1 Vietnam National University, University of Science;

*Corresponding author:; Tel.: +84–869110757


Baseflow separation is essential for effective water management, drought assessment, and groundwater resources protection. Despite its importance, baseflow observations are often limited to small-scale studies. To address this limitation, researchers have developed various baseflow separation methods. This paper reviews and analyzes existing studies which have developed or used the baseflow separation methods. A total of 43 studies are described, with a detailed review of 26 of them, focused on baseflow separation methods. Even if existing methods have already focused on baseflow separation, however, various methods produce divergent outcomes, primarily due to the inherent challenges in directly observing the flow process associated with each technique. A minority of methods are anchored in physical science, particularly noticeable during waning streamflow periods. Notably, certain methods dynamically adjust baseflow estimates in response to precipitation intensity, an approach that, while intuitive, lacks a physical rationale and introduces subjectivity, especially when precipitation events conflate. Filter methods, despite their apparent rigor compared to graphical techniques, they suffer from a lack of physical underpinning regarding their operational frequency and orientation and are often constrained by arbitrary limits to avert baseflow estimates from surpassing total streamflow or descending into negative values. While the process-based methodology enhances accuracy by employing physical principles to gauge baseflow across both arid intervals and rainy spells, the veracity of hydrological models is intimately tied to the data’s availability and integrity. The main recommendations resulting from this review are that combining the strengths of different baseflow separation methods can lead to more robust results. For example, starting with a digital filter method for initial separation and refining it with physical-based approaches. Leveraging advancements in computational power and algorithms can help in handling complex calculations and iterative processes more efficiently, leading to more accurate baseflow estimations.


Cite this paper

Nhu, N.Y. A review on baseflow separation methodsJ. Hydro-Meteorol. 202420, 37-51.


1. Hayashi, M.; Rosenberry, D.O. Effects of ground water exchange on the hydrology and ecology of surface water. Ground Water 2002, 40(3), 309–316.

2. Eckhardt, K. How to construct recursive digital filters for baseflow separation. Hydrol. Process. 2005, 19(2), 507–515.

3. Tong, X.W.A.; Illman, Y.J.; Park, D.L.; Rudolph, S.J.; Berg. Significance of groundwater flow in hydrologic models, a model comparison study in a small watershed. Annual report submitted to the Global Water Futures Programme. 2021.

4. Brutsaert, W.; Nieber, J.L. Regionalized drought flow hydrographs from a mature glaciated plateau. Water Resour. Res. 1977, 13(3), 637–644.

5. Troch, P.A.; Berne, A.; Bogaart, P.; Harman, C.; Hilberts, A.G.J.; Lyon, S.W.; Paniconi, C.; Pauwels, V.R.N.; Rupp, D.E.; Selker, J.S.; Teuling, A.J.; Uijlenhoet, R.; Verhoest, N.E.C. The importance of hydraulic groundwater theory in catchment hydrology: The legacy of Wilfried Brutsaert and Jean-Yves Parlange. Water Resour. Res. 2013, 49(9), 5099–5116.

6. Liang, X.Y.; Zhan, H.B.; Zhang, Y.K.; Schilling, K. Base flow recession from unsaturated-saturated porous media considering lateral unsaturated discharge and aquifer compressibility. Water Resour. Res. 2017, 53, 7832–7852. 10.1002/2017WR020938.

7. Tallaksen, L.M. A review of baseflow recession analysis. J. Hydrol. 1995, 165, 349–370.

8. Hewlett, J.D.; Hibbert, A.R. Factors affecting the response of small watersheds to precipitation in humid areas. In: Sopper, W.E.; Lull, H.W. (Eds.), Int. Symp. on Forest Hydrol. Oxford. Pergamon, New York, 1967, pp. 275–290.

9. Murphy, R.; Graszkiewicz, Z.; Hill, P.; Neal, B.; Nathan, R.; Ladson, T. Australian rainfall and runoff revision project 7: Baseflow for Catchment Simulation, Stage 1 report, P7/S1/004. Engineers Australia, 2009, pp. 1–111. Available online:

10. Hall, F.R. Base flow recessions – A review. Water Resour. Res. 1968, 4(5), 973–983.

11. Chow, V.T.; Maidment, D.R.; Mays, L.W. Applied Hydrology. McGraw-Hill. 1988.

12. Nathan, R.J.; McMahon, T.A. Evaluation of automated techniques for base flow and recession analyses. Water Resour. Res. 1990, 26(7), 1465–1473.

13. Brodie, R.S.; Hostetler, S. A review of techniques for analysing baseflow from stream hydrographs. Proceedings of the NZHS-IAH-NZSSS Conference, 28 November - 2 December 2005. Auckland, New Zealand, 2005.

14. Institute of Hydrology. Low flow studies report No. 3: The estimation of low flow characteristics in rivers. Institute of Hydrology. 1980.

15. Sloto, R.A.; Crouse, M.Y. HYSEP: A computer program for streamflow hydrograph separation and analysis. US Geological Survey Water-Resources Investigations Report 96-4040. 1996.

16. Linsley, R.K.; Jr, M.A.K.; Paulhus, J.L.H. Hydrology for Engineers. McGraw-Hill, NewYork, 1982, pp. 212.

17. Available online:

18. Thakur, P.K.; Nikam, B.R.; Garg, V. et al. Hydrological parameters estimation using remote sensing and GIS for Indian region: A review. Proc. Natl. Acad. Sci., India, Sect. A Phys. Sci. 2017, 87, 641–659.

19. Birtles, A.B. Identification and separation of major baseflow components from a stream hydrograph. Water Resour Res. 1978, 14(5), 791–803.

20. Yu, X.; Schwartz, F.W. Use of environmental isotopes to estimate groundwater recharge. In Isotope Tracers in Catchment Hydrology, 1999, pp. 281–310.

21. Lyne, V.; Hollick, M. Stochastic time-variable rainfall-runoff modeling. Hydrol. Sci. Bull. 1979, 24(3), 355–372. doi:10.1080/02626667909491834.

22. Chapman, T.G.; Maxwell, A.I. A comparison of baseflow indices, which describe streamflow recession. Hydrol. Sci. J. 1996, 41(3), 399–412. doi:10.1080/02626669609491577.

23. Furey, P.R.; Gupta, H.V. A physically based filter for separating base flow from streamflow time series, Water Resour. Res. 2001, 37(11), 2709–2722.

24. Tularam, G.A.; Ilahee, M. Baseflow separation using recursive digital filters: A case study in the Upper Essequibo River Basin, Guyana. Hydrol. Processes 2008, 22(25), 4920–4930.

25. Dincer, T.; Payne, B.R.; Florkowski, T.; et al. Snowmelt runoff from measurements of tritium and oxygen 18. Water Resour. Res. 1970, 6, 110–124.

26. Wels, C.; Cornet, R.J.; LaZerte, B.D. Hydrograph separation: A comparison of geochemical and isotopic tracers. J. Hydrol. 1991, 122, 253–274.

27. Sharpe, W.E.; Kimmel, W.G.; Young, E.S.; et al. Insitu bio assays of fish mortality in two Pennsylvania Streams acidified by atmospheric deposition. Northeast. Environ. Sci. 1983, 2, 171–178.

28. Gagen, C.J.; Sharpe, W.E. Net sodium loss and mortality of three salmonid species exposed to a stream acidified by atmospheric deposition. Bull. Environ. Contam. Toxicol. 1987, 39, 7–14.

29. Bazemore, D.E.; Eshleman, K.N.; Hollenbeck, K.J. The role of soil water in stormflow generation in a forested head water catchments: Synthesis of natural tracer and hydro metric evidence. J. Hydrol. 1994, 162, 47–75.

30. Gonzales, A.L.; Nonner, J.; Heijkers, J.; Uhlenbrook, S. Comparison of different base flow separation methods in a lowland catchment. Hydrol. Earth Syst. Sci. 2009, 13, 2055–2068.

31. Eckhardt, K.A. Comparison of baseflow indices, which were calculated with seven different baseflow separation methods. J. Hydrol. 2008, 352, 168–173.

32. Duncan, H.P. Baseflow separation - A practical approach. J. Hydrol. 2019, 575, 308–313.

33. Kissel, M.; Schmalz, B. Comparison of baseflow separation methods in the German low mountain range. Water 202012, 1740.

34. Arnold, J.G.; Allen, P.M. Automated methods for estimating baseflow and groundwater recharge from streamflow records. J. Am. Water Resour. Assoc. 1999, 35(2), 411–424.

35. Mau, Y.; Winter, T.C. Comparison of base-flow estimates using graphical and digital-filter-based separation methods. Ground Water. 1997, 35(3), 453–459.

36. Xie, Y.; Zhang, Y.; Wang, D. Comparative evaluation of baseflow separation methods in the contiguous United States. J. Hydrol. 2020, 590, 125431.

37. Sun, J.; Wang, X.; Shahid, S.; et al. An optimized baseflow separation method for assessment of seasonal and spatial variability of baseflow and the driving factors. J. Geogr. Sci. 2021, 31, 1873–1894.

38. Partington, D.; Brunner, P.; Simmons, C.T.; Werner, A.D.; Therrien, R.; Maier, H.R.; Dandy, G.C. Evaluation of outputs from automated baseflow separation methods against simulated baseflow from a physically based, surface water- groundwater flow model. J. Hydrol. 2012, 458, 28–39.

39. Rutledge, A.T. Computer programs for describing the recession of ground-water discharge and for estimating mean ground-water recharge and discharge from streamflow records: Update (No. 98). US Department of the Interior, US Geological Survey. 1998.

40. Aquanty Inc. HydroGeoSphere. A three-dimensional numerical model describing fully-integrated subsurface and surface flow and solute transport. Retrieved from Waterloo, Ontario, Canada. 2018. Available online:

41. Li, L.; Maier, H.R.; Partington, D.; Lambert, M.F.; Simmons, C.T. Performance Assessment and improvement of recursive digital baseflow filters for catchments with different physical characteristics and hydrological inputs. Environ. Modell. Softw. 2014, 54, 39–52.

42. Boughton, W.C. A hydrograph-based model for estimating the water yield of ungauged catchments. In: Hydrology and Water Resources Symposium. Institution of Engineers Australia, Newcastle, NSW, 1993, pp. 317–324.

43. Su, C.H.; Peterson, T.J.; Costelloe, J.F.; Western, A.W. A synthetic study to evaluate the utility of hydrological signatures for calibrating a base flow separation filter. Water Resour. Res. 2016, 52(8), 6526–6540.