Baseflow simulation using SWAT model in an inland river basin in Tianshan Mountains, Northwest China

Y Luo,J Arnold,X Chen,P Allen

doi:10.5194/hess-16-1259-2012

Abstract

Abstract. Baseflow is an important component in hydrological modeling. The complex streamflow recession process complicates the baseflow simulation. In order to simulate the snow and/or glacier melt dominated streamflow receding quickly during the high-flow period but very slowly during the low-flow period in rivers in arid and cold northwest China, the current one-reservoir baseflow approach in SWAT (Soil Water Assessment Tool) model was extended by adding a slow- reacting reservoir and applying it to the Manas River basin in the Tianshan Mountains. Meanwhile, a digital filter program was employed to separate baseflow from streamflow records for comparisons. Results indicated that the two-reservoir method yielded much better results than the one-reservoir one in reproducing streamflow processes, and the low-flow estimation was improved markedly. Nash-Sutcliff efficiency values at the calibration and validation stages are 0.68 and 0.62 for the one-reservoir case, and 0.76 and 0.69 for the two-reservoir case. The filter-based method estimated the baseflow index as 0.60, while the model-based as 0.45. The filter-based baseflow responded almost immediately to surface runoff occurrence at onset of rising limb, while the model-based responded with a delay. In consideration of watershed surface storage retention and soil freezing/thawing effects on infiltration and recharge during initial snowmelt season, a delay response is considered to be more reasonable. However, a more detailed description of freezing/thawing processes should be included in soil modules so as to determine recharge to aquifer during these processes, and thus an accurate onset point of rising limb of the simulated baseflow.

Highlights

Baseflow is a streamflow component which reacts slowly to rainfall and is usually associated with water discharged from groundwater storage (Eckhardt, 2008)
Conceptual modeling of baseflow usually assumes that outflow from the aquifer is linearly proportional to its storage (Aizen et al, 2000; Fenicia et al, 2006; Eckhardt, 2008; Ferket et al, 2010), sometimes combined with analytical solutions of the simplified Boussinesq equation (Paniconi et al, 2003; Troch et al, 2004; Hilberts et al, 2004)
In this study we presented a methodology to simulate baseflow processes by adding a slow-reacting linear reservoir to the available quick-reacting reservoir of baseflow generation in the SWAT model

Summary

Introduction

Baseflow is a streamflow component which reacts slowly to rainfall and is usually associated with water discharged from groundwater storage (Eckhardt, 2008). When, where, and how much streamflow can be attributed to groundwater discharge is practically important. Conceptual modeling of baseflow usually assumes that outflow from the aquifer is linearly proportional to its storage (Aizen et al, 2000; Fenicia et al, 2006; Eckhardt, 2008; Ferket et al, 2010), sometimes combined with analytical solutions of the simplified Boussinesq equation (Paniconi et al, 2003; Troch et al, 2004; Hilberts et al, 2004). Multi-reservoir algorithms, linear, non-linear, or combined were used to generate baseflow by e.g. Multi-reservoir algorithms, linear, non-linear, or combined were used to generate baseflow by e.g. Tallaksen (1995), Ferket et al (2010), and Samuel et al (2011)

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Discussion

Conclusion