Question

sestion 6 a) Briefly summarise five examples of Sustainable Drainage Systems TEL REF TEL (10) LENTES b) The inflow hydrograph for a certain river is shown in the table below. Route this inflow through the river reach using the Muskingum method to determine outflow. The travel time of the peak (K) is 1hr, the weighting of inflow Vs outflow (X) is 0.3 and the initial outflow at the start of the inflow is 3m3/s. (10) c) Draw the hydrograph and hence determine the attenuation and translation (5) 0 1 2 3 4 5 Time period (hr) In flow (mºs) nowcem o 13 Table Question 6

Answer 1

a Five examples of suistainable Drainage system :- 1. Green roof These are Landscaped or vegetated areas on the roofs of buildings, It helps drainage Systems by off setting peak discharge from Otherwise hardscape surfaces and filtering rainwater directly as it falls. It also have advantage of reducing water energy consumption and receive direct sunlight into the roofs. 2. Detention basins Detention basins (ox retention basins) are the Storm watex detention areas meant to offset excess water that could overrun the capacity of current filtration. It reduces peaks discharge into drainage Systems by mel hods including slow down Yun off velocity. It can be wet or dry depends on

whether. Io abood woddeisn bas costo modo 3. Bios wales It is a shallow depression in a piece of land meant to gather and filtey stoom waley fun off by directing Polluted rain wadey through the venetation. Swala to whol Abuso b int bastamatupiste u permeable Pavement It provides a manner for water that falls on hardscaping to seep through to the soil below. This is used by eithex dividing traditional Pavement merterials into different sections, or using a porous Pavement material, 5. wet lands of_Sustainable Drainage In this we should construct artificial wetlands in the areas where the large volumes of Storm water surges Alte present. It is used to concentrate large volumes of runoff from

urban areas and neighbour boods. It is to remove pollutants. ballo 9911 D a o122969ob wellnde b) 2. given R= Thyla H0 ba ap on ad and inylow us outflow (X)=0.3 Dalib Initial Outflow of intlow = 3m3/s = Oo Muskingum method The routing procedure uses finite differences. suo culorum oblox malod k[x1 +61-we] of aipabenden To produce muskingum Youting earn fox 102= Col2 tc. F + C20, ③ tom trosoves harung Hoog 20 Co=K2to.st k-kato. 5t Cieku +0.5t k -Kutost Itost C2 = k-kX-0.5t cent-trost K-kutos rose Here t= At 2 | 3 u 15 ai Time period (ar) oli inflow (mols) 135 1865 18 1) Dt=1-0=1

Co= 0.5 At-ka K-kato.st So. 0-5X1-0-3x1 1- 1x0.3 +0.581 C1 = 1X0.3+0:5X1 1.0.3+0.5 [C=0.66 [co=0,1667 C₂ = 1-0.3 -0.5 1-0.3 +0.5 =o. 1667.=C2 By using can. Time (60) Inflow Co Izcil, Czoo outflow Loo 3 0.83 1.98 0.498 3.308 1.667 303 10.5u9 | 5.516 133 636 0.9198.849. 0.996 5.28 | 1.475 7.751 0.8333096 6.083. 1.29 & The horrisontal called Translation (3+2)=1 vertical - attenucrtion (10-8.00= 1.1

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