A dimensionless approach for the runoff peak assessment: effects of the rainfall event structure
The present paper proposes a dimensionless analytical framework to investigate the impact of the rainfall event structure on the hydrograph peak. To this end a methodology to describe the rainfall event structure is proposed based on the similarity with the depth–duration–frequency (DDF) curves....
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-02-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/22/943/2018/hess-22-943-2018.pdf |
| Summary: | The present paper proposes a dimensionless analytical
framework to investigate the impact of the rainfall event structure on the
hydrograph peak. To this end a methodology to describe the rainfall event
structure is proposed based on the similarity with the
depth–duration–frequency (DDF) curves. The rainfall input consists of a
constant hyetograph where all the possible outcomes in the sample space of
the rainfall structures can be condensed. Soil abstractions are modelled
using the Soil Conservation Service method and the instantaneous unit
hydrograph theory is undertaken to determine the dimensionless form of the
hydrograph; the two-parameter gamma distribution is selected to test the
proposed methodology. The dimensionless approach is introduced in order to
implement the analytical framework to any study case (i.e. natural
catchment) for which the model assumptions are valid (i.e. linear causative
and time-invariant system). A set of analytical expressions are derived in the case of a constant-intensity hyetograph to assess the maximum runoff peak with
respect to a given rainfall event structure irrespective of the specific
catchment (such as the return period associated with the reference rainfall
event). Looking at the results, the curve of the maximum values of the
runoff peak reveals a local minimum point corresponding to the design
hyetograph derived according to the statistical DDF curve. A specific
catchment application is discussed in order to point out the dimensionless
procedure implications and to provide some numerical examples of the
rainfall structures with respect to observed rainfall events; finally their
effects on the hydrograph peak are examined. |
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| ISSN: | 1027-5606 1607-7938 |