Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 55
Narellan Creek Catchment
Flood Study
Flood Study (Worley Parsons, 2015) adopted a continuing loss rate of 2.5 mm/hr in line with
ARR1987 recommendations.
For impervious areas, Section 3.5.3.1.2 of Book 5 of ARR2019 recommends a continuing loss
rate of 0 mm/hr. Therefore, the continuing loss rate of 0 mm/hr was adopted directly in the
WBNM model. The 8Narellan Creek Flood Study9 (Worley Parsons, 2015) adopted a
continuing loss rate of 1 mm/hr.
5.2.4
Temporal Patterns
ARR2019 employs 10 different temporal patterns for each AEP/storm duration to define the
time variation in rainfall during each storm. The use of a variety of different temporal
patterns is intended to reflect the natural variability of a typical rainfall event (i.e., no two
storms will be the same).
The temporal patterns for the study area were downloaded from the ARR data hub and were
used to simulate the temporal distribution of rainfall for each design storm. In accordance
with ARR2019 for catchments with an area less than 75 km2, the
