Answer Happy

c) Develop the runoff hydrograph from a 22.5 km² medium density residential area located in Johor Bahru. The hydrograph is required to design the minor storm water systems of the area. Given the time of concentration, to at the outlet is 20 minutes. The design rainfall intensity, I can be taken to be 180 mm/hr and the designed temporal distribution pattern for 20 minute rainfall is presented in Table 1. The study area is shown in Figure 1. A₁ = 2km² A₂ = 4km² A3= 8km² A4 = 7km² A5 = 1.5km² 4 min A₁ Houses 8 min Houses A₂ 1 Table 1: Design rainfall Time Public park A3 12 min 0 4 8 12 16 20 Houses Public park Shops A4 16 min. Rainfall (mm) Shops 10 18 15 12.5 4.5 As 20 min 4 minutes Isochrones Figure 1: Study area with Sub-catchment and Isochrones Outlet (10 Marks)