Project Background

Surface Water Hydrology
Project Report
Catchment B
Group Members:
Charlie Tek – 19754358
Subash Kannabiran – 19889854
Ayush Patel – 19955663
George Koro – 19730745
Project Background
This project has been created to allow us to further our understanding and
determination of differences between catchment responses before and after it has
been developed. Currently, the catchment is undeveloped and contains three sub
catchments whereby we must choose which one we want developed.
The project requires the collaboration of four group members to complete a total of 8
tasks based on three different catchments whereby the average of the last digit of
our student ID would determine our catchment for the entirety of the project.
Task 1: Estimation of physical parameters
As soon as we had established the core members for the project, we had calculated
the average of the last digits of our team members’ student IDs and came to the
result of 5. This result lies between 3 and 6 therefore meaning that we would be
discussing catchment B. The first task asks us to estimate the area of each of the
given sub catchments that can be seen within catchment B. To do this step, we had
to locate the location of the catchment on google maps by entering the coordinates
that were provided in the project brief. Once the location was established, a
screenshot was taken and the catchment was traced out according to the project
brief for easier future reference such as outlining the catchments. We then utilised a
‘measure’ feature which allowed us to trace out an area on the map and it would
provide us with the necessary information such as the total distance around the
entire sub catchment and its total area. This process would be repeated for the three
sub catchments carefully as to ensure that the outline matches what was shown
within the project brief. Once we have all the estimated areas of the three sub
catchments, we are tasked with computing the total area of catchment B. In order to
achieve this, we simply add the three results we got from estimating the areas of
each sub catchment together. The last requirement for this task is to estimate the
length of a channel within the sub catchment. For this step, it is recommended that
we use approximation but for this instance we will be using the same feature within
google maps which we used to achieve the areas of the sub catchments. On google
maps, we locate sub catchment two which is where the channel is situated. The
point B and the outlet are marked out and the distance is measured utilising the
‘measure’ feature on google maps. It is important to note that the path is traced as
per the project briefs outline.
Total Area of Catchment B = Sub Catchment 1 Area + Sub Catchment 2 Area +
Sub Catchment 3 Area
Total Area of Catchment B = 1.72 + 3.30 + 1.92
Total Area of Catchment B = 6.94 km²
Figure 1: Catchment B split into three sub catchments Figure 2: Sub Catchment 1 Area = 1.72 km²
Figure 3: Sub Catchment 2 Area = 3.30 km² Figure 4: Sub Catchment 3 Area = 1.92 km²
Figure 5: Channel Length = 2.34 km
Task 2: Construction of Rainfall Hyetographs
A rainfall hyetograph is a graphical interpretation of rainfall intensity and the constant
interval of time. The rainfall hyetographs are used to find the DRO (Direct runoff) i.e.
the volume of water flowing in a stream without any type of loss which can be useful
to design the water system of the undeveloped catchment. As stated by the Soil
conservation service, in the 24 – hour rainfall distributions, the rainfall intensity
increases steadily until it reaches a maximum and then gradually decreases. This
brief contains the procedure of generation of total rainfall hyetograph using 1%
Annual Exceedance Probability (AEP) of a 24 – hour storm for a given catchment
area provided by the tutor. The coordinates of centroid of the catchment are 33°20’S
Latitude and 150°30’ E Longitude.
IFD curves are the representation of the distribution of the intensity of rainfall over a
specific period of time. Using the Bureau of Meteorology web site, 2016 IFD as well
as the longitude and latitude for the assigned catchment (B). The following data was
able to be produced. The latitude and longitude for catchment B are 150°30’ E
Longitude 33°20’S Latitude. Image 1 is a representation of the digital values for
Catchment B Longitude and Latitude. Upon entering the data into the BOM website
units of mm were captured first to portray table 1 in green. This table provides the
result for total rainfall in a 24-hour period to be 232 mm. This showcases the total
rainfall depth at 232mm. Changing the unit of measurement from mm to mm/h
produced table 2 in orange. This table annotates the rainfall intensity to be at 9.67
mm/h.
To find the incremental rainfall for each hour we analyse the ARR datahub ‘rare’
temporal patterns. We analyse the temporal patterns due to the rainfall intensity and
its inconstancy hence we can depict the incremental rainfall for each hour with these
temporal patterns. Analysing the average rainfall pattern and multiplying it by the
total rainfall depth, we are able to construct the rainfall hyetographs.
The ARR data hub as follows https://data-legacy.arr-software.org/ require inputting
both longitude and latitude and once achieved pressing temporal patterns option and
downloading the folder will give the access to the incremental patterns. Opening that
in excel and locating the 1440 mins, East Coast and intermediate provides the
simulation that replicates temporal patters needed to produce the desired rainfall
hyetograph.
Table 3 is constructed with the average on incremental patterns to provide column 1
and 2, and creating a graph constructed time and the average increments provide us
temporal distribution. Rainfall is calculated from the below equations.
Using the information of the storm provided in the problem statement and the IFD
curves below; rainfall intensity was 9.67 mm/hr and the total rainfall depth was
232mm.

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