Role of rainstorm intensity underestimated by data-derived flood models: Emerging global evidence from subsurface-dominated watersheds

Intense rainstorms are a prevalent feature of current weather. Evidence is presented showing that simulation of flood hydrographs shown to be dominated by subsurface flow requires watershed model parameterisation to vary between periods of different rainstorm intensity, in addition to varying with a...

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Bibliographic Details
Published in:Environmental modelling & software : with environment data news 2017-02, Vol.88, p.1-9
Main Authors: Chappell, Nick A., Jones, Tim D., Tych, Wlodek, Krishnaswamy, Jagdish
Format: Article
Language:English
Subjects:
Climate
Computer simulation
Flood
Flood hydrographs
Floods
Hydrography
Hydrologic data
Nonlinear systems
Nonlinearity
Rainfall
Rainfall intensity
Rainstorms
Rivers
Storm hydrograph
Storm seepage
Stream discharge
Stream flow
Studies
Transfer function
Watersheds
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Summary:Intense rainstorms are a prevalent feature of current weather. Evidence is presented showing that simulation of flood hydrographs shown to be dominated by subsurface flow requires watershed model parameterisation to vary between periods of different rainstorm intensity, in addition to varying with antecedent basin storage. The data show an emerging global relation between flood response and the intensity of rainstorms. Flood responses are quantified as watershed residence times (strictly time constants of nonlinear transfer-function models) identified directly from information contained within 15-min rainfall and streamflow observations. The emerging monotonic, curvilinear relation indicates that (subsurface) watershed residence time decreases as mean intensity rises, and is seen over a wide range of synoptic conditions from temperate and tropical climates. Projected increases in rainstorm intensity would then result in a greater likelihood of river floods in subsurface-dominated watersheds than is currently simulated by systems models omitting this additional nonlinearity. •Hyetograph change gives nonlinear flood responses without overland flow activation.•New storm intensity - hydrograph relationship apparent from diverse synoptic regimes.•Implications for improved flood simulation under time-varying rainfall intensity regimes.
ISSN:1364-8152
1873-6726
DOI:10.1016/j.envsoft.2016.10.009