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- Title
Increased Nonstationarity of Stormflow Threshold Behaviors in a Forested Watershed Due to Abrupt Earthquake Disturbance.
- Authors
Guotao Zhang; Peng Cui; Gualtieri, Carlo; Bazai, Nazir Ahmed; Xueqin Zhang; Zhengtao Zhang
- Abstract
Extreme earthquake disturbances to local and regional landscape vegetation could rapidly impair original hydrologic functioning, significantly increasing the hydrologic nonstationarity and complexity in threshold behaviors of rainfall-runoff processes. It is unclear how alternating catchment behaviors under an ongoing large earthquake disruption are mediated by long-term interactions of landslides and vegetation evolutions. In a famous Wenchuan earthquake-affected watershed, China, the presence and form of three-linear stormflow threshold behaviors are examined, and both thresholds are identified as a diagnostic tool to characterize variations in hydrologic emergent patterns pre- and post-earthquake. It was revealed that lower rising threshold (Tr) value (210.48) in post-earthquake landslide regions exhibited faster stormflow responses, possibly triggering huge flood disasters. An integrated watershed average (IWA) index for both thresholds (generation threshold Tg-IWA and Tr-IWA) at the watershed scale was proposed based on long-term vegetation dynamics and threshold-based hydrological theory. The interannual variations of both hydrologic thresholds were assessed to detect the nonstationarity in hydrologic extremes and nonlinear runoff response pre- and post-earthquake. 2011 was a tipping point of the unsteady recovery process, as post-earthquake landslides evolutions reached a state of extreme heterogeneity in space. At that moment, the Tr-IWA value at the watershed scale decreased by ~ 9 mm compared to the pre-earthquake level, and the fast expansion of landslides generally led to a larger extension of variable source area from channel to neighboring hillslopes and faster subsurface stormflow contributing to flash floods. Additionally, we present a conceptual model interpreting how the short- and long-term interactions of earthquake-induced landslides and vegetation affect flood hydrographs at event timescale that generated an increased nonstationary hydrologic behavior. This study expands our knowledge about the threshold-based hydrological behavior and the nonstationary stormflow threshold behaviors in response to abrupt earthquake disturbance for the prediction of future flood regimes.
- Subjects
CHINA; LANDSLIDES; EARTHQUAKES; WATERSHEDS; EARTHQUAKE prediction; VEGETATION dynamics; CONCEPTUAL models
- Publication
Hydrology & Earth System Sciences Discussions, 2022, p1
- ISSN
1812-2108
- Publication type
Article
- DOI
10.5194/hess-2022-315