MidtermS08 - Florida International University Department of...

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Unformatted text preview: Florida International University Department of Civil and Environmental Engineering CWR3103 – Water Resources Engineering Midterm Examination This is an open book, open notes examination. It is subject to FIU Honor Code. Please follow these general instructions: 1. Choose 3 problems to solve. Do not turn in solutions for more than 3 problems. 2. Show all work and equations used. 3. Explain clearly your calculation steps. 4. Write answers legibly. 5. Sign the pledge below. 6. Return this exam sheet with your solution to Dr. Miralles before you leave the classroom. No sheets will be accepted afterwards. I, undersigned, pledge my honor that I have neither given nor received aid on this examination. Signature:________________________________________________ Printed name:_____________________________________________ Problem 1: A proposed 20 ha development consists of 5 ha of parking lots, 10 ha of buildings and 5 ha of grass areas. The grassed areas contain soils Type A in good condition. Assume AMC II conditions and a rainfall depth of 180 mm. Compute the runoff for the proposed development under the following scenarios: a) The runoff from the parking lots, building (roofs) and grass areas are each discharged separately to the drainage system. b) The runoff for the buildings (roofs) and parking lot areas are combined before discharged to the drainage system, separately from the runoff for the grass areas, which are discharged to the drainage system. c) The runoff for the parking lots, building (roofs), and grass areas are combined and then discharged to the drainage system. Problem 2: Use the National Weather Service (Chen, 1983) method to estimate the 10‐year, 25‐year and 100‐year IDF curves for Houston, TX. Estimate the 10‐year/24‐hr and 100‐ year/72‐hr rainfall depths in Houston. Problem 3: Calculate the peak runoff rate from a 20‐acre concrete surface area at an airport if the average overland flow length is 1000 m, and the average slope of the site towards the inlet is 0.6%. The site is located in an area with an IDF curve given by i = 3.6/(td + 3.0)0.99, where i is the rainfall intensity in inch/h and td is the duration in hours. Problem 4: The average rainfall over a 120 acre watershed for a particular storm was determined as follows: Hour Hourly Rainfall (in) 1 0.2 2 0.4 3 1.5 4 1.0 5 0.5 6 0.2 7 0 The volume of runoff from this storm was determined to be 19 acre‐ft. Answer the following questions: a) What is the runoff coefficient for this watershed? b) What is the curve number (CN) for this watershed? What is the cumulative infiltration F based on this curve number? c) Using a water balance, what is the initial abstraction (Ia) in this watershed? ...
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This note was uploaded on 07/09/2011 for the course CWR 3013 taught by Professor Miralles during the Spring '09 term at FIU.

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