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 10‐ha single‐family residential development is estimated to have a curve number of 70 and a time of concentration of 15 minutes. There are no ponds or swamps on the site, and the 10‐year IDF curve is given by i =2029/(td+ 7.24)0.73 where i is the rainfall intensity in mm/h, and td is the storm duration in minutes. Estimate the peak runoff from the site, and determine the equivalent runoff coefficient that could be used with the rational method to estimate the peak runoff. Problem 2: Use the National Weather Service (Chen, 1983) method to estimate the 10‐year, 25‐year and 100‐year IDF curves for Los Angeles, CA. Estimate the 10‐year/1‐hr, 10‐
year/24‐hr and 100‐year/1‐hr rainfall depths in Los Angeles. How do these compare with the values you read from the National Weather Service maps? Problem 3: A 0.5 ha parking lot is to be drained by a single drainage inlet. The average runoff coefficient for the site is estimated to be 0.9, Manning’s n for overland flow is 0.025, the average overland flow length is 30 m, and the average slope of the site towards the inlet is 0.5%. The site is located in an area with an IDF curve given by i = 1020/(td + 8.7)0.75 where i is the rainfall intensity in mm/h and td is the duration in minutes. What is the peak runoff rate expected at the drainage inlet? Problem 4: A frivolous client hires you as a consultant to determine whether a swimming pool in his backyard has a leak. The 30 ft long x 10 ft wide x 5 ft deep pool is filled with water to the top on Jan 1. On Jan 13, a hose flowing at a rate of 10 gpm (gallons per minute) is used to add water to the pool. The hose is turned off after 8 hours. It was a very dry season, and no rainfall fell during the month. Evaporation was estimated as 3.5 inches during that month. On Feb 1, the pool is 5 inches below the top. Does the pool have a leak ? If so, what is the volume (expressed in gallons and in ft3) leaked during the month of January ? (1 ft3 = 7.48 gal) ...
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- Spring '09
- IDF, National Weather Service