Maps of flood statistics for regional flood frequency analysis in New Zealand |
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| Authors: | A I McKERCHAR G P PEARSON |
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| Institution: | Hydrology Centre , DSIR Marine and Freshwater , PO Box 22-037, Christchurch , New Zealand |
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| Abstract: | Abstract The two-parameter EV1 distribution adequately describes New Zealand's flood series. Contour maps of Qbar]/A0.8 and Q100Qbar] are presented, where Qbar] is the mean annual flood, A is the basin area and Q100 is the 1% annual exceedance probability flood. The maps are based directly on measured discharge series from a large sample of river recording stations. Thus when basins are ungauged, or have just a short record, an estimate of a design flood QT with specified annual exceedance probability (1/T) can be obtained using map estimates of Qbar]/A0.8 and Q100Qbar], without having first to estimate rainfall statistics for the basin, a particularly difficult task in sparsely instrumented mountainous areas. These maps succinctly summarize a great deal of hydrological information and permit improved flood frequency estimates. |
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