Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. 16-Civ-B4 Engineering Hydrology, National Exams May 2017. Three hours, CLOSED BOOK with one two-sided candidate-prepared aid sheet and an approved Casio or Sharp calculator. Seven Problems are printed; any five constitute a complete paper and only the first five answers in the work book are marked. Each Problem is worth twenty (20) marks for a total of 100, and the page-1 Marking Scheme gives the sub-part split for all seven — Problems 1 and 7 at (6)(6)(8), Problem 2 at (10)(10), Problem 3 at (7)(5)(8), Problem 4 at (8)(6)(6), and Problems 5 and 6 at (7)(7)(6). Note 1 invites the candidate to state any assumptions made where a question is open to interpretation; this sitting needs that licence twice, and both places are flagged in the callout below. All seven Problems are worked here, because this set is a study resource rather than a timed sitting. Five of the seven are pure discussion; the numerical content sits in Problem 2(ii) and Problem 7(i), with short illustrative calculations added elsewhere so that each method is shown working on real numbers.
Reference texts. V. T. Chow, D. R. Maidment and L. W. Mays, Applied Hydrology (hydrologic cycle, unit hydrograph theory, Horton infiltration, level-pool and Muskingum routing, frequency analysis); W. Viessman and G. L. Lewis, Introduction to Hydrology, 5th ed. (areal precipitation, hydrograph analysis, conceptual watershed models); P. B. Bedient, W. C. Huber and B. E. Vieux, Hydrology and Floodplain Analysis, 5th ed. (rating curves, reservoir and river routing, urban design storms); R. S. Gupta, Hydrology and Hydraulic Systems, 4th ed. (groundwater recharge and discharge, streamflow measurement); L. W. Mays, Water Resources Engineering, 3rd ed. (Rational Method, IDF design practice). For the Canadian frame: Environment and Climate Change Canada IDF curve files, the Water Survey of Canada Hydrometric Manual (mid-section gauging to ISO 748), and the Transportation Association of Canada Drainage Manual for design-storm and runoff-coefficient practice.
Check — two source-data issues and one declared convention.
(1) Problem 7(i) cannot be solved as printed. A basin of 10 000 km² draining at 2200 m³/s sheds a runoff depth of 6937.92 mm in a year, which is 115.6 times the 60 mm of rain the question supplies. The water balance then returns a large negative evapotranspiration, which is physically impossible. The runoff depth follows from the area and the discharge alone and is not open to interpretation, so the printed precipitation is the term in error. The answer boxes the runoff depth from the printed data, demonstrates that the balance cannot close, and then adopts a declared corrected precipitation under Note 1. Two admissible repairs are carried through with numbers so the assumption is auditable.
(2) Problem 2(ii) gives the IDF relation without units on the intensity. The relation i = 7.0 − 0.2t is read here in mm/h, which is the Canadian convention for IDF work; the alternative in/h reading is carried through as a one-line sensitivity, and it produces a peak flow 25.4 times larger that no 10 ha suburban storm sewer would ever be sized for.
(3) Problems 1, 3, 4, 5 and 6 are discussion questions with no data of their own. Where a numerical illustration makes the method concrete, the input values are the solver's own representative figures and are labelled as such. Every number in those illustrations, and every number taken from the real source data.
