Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 22
Narellan Creek Catchment
Flood Study
dependent on a reliable satellite signal. This can lead to less reliable measurements in areas
of high vegetation density.
2.4
Topographic Information
2.4.1
LiDAR
A variety of Light Detection and Ranging (LiDAR) datasets were available for the Narellan
Creek catchment. This includes LiDAR from 2011, 2019 as well as a LiDAR dataset that was
captured in February 2023 specifically for the current study. Details of each LiDAR dataset
are summarised in Table 3.
Table 3
Available LiDAR Datasets
Year
Collected
Month
Collected
2011
February
2019
June
2023
February
Survey Commissioned
by:
Average Point Density
(points per square
metre)
Horizontal
Vertical
1.05
±0.8
±0.3
4.00
±0.8
±0.3
>10.00
±0.2
±0.1
Spatial Services (NSW
Government)
Spatial Services (NSW
Government)
Camden Council
Accuracy (metres)
As shown in Table 3, the 2023 LiDAR comprises the highest point density and highest
horizontal and vertical accuracies. It also provides the most contemporary description of
the topography across the catchment. Therefore, the 2023 dataset was selected to develop
a Digital Elevation Model (DEM) of the catchment, which is shown in Figure 4.
However, to validate the accuracy of the 2023 LiDAR, the elevations from the DEM shown in
Figure 4 were compared against:
132 ground survey points collected across Gundungurra Reserve
152 ground survey points collected across Narellan Vale Public School
5 ground survey points collected across Magnolia Park Drainage Basins
The average and standard deviation of the elevation differences are summarised in Table 4.
Table 4
LiDAR versus ground survey elevation differences.
LiDAR Elevation – Ground Survey Elevation
(metres)
Ground Survey Dataset
Average Difference
Standard Deviation of
Difference
Gundungurra Reserve
-0.04
0.08
Narellan Vale Public School
-0.04
0.09
Magnolia Park
-0.07
