Page 14 - Water Pollution Management - Management Plans - Understanding your Risk

Worked example (3 of 3)

Step 5 Select Return period

2 year duration

Medium Risk

Selected return period: 1:10 yrs

(giving a 19% probability of exceedance)

Return period multiplication factor 1.48

Step 6 Calculate Peak flow:

Catchment Area x Average unit run-off x Return period factor

5 x 3.3 x =1.48 24.4l/s

= 88m /hr
3

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