TY - JOUR
T1 - Isotope-aided frozen soil hydrological modeling reveals freeze–thaw controls on runoff partitioning in a mountainous catchment of the upper Heihe River, China
AU - Yong, Leilei
AU - Wang, Yahui
AU - Xi, Qiaojuan
AU - Chang, Zehua
AU - Han, Chuntan
AU - Chen, Rensheng
AU - Gao, Hongkai
N1 - Publisher Copyright:
© 2026 Elsevier B.V.
PY - 2026/9
Y1 - 2026/9
N2 - The freeze-thaw processes play a critical role in regulating water partitioning in cryospheric catchments, yet their underlying mechanisms remain insufficiently quantified or poorly understood. We extended the FLEX-Topo framework to an isotope-aided version (FLEXTopo-iso) and further to a freeze-thaw-coupled cryospheric model (FLEXCryo-iso) to quantify runoff components and landscape contributions in a mountainous catchment of the upper Heihe River, China. FLEXTopo-iso shows that stable isotope constraints improve runoff component estimation, but streamflow simulation degrades without explicit frozen soil processes. FLEXCryo-iso successfully reproduces the temporal dynamics of streamflow, δ 18O, and soil freeze–thaw depth, showing markedly improved performance compared to the FLEXTopo-iso model. Source apportionment for 2013–2016 indicates groundwater dominance (69.74% ± 2.19%), followed by snow and glacier melt (17.12% ± 0.97%) and rainfall (13.14% ± 1.90%), consistent with isotope end-member validation. Spatially, runoff is mainly generated from alpine desert (58.88% ± 2.78%), supplemented by hillslope vegetation, glacier, and riparian area. During the frozen period, hydrological connectivity is minimal, and streamflow is dominated by groundwater, with hillslope vegetation in seasonally frozen soils contributing more to runoff than permafrost-limited alpine desert. During thawing, surface and subsurface flows progressively reconnect, and meltwater and rainfall begin to contribute to streamflow. During the thawed period, hydrological connectivity peaks, with groundwater remaining dominant while meltwater and rainfall jointly sustain peak flows. During refreezing, hydrological connectivity declines first at high elevations, and streamflow is sustained by delayed groundwater discharge through taliks. Runoff contributions from permafrost areas vary in parallel with seasonal changes in hydrological connectivity. By coupling isotopic constraints with explicit freeze-thaw representation, FLEXCryo-iso provides a robust framework for runoff partitioning and for understanding freeze-thaw-driven runoff and hydrological connectivity.
AB - The freeze-thaw processes play a critical role in regulating water partitioning in cryospheric catchments, yet their underlying mechanisms remain insufficiently quantified or poorly understood. We extended the FLEX-Topo framework to an isotope-aided version (FLEXTopo-iso) and further to a freeze-thaw-coupled cryospheric model (FLEXCryo-iso) to quantify runoff components and landscape contributions in a mountainous catchment of the upper Heihe River, China. FLEXTopo-iso shows that stable isotope constraints improve runoff component estimation, but streamflow simulation degrades without explicit frozen soil processes. FLEXCryo-iso successfully reproduces the temporal dynamics of streamflow, δ 18O, and soil freeze–thaw depth, showing markedly improved performance compared to the FLEXTopo-iso model. Source apportionment for 2013–2016 indicates groundwater dominance (69.74% ± 2.19%), followed by snow and glacier melt (17.12% ± 0.97%) and rainfall (13.14% ± 1.90%), consistent with isotope end-member validation. Spatially, runoff is mainly generated from alpine desert (58.88% ± 2.78%), supplemented by hillslope vegetation, glacier, and riparian area. During the frozen period, hydrological connectivity is minimal, and streamflow is dominated by groundwater, with hillslope vegetation in seasonally frozen soils contributing more to runoff than permafrost-limited alpine desert. During thawing, surface and subsurface flows progressively reconnect, and meltwater and rainfall begin to contribute to streamflow. During the thawed period, hydrological connectivity peaks, with groundwater remaining dominant while meltwater and rainfall jointly sustain peak flows. During refreezing, hydrological connectivity declines first at high elevations, and streamflow is sustained by delayed groundwater discharge through taliks. Runoff contributions from permafrost areas vary in parallel with seasonal changes in hydrological connectivity. By coupling isotopic constraints with explicit freeze-thaw representation, FLEXCryo-iso provides a robust framework for runoff partitioning and for understanding freeze-thaw-driven runoff and hydrological connectivity.
KW - FLEX-iso model
KW - FLEX-iso model
KW - Soil freeze-thaw
KW - Stable isotopes
KW - Upper Heihe River
UR - https://www.scopus.com/pages/publications/105039679189
U2 - 10.1016/j.catena.2026.110272
DO - 10.1016/j.catena.2026.110272
M3 - 文章
AN - SCOPUS:105039679189
SN - 0341-8162
VL - 271
JO - Catena
JF - Catena
M1 - 110272
ER -