Constraining frequency–magnitude–area relationships for rainfall and flood discharges using radar-derived precipitation estimates: example applications in the Upper and Lower Colorado River basins, USA
Flood-envelope curves (FECs) are useful for constraining the upper limit of possible flood discharges within drainage basins in a particular hydroclimatic region. Their usefulness, however, is limited by their lack of a well-defined recurrence interval. In this study we use radar-derived precipi...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://www.hydrol-earth-syst-sci.net/20/4483/2016/hess-20-4483-2016.pdf |
| Summary: | Flood-envelope curves (FECs) are useful for constraining the upper limit of
possible flood discharges within drainage basins in a particular
hydroclimatic region. Their usefulness, however, is limited by their lack of
a well-defined recurrence interval. In this study we use radar-derived
precipitation estimates to develop an alternative to the FEC method, i.e.,
the frequency–magnitude–area-curve (FMAC) method that incorporates
recurrence intervals. The FMAC method is demonstrated in two well-studied
US drainage basins, i.e., the Upper and Lower Colorado River basins (UCRB and
LCRB, respectively), using Stage III Next-Generation-Radar (NEXRAD) gridded
products and the diffusion-wave flow-routing algorithm. The FMAC method can
be applied worldwide using any radar-derived precipitation estimates. In the
FMAC method, idealized basins of similar contributing area are grouped
together for frequency–magnitude analysis of precipitation intensity. These
data are then routed through the idealized drainage basins of different
contributing areas, using contributing-area-specific estimates for channel
slope and channel width. Our results show that FMACs of precipitation
discharge are power-law functions of contributing area with an average
exponent of 0.82 ± 0.06 for recurrence intervals from 10 to 500 years.
We compare our FMACs to published FECs and find that for wet
antecedent-moisture conditions, the 500-year FMAC of flood discharge in the
UCRB is on par with the US FEC for contributing areas of ∼ 10<sup>2</sup> to
10<sup>3</sup> km<sup>2</sup>. FMACs of flood discharge for the LCRB exceed the
published FEC for the LCRB for contributing areas in the range of
∼ 10<sup>3</sup> to 10<sup>4</sup> km<sup>2</sup>. The FMAC method retains the power of
the FEC method for constraining flood hazards in basins that are ungauged or
have short flood records, yet it has the added advantage that it includes
recurrence-interval information necessary for estimating event probabilities. |
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| ISSN: | 1027-5606 1607-7938 |