods are assessed using computing the sensitivity coefficient. A real-case application of nine prevailing methods are also performed on Anzali’s Wetland watershed, Iran, with an approximate area of 3610 square kilometers and by considering a long-term streamflow dataset which have been collected for 10 years and cleaned with MATLAB software in nine hydrometric stations related to the rivers ending to the wetland. Graphical methods are commonly applied to obtain the baseflow component of a flood hydrograph event with intersects of baseflow and the hydrograph's rising or falling limbs. Digital filters are automated and easy-to-use techniques, and only some of them have physical bases. Tracer-mass-balance methods have a more physical base for obtaining the contribution of groundwater to the streamflow within a catchment with a mass-balance equation. The main advantage of these methods is the accuracy of them in estimating the baseflow. Correlation between methods, mean values of baseflow and sensitivity analysis diagrams of methods are presented. The average BFI calculated by nine methods in nine stations of Anzali Wetland watershed is equal to 0.58 with a standard deviation of 0.03. Also, the average share of baseflow from the total flow discharge in this basin is equal to 55%, and the share of surface runoff is equal to 45% of the total flow. Eckhardt and Lyne and Hollick methods over-estimated the baseflow value compared to other methods therefore a calibration is suggested for these methods. Coupling Eckhardt method and Tracer-based methods can be a good approach for calibration. Integration of the results obtained from real-case study and sensitivity analyses are provided which can be used as an operational guideline to choose the appropriate methods according to the watershed and streamflow data conditions. The findings of this study can help scientists easily access or improve their functionality and evaluate the meaningfulness of the incorporated parameters concerning the baseflow estimation and hopefully solve the baseflow problem
  9. Keywords:
  10. Sensitivity Analysis ; Digital Filters ; Baseflow Separation ; Groundwater Discharge ; Tracer Based Methods ; Graphical Methods ; Surface Water and Groundwater Interaction

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