TY - JOUR
T1 - Disentangling runoff generation mechanisms
T2 - Combining isotope tracing with integrated surface/subsurface simulation
AU - Chen, Xuegao
AU - Yu, Zhongbo
AU - Yi, Peng
AU - Aldahan, Ala
AU - Hwang, Hyoun Tae
AU - Sudicky, Edward A.
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (Grant No. 42201015, U2240217, 51979072), the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant No. 2022ZB173), National Science Funds for Creative Research Groups of China (Grant No. 51421006), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA2010010307), the Special Fund of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering of China (Grant No. 520004412, 521013122), the Natural Science Foundation of Zhejiang Province (Grant No. LZJWY22D010002). The lead author thanks Aquanty for his time spent at their Waterloo, Ontario office and the training received on the use of the HGS model. We also wish to thank Prof. Jeffrey J. McDonnell from University of Saskatchewan for improving the manuscript.
Funding Information:
This work was supported by the National Natural Science Foundation of China (Grant No. 42201015, U2240217, 51979072), the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant No. 2022ZB173), National Science Funds for Creative Research Groups of China (Grant No. 51421006), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA2010010307), the Special Fund of the State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering of China (Grant No. 520004412, 521013122), the Natural Science Foundation of Zhejiang Province (Grant No. LZJWY22D010002). The lead author thanks Aquanty for his time spent at their Waterloo, Ontario office and the training received on the use of the HGS model. We also wish to thank Prof. Jeffrey J. McDonnell from University of Saskatchewan for improving the manuscript.
Publisher Copyright:
© 2023 Elsevier B.V.
PY - 2023/2
Y1 - 2023/2
N2 - The majority of runoff studies to date have reported a similar pattern of rapid rain-to-runoff conversion via overland flow and shallow subsurface water flow, as well as the ubiquity of thresholds and hysteresis in rainfall-runoff response. But each of those approaches has limitations in terms of inference and process description. Processes of water transport and mixing and how they influence runoff generation are still not well understood or quantified. In this study, HydroGeoSphere, a fully-integrated surface/subsurface flow model, was used together with stable isotopes for disentangling runoff generation mechanisms in a headwater catchment. The study area (0.21 km2) is the first-level tributary of the Xin'an Jiang River located in a humid climate region of eastern China. Water flow simulation elucidated the spatial water transport process, and isotope tracing quantified the complex water mixing process between the shallow soil and hillslope surface. This study provides insights into the rapid transformation of rainfall infiltration and mixing in soil and exfiltration to a hillslope. Results show that the stream runoff was separated into rainfall-induced overland flow (9 %), exfiltration-induced overland flow (including the 53 % of mixed water from rainfall infiltration and 6 % of the stored soil water), and subsurface flow (32 %). Exfiltration-induced overland flow was the dominant water source in the headwater catchment during a rainfall-runoff event. The mutual influence of rainfall infiltration and soil water exfiltration caused the shallow soil to rapidly become saturated, thus forming saturation excess overland flow. The consistence of estimated soil water velocity based on the integrated isotope and numerical modeling approach, at about 0.4 m/d nearby the stream channel, improved the reliability of model visualizations. Further analysis indicates that water flow paths and velocities responding to the rainfall event were attributed to the soil moisture conditions and topography. This study demonstrates that identifying the rapid mixing processes between the rain and the soil water was crucial for understanding hillslope overland flow and runoff generation in headwater catchments.
AB - The majority of runoff studies to date have reported a similar pattern of rapid rain-to-runoff conversion via overland flow and shallow subsurface water flow, as well as the ubiquity of thresholds and hysteresis in rainfall-runoff response. But each of those approaches has limitations in terms of inference and process description. Processes of water transport and mixing and how they influence runoff generation are still not well understood or quantified. In this study, HydroGeoSphere, a fully-integrated surface/subsurface flow model, was used together with stable isotopes for disentangling runoff generation mechanisms in a headwater catchment. The study area (0.21 km2) is the first-level tributary of the Xin'an Jiang River located in a humid climate region of eastern China. Water flow simulation elucidated the spatial water transport process, and isotope tracing quantified the complex water mixing process between the shallow soil and hillslope surface. This study provides insights into the rapid transformation of rainfall infiltration and mixing in soil and exfiltration to a hillslope. Results show that the stream runoff was separated into rainfall-induced overland flow (9 %), exfiltration-induced overland flow (including the 53 % of mixed water from rainfall infiltration and 6 % of the stored soil water), and subsurface flow (32 %). Exfiltration-induced overland flow was the dominant water source in the headwater catchment during a rainfall-runoff event. The mutual influence of rainfall infiltration and soil water exfiltration caused the shallow soil to rapidly become saturated, thus forming saturation excess overland flow. The consistence of estimated soil water velocity based on the integrated isotope and numerical modeling approach, at about 0.4 m/d nearby the stream channel, improved the reliability of model visualizations. Further analysis indicates that water flow paths and velocities responding to the rainfall event were attributed to the soil moisture conditions and topography. This study demonstrates that identifying the rapid mixing processes between the rain and the soil water was crucial for understanding hillslope overland flow and runoff generation in headwater catchments.
KW - Headwater catchment
KW - HydroGeoSphere
KW - Integrated analysis
KW - Runoff generation
KW - Stable isotope
KW - Water mixing process
UR - http://www.scopus.com/inward/record.url?scp=85146734869&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85146734869&partnerID=8YFLogxK
U2 - 10.1016/j.jhydrol.2023.129149
DO - 10.1016/j.jhydrol.2023.129149
M3 - Article
AN - SCOPUS:85146734869
SN - 0022-1694
VL - 617
JO - Journal of Hydrology
JF - Journal of Hydrology
M1 - 129149
ER -