1909-13367 SRA referral response approved docs

CO NT E NT S

1         Introduction ............................................................................................................................ 6
2         Site Description ..................................................................................................................... 6
2.1       Location and Land Use ............................................................................................................ 6

3         Hydrology ............................................................................................................................... 7
3.1       Contributing catchment parameters ........................................................................................ 7

3.1.1     Catchment area ....................................................................................................................... 7
3.1.2     Fraction impervious ................................................................................................................. 9
3.1.3     Manning’s roughness ............................................................................................................... 9
3.1.4     Initial and continuing losses ................................................................................................... 10
3.1.5     Rainfall temporal patterns ...................................................................................................... 11
3.1.6     1D Hydraulic model layout ..................................................................................................... 11
3.1.7     Determination of critical storm duration ................................................................................. 12
3.1.8     Rational method ..................................................................................................................... 13
3.1.9     2D Modelling parameters....................................................................................................... 14
3.1.10    Developed Site Drainage ....................................................................................................... 21
4         2D Modelling Results .......................................................................................................... 23
4.1       4.1 Base Case Results .......................................................................................................... 23

4.1.1     50% Aep Existing Case Results (no blockage) ..................................................................... 23
4.1.2     20% Aep Existing Results (no blockage) ............................................................................... 24
4.1.3     10% Aep Existing Results (no blockage) ............................................................................... 24
4.1.4     5% Aep Existing Results (no blockage) ................................................................................. 24
4.1.5     2% Aep Existing Results (no blockage) ................................................................................. 24
4.1.6     1% Aep Results (no blockage) .............................................................................................. 24
4.1.7     1 in 500 Year Existing Results (no blockage) ........................................................................ 25
4.1.8     1 in 2000 Year Existing Results (no blockage) ...................................................................... 25
4.1.9     PMP Existing Results (no blockage) ..................................................................................... 25
4.2       Developed Case Results ....................................................................................................... 26

4.2.1     50% Aep Results (Developed no blockage) .......................................................................... 26
4.2.2     50% Aep Results (Developed with blockage) ....................................................................... 26
4.2.3     20% Aep Results (Developed no blockage) .......................................................................... 26
4.2.4     20% Aep Results (Developed with blockage) ....................................................................... 26
4.2.5     10% Aep Results (Developed no blockage) .......................................................................... 27
4.2.6     10% Aep Results (Developed with blockage) ....................................................................... 27
4.2.7     5% Aep Results (Developed no blockage) ............................................................................ 27
4.2.8     5% Aep Results (Developed with blockage).......................................................................... 27
4.2.9     2% Aep Results (Developed no blockage) ............................................................................ 27
4.2.10    2% Aep Results (Developed with blockage).......................................................................... 28



                                                             Flood Study                                                                           3
S19-007                                               122 & 144 Myall St, Cooroy