Storm Drainage Design Project Essay Example | Topics and Well Written Essays - 2000 words - 1

Storm Drainage Design Project - Essay Example ertical axis using different scales, but their horizontal coordinates are the same based on hourly readings from the midnight of October 12 to 11:00 in the evening of October 15, 1998. Rainfall data was plotted using millimetres (mm) and the given observations were used as is. On the other hand, river data, which is usually plotted as a discharge in a unit of volume against time (cubic meters per second or liters per second) is drawn as a function of the given river width (B) and the velocity (V) of flow of the river (since discharge is a product of area and water flow velocity in this case) per hour of observation. The highest point (peak) of the blue line graph is 0.658 meter-BV per hour. The scale used was 1 x 10-1 m, such that 0.658 is represented as 6.58 x 10-1 m. This should explain why the highest number in the vertical axis is 7. It may be gleaned from Figure 3 that although observations were plotted every hour, the time markers were presented every three hours due to space limitations.). However, the data were analyzed using the original values and units of the river level per hour of observation. Prior to the rainfall in 4:00 on October 13, the average reading of the river height from the start of given observations for 28 consecutive hourly readings is 0.262 mm. This will be the basis of the base flow. After seven hours of rainfall, the first peak was observed at 11:00 of October 13 with a height of 1.2 mm. This marks the initiation of the rising limb of the river flood where the height of the river also started to rise compared to base flow. The rainfall data had twin peaks, with the second peak occurring at 21:00 of October or 10 hours after the first rainfall peak was observed. At 9:00 of October 14, 12 hours after the second peak of the rainfall, the peak flow of the river was recorded at 0.658 m. The amount of time for the peak flow to return back to base flow or base flow time is 46 hours. Several factors which influence the characteristics of