Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 34
Narellan Creek Catchment
Flood Study
Figure 5. The adopted impervious proportions that were applied to each land use are
summarised in Table 5.
Table 5
Adopted Impervious Percentage for Hydrologic Model
Description
Impervious Proportion
(%)
Buildings
100
Roads
100
Concrete
100
Dams/waterbodies
100
Grass/shrubs
0
Trees
0
Creek vegetation
0
A lag parameter of 1.6 was adopted for all subcatchments (the recommended lag parameter
documented in Boyd et al, 2017).
The adopted subcatchment parameters are provided in Appendix C.
Effective Impervious Area
Historically, impervious areas in hydrologic models were represented as the
