Preprints
https://doi.org/10.5194/hess-2021-264
https://doi.org/10.5194/hess-2021-264

  25 May 2021

25 May 2021

Review status: this preprint is currently under review for the journal HESS.

Diagnosing the impacts of permafrost on catchment hydrology: field measurements and model experiments in a mountainous catchment in western China

Hongkai Gao1,2, Chuntan Han3, Rensheng Chen3, Zijing Feng2, Kang Wang1,2, Fabrizio Fenicia4, and Hubert Savenije5 Hongkai Gao et al.
  • 1Key Laboratory of Geographic Information Science (Ministry of Education of China), East China Normal University, Shanghai, China
  • 2School of Geographical Sciences, East China Normal University, Shanghai, China
  • 3Qilian Alpine Ecology and Hydrology Research Station, Key Lab. of Ecohydrology of Inland River Basin, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 4Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dubendorf, Switzerland
  • 5Delft University of Technology, Delft, the Netherlands

Abstract. Increased attention directed at permafrost hydrology has been prompted by climate change. In spite of an increasing number of field measurements and modeling studies, the impacts of permafrost on hydrological processes at the catchment scale are still unclear. Permafrost hydrology models at the catchment scale were mostly developed based on a “bottom-up” approach, hence by aggregating prior knowledge at the spot/field scales. In this study, we followed a “top-down” approach to learn from field measurement data to understand permafrost hydrology at the catchment scale. In particular, we used a stepwise model development approach to examine the impact of permafrost on streamflow response in the Hulu catchment in western China. We started from a simple lumped model (FLEX-L), and step-wisely included additional complexity by accounting for topography (i.e. FLEX-D) and landscape heterogeneity (i.e. FLEX-Topo). The final FLEX-Topo model, was then analyzed using a dynamic identifiability analysis (DYNIA) to investigate parameters’ temporal variation. By enabling temporal dynamics on several parameters, we diagnosed the physical relationships between parameter variation and permafrost impacts. We found that in the Hulu catchment: 1) the improvement associated to the model modifications suggest that topography and landscape heterogeneity are dominant controls on catchment response; 2) baseflow recession in permafrost regions is the result of a linear reservoir, and slower than non-permafrost regions; 3) parameters variation infers seasonally non-stationary precipitation-runoff relationships in permafrost catchment; 4) permafrost impacts on streamflow response mostly at the beginning of the melting season; 5) allowing the temporal variations of frozen soil related parameters, i.e. the unsaturated storage capacity and the splitter of fast and slow streamflow, improved model performance. Our findings provide new insights on the impact of permafrost on catchment hydrology in vast mountain regions of western China. More generally, they help to understand the effect of climate change on permafrost hydrology.

Hongkai Gao et al.

Status: open (until 20 Jul 2021)

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Hongkai Gao et al.

Hongkai Gao et al.

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Short summary
Permafrost hydrology is one of the 23 major unsolved problems in hydrology. In this study, we used a stepwise modeling and dynamic parameter method to examine the impact of permafrost on streamflow in the Hulu catchment in western China. We found that: topography and landscape are dominant controls on catchment response; baseflow recession is slower than other regions; precipitation-runoff relationship is non-stationary; permafrost impacts on streamflow mostly at the beginning of melting season.