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CIVL 450 (1)
Final

# CIVL450-MidTerm-2011-Final.pdf

16 Pages
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School
Queen's University
Department
Civil Engineering
Course
CIVL 450
Professor
Dr.Fillion
Semester
Fall

Description
Page 1 STUDENT NUMBER:___________________________ QUEEN’S UNIVERSITY CIVL 450 - HYDRAULICS III MID-TERM EXAMINATION October 25, 2011, 12:30 – 2:30 pm, MAC001 Double-sided aid sheet and calculator permitted Q UESTION1 (25%) Use the Thornthwaite Method to estimate evapotranspiration from an agricultural area near Hastings, Ontario. The average mean monthly temperatures for the past 35 years in the Hastings area are indicated in Table 1. Hastings, Ontario is at latitude 44° N. Calculate the evapotranspiration for the growing season spanning April 1 to October 9 in Hastings, Ontario. Table 1. Average mean monthly temperature in Hastings, Ontario. Mean Monthly Temperature Month (ºC) January -9.0 February -7.3 March -1.8 April 6.1 May 13.4 June 17.8 July 18.4 August 18.2 September 13.1 October 6.3 November -1.6 December -4.3 Page 2 STUDENT NUMBER:___________________________ Page 3 STUDENT NUMBER:___________________________ Page 4 STUDENT NUMBER:___________________________ Q UESTION 2 (10%) Three rainfall gauges are located in the watershed indicated in Figure 1. A Thiessen polygon area has been drawn for each gauge. (Note: the center point is not a gauge but rather the point where all Thiessen polygons meet.) The gauge areas and rainfall intensities are reported in Table 2. Compute the area-weighted rainfall intensity with the Thiessen polygon method. Figure 1. Rainfall gauges 1-3 and corresponding Thiessen polygon areas A1-A3. Table 2: Rainfall gauge data Gauge Area Rainfall Intensity Gauge 2 (km ) (mm/h) 1 A1= 7.5 14.6 2 A2= 7.0 12.6 3 A 3 14.8 9.7 Page 5 STUDENT NUMBER:___________________________ Page 6 STUDENT NUMBER:___________________________ Q UESTION 3 TOTAL OF 25%) The 1-hr, 25 mm unit hydrograph for a 1.99 ha watershed is indicated in Table 3. (15%) a) Determine the hydrograph of direct runoff (in a table) at the outlet of the watershed for the hyetograph of rainfall excess in Table 4. What is the peak runoff rate? What is the time of rise of the direct runoff hydrograph? What is the time base of the direct runoff hydrograph? (5%) b) Is the length of rainfall excess equal to the time base of direct runoff? If so, why? If not, why not? Explain. (5%) c) What is the volume of direct runoff (in m ) produced at the outlet? Table 3. 1-hr, 25 mm unit hydrograph. Time (hr) Ordinate Runoff Rate (L/s) 0 U 0 0.0 1 U 1 7.2 2 U 2 18.5 3 U 3 33.6 4 U 4 40.1 5 U 25.2 5 6 U 6 13.7 7 U 7 0.0 Table 4. Hyetograph of rainfall excess. Time (hr) Intensity Intensity (mm/hr) 0-1 1 1.8 1-2 2 2.2 2-3 I 1.5 3 3-4 4 3.2 4-5 5 1.2 Page 7 STUDENT NUMBER:___________________________ Page 8 STUDENT NUMBER:___________________________ Q UESTION 4 TOTAL OF 15%) The hyetograph of rainfall excess for a 4-hour storm is indicated in Table 5. Use the 1 hr, 10 mm NRCS Triangular unit hydrograph to determine the direct runoff at the outlet at times t = 0, t = 1 hr, and t = 2 hr (in a table). The watershed has the following parameters: form ratio K = 0.8, watershed length = 2 km, and a time of concentration of 4 hours. Table 5. Hyetograph of rainfall excess. Intensity Time (hr) (mm/hr) 0 – 1 14.2 1 – 2 16.3 2 – 3 21.3 3 – 4 9.1 Page 9 STUDENT NUMBER:___________________________ Page 10 STUDENT NUMBER:___________________________ Q UESTION 5 (TOTAL OF 25%) The hyetograph of total rainfall in Table 6 was measured during a single storm event 2 with a network of rain gauges in a 2532 km watershed near Kingston, ON. The storm produced a direct runoff of 158,760 m at the outlet of the watershed.
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