Rainfall temporal patterns

(a) ARR 1987 patterns

Australian Rainfall and Runoff (1987) offered sets of rainfall patterns or design storms for various parts of Australia for average recurrence intervals from 1 to 100 years and durations from 5 minutes to 72 hours. These design storms can be used in calculations for design or analysis of some hydrological system, with one storm being run at a time, and the worst-case results being presented.

Storms are entered into the DRAINS rainfall data base through the a Rainfall data property sheet, and are selected for runs as major and minor storms in the Select Storms property sheet. Storms from Australian Rainfall and Runoff can be entered singly, or by a multiple-storm procedure.

In Design runs in DRAINS, calculations proceed through a set of storms, defining the worst case result. In Analysis runs the program goes through each pattern separately. In both cases the resulting hydrographs can be displayed and compared.

(b) ARR 2019 patterns

Suitable temporal (time-varying) rainfall patterns is discussed in Section 5.5 of Book 5 of Chapter 2 of ARR 2019. Sets or ensembles of 10 equally-likely storms are recommended for use in hydrological analysis and design, including urban stormwater drainage applications. These are drawn from real rainfall records.

Ensembles for durations from 10 minutes to 7 days can be downloaded from the ARR Data Hub, at data.arr-software.org/. These replace the single storm patterns from Australian Rainfall and Runoff, 1987, and increase the numbers of storms to be analysed tenfold.