Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance

<p>Extreme earthquake disturbances to the vegetation of local and regional landscapes could swiftly impair the former hydrologic function, significantly increasing the challenge of predicting threshold behaviors of rainfall–runoff processes as well as the hydrologic system's complexity ov...

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Main Authors: G. Zhang, P. Cui, C. Gualtieri, N. A. Bazai, X. Zhang, Z. Zhang
Format: Article
Language:English
Published: Copernicus Publications 2023-08-01
Series:Hydrology and Earth System Sciences
Online Access:https://hess.copernicus.org/articles/27/3005/2023/hess-27-3005-2023.pdf
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author G. Zhang
P. Cui
P. Cui
C. Gualtieri
N. A. Bazai
X. Zhang
Z. Zhang
author_facet G. Zhang
P. Cui
P. Cui
C. Gualtieri
N. A. Bazai
X. Zhang
Z. Zhang
author_sort G. Zhang
collection DOAJ
description <p>Extreme earthquake disturbances to the vegetation of local and regional landscapes could swiftly impair the former hydrologic function, significantly increasing the challenge of predicting threshold behaviors of rainfall–runoff processes as well as the hydrologic system's complexity over time. It is still unclear how alternating catchment hydrologic behaviors under an ongoing large earthquake disruption are mediated by long-term interactions between landslides and vegetation evolution. In a well-known watershed affected by the Wenchuan earthquake, the nonlinear hydrologic behavior is examined using two thresholds with intervening linear segments. A lower rising threshold (TH<span class="inline-formula"><sub>r</sub></span>) value (210.48 mm) observed in post-earthquake local landslide regions exhibited a faster stormflow response rate than that in undisturbed forest and grassland–shrubland regions, easily triggering huge flash-flood disasters. Additionally, an integrated response metric pair (integrated watershed average generation threshold TH<span class="inline-formula"><sub>g−IWA</sub></span> and rising threshold TH<span class="inline-formula"><sub>r−IWA</sub>)</span> with areas of disparate land use, ecology, and physiography was proposed and efficiently applied to identify emergent catchment hydrologic behaviors. The interannual variation in the two integrated hydrologic thresholds before and following the earthquake was assessed to detect the temporal nonstationarity in hydrologic extremes and nonlinear runoff response. The year 2011 was an important turning point along the hydrologic disturbance–recovery timescale following the earthquake, as post-earthquake landslide evolution reached a state of extreme heterogeneity in space. At that time, the TH<span class="inline-formula"><sub>r−IWA</sub></span> value decreased by <span class="inline-formula">∼</span> 9 mm compared with the pre-earthquake level. This is closely related to the fast expansion of landslides, leading to a larger extension of variable source area from the channel to neighboring hillslopes, and faster subsurface stormflow, contributing to flash floods. Finally, we present a conceptual model interpreting how the short- and long-term interactions between earthquake-induced landslides and vegetation affect flood hydrographs at event timescale that generated an increased nonstationary hydrologic behavior. This study expands our current knowledge of threshold-based hydrologic and nonstationary stormflow behaviors in response to abrupt earthquake disturbance for the prediction of future flood regimes.</p>
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spelling doaj.art-13848675704a48a6a525f7daa91e8e502023-08-14T11:24:06ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382023-08-01273005302010.5194/hess-27-3005-2023Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbanceG. Zhang0P. Cui1P. Cui2C. Gualtieri3N. A. Bazai4X. Zhang5Z. Zhang6Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing, ChinaKey Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing, ChinaChina–Pakistan Joint Research Center on Earth Sciences, Chinese Academy of Sciences and Higher Education Commission, 45320 Islamabad, PakistanDepartment of Structures for Engineering and Architecture, University of Naples Federico II, 80125 Naples, ItalyChina–Pakistan Joint Research Center on Earth Sciences, Chinese Academy of Sciences and Higher Education Commission, 45320 Islamabad, PakistanKey Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing, ChinaThe Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, Beijing Normal University, 100875 Beijing, China<p>Extreme earthquake disturbances to the vegetation of local and regional landscapes could swiftly impair the former hydrologic function, significantly increasing the challenge of predicting threshold behaviors of rainfall–runoff processes as well as the hydrologic system's complexity over time. It is still unclear how alternating catchment hydrologic behaviors under an ongoing large earthquake disruption are mediated by long-term interactions between landslides and vegetation evolution. In a well-known watershed affected by the Wenchuan earthquake, the nonlinear hydrologic behavior is examined using two thresholds with intervening linear segments. A lower rising threshold (TH<span class="inline-formula"><sub>r</sub></span>) value (210.48 mm) observed in post-earthquake local landslide regions exhibited a faster stormflow response rate than that in undisturbed forest and grassland–shrubland regions, easily triggering huge flash-flood disasters. Additionally, an integrated response metric pair (integrated watershed average generation threshold TH<span class="inline-formula"><sub>g−IWA</sub></span> and rising threshold TH<span class="inline-formula"><sub>r−IWA</sub>)</span> with areas of disparate land use, ecology, and physiography was proposed and efficiently applied to identify emergent catchment hydrologic behaviors. The interannual variation in the two integrated hydrologic thresholds before and following the earthquake was assessed to detect the temporal nonstationarity in hydrologic extremes and nonlinear runoff response. The year 2011 was an important turning point along the hydrologic disturbance–recovery timescale following the earthquake, as post-earthquake landslide evolution reached a state of extreme heterogeneity in space. At that time, the TH<span class="inline-formula"><sub>r−IWA</sub></span> value decreased by <span class="inline-formula">∼</span> 9 mm compared with the pre-earthquake level. This is closely related to the fast expansion of landslides, leading to a larger extension of variable source area from the channel to neighboring hillslopes, and faster subsurface stormflow, contributing to flash floods. Finally, we present a conceptual model interpreting how the short- and long-term interactions between earthquake-induced landslides and vegetation affect flood hydrographs at event timescale that generated an increased nonstationary hydrologic behavior. This study expands our current knowledge of threshold-based hydrologic and nonstationary stormflow behaviors in response to abrupt earthquake disturbance for the prediction of future flood regimes.</p>https://hess.copernicus.org/articles/27/3005/2023/hess-27-3005-2023.pdf
spellingShingle G. Zhang
P. Cui
P. Cui
C. Gualtieri
N. A. Bazai
X. Zhang
Z. Zhang
Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
Hydrology and Earth System Sciences
title Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
title_full Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
title_fullStr Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
title_full_unstemmed Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
title_short Increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
title_sort increased nonstationarity of stormflow threshold behaviors in a forested watershed due to abrupt earthquake disturbance
url https://hess.copernicus.org/articles/27/3005/2023/hess-27-3005-2023.pdf
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