Question 2: Investigate the impact of land-use changes on design flood (Upstream development

and directly connected area development)

There has been a discussion about a developing part of the Scott Creek catchment in question 1 to

create industrial and commercial precincts. The developed area will have impervious surfaces such

as shops, office blocks, and car parks. Hence, the developed area's average runoff coefficient (C₁0)

will be around 0.8.

As a civil engineering intern, the council has asked you to estimate 1 in 100-year design flood peak

and identify the most critical development scenario where:

Scenario 1: Only sub-catchment B is developed (upstream shaded area in Figure 4)

Scenario 2: Only a directly connected portion of the catchment is developed (south-eastern

shaded area within the purple boundary in Figure 5)

Stormwater runoff generated from the developed sites will flow through underground stormwater

pipes and connect to Scott Creek at the end of the developments (at point B for scenario one and D

for scenario 2). The approximate travel time of any developed area can be around 50% of its original

travel time.

For each scenario, perform the analyses by treating

a. the total catchment as one unit and

b. developed and undeveloped portions as separate sub-catchments.

Select and recommend design flood peaks for each scenario with justifications.