Linear model of storm runoff from some urban catchments in New Zealand

• Published in: Journal of hydrology (Amsterdam) Vol. 21; no. 1; pp. 13 - 33
• Main Authors: Broome, Paul, Spigel, Robert H
• Format: Journal Article
• Language: English
• Published: 01.01.1982
• Subjects: New Zealand
• ISSN: 0022-1694

Rainfall and runoff from gaged urban catchments are used to design hydrographs for ungaged New Zealand urban catchments from a given rainfall hyetograph and known catchment physiography. The linear model of a catchment, used for simplicity, is characterized by the instantaneous unit hydrograph (IUH). Harmonic analysis is used to find the IUHs for 159 rainfall-runoff events on seven New Zealand urban catchments. No single IUH is found to characterize the response of any catchment for all events. It is found that the quick-flow hydrograph may be satisfactorily generated from a known hyetograph by using an IUH with the same shape as the gamma distribution and having a peak and time to peak derived from those of the harmonic IUH. This peak-fitting gamma-IUH is described by two parameters estimated from the peak discharge and time to peak. The gamma-IUH discharge and time to peak can be regionalized by equations that include catchment physiography and rainfall. The multiple regression analyses also strongly suggest that only a single parameter, the time lag of each event, is required to find the gamma IUH for that event.