Download Introduction - Hydrology - Lecture Slides and more Slides Water and Wastewater Engineering in PDF only on Docsity! Hydrology Introduction 1 http://science.hq.nasa.gov/oceans/images/water_cycle.jpg Docsity.com Objectives • Class Requirements • Drainage Design Overview • Review of Significant Figures • Review of Accuracy and Precision 2 Docsity.com Watershed Data • Land Use • Soil Types • Overland flow Length • Length of Channel • Slope • Vegetative Cover • Roughness Coefficient • Existing Storage • Channel Shape • Existing Drainage Structures 5 Docsity.com Delineate Watershed • Identify points of interest – Existing/Proposed Culvert Locations – Changes in Land Use – Major Stream Branching • Define Watershed Boundary • Delineate Subcatchment Areas • Determine Drainage Areas 6 Docsity.com Watershed Demo • http://techalive.mtu.edu/meec/module01/wh atiswatershed.htm 7 Docsity.com 10 Hydrograph • Graph of time vs direct runoff at one particular location – Rising limb – Crest – Falling (Recessional) Limb Docsity.com Discharge (m/s)
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Unit Hydrograph • Hydrograph representing 1” of excess precipitation occurring uniformly over the watershed for a specified storm duration 12 Docsity.com Documenting Work • Narrative on what was done and why • Map of watershed delineations • Tables summarizing info • Nomographs/equations used • References 15 Docsity.com Significant Figures • Number of digits used to form a quantity • 132, 4.01, and 0.00425 all have 3 significant figures • 350, 2500, 92,000 all have 2 significant figures • 350., 2500., 92,000. have 3, 4, and 5 significant figures, respectively 16 Docsity.com Numbers not subject to significant digits • pi • Formulas (2*pi*r)---2 is exact 17 Docsity.com Significant Digits-Computation Rules • Addition and Subtraction – Answer should have no more digits to the rights of the decimal point than the least number of digits to the right of the decimal point in any quantity in the • Example 230.1 + 20. = 250. (3 significant figures; not 2; not 4) 20 Docsity.com Significant Digits – Computation in Series • Series – If the answer to one computation is used in another computation, then the final answer is rounded to the quantity with the lowest number of significant digits 21 Docsity.com Accuracy and Precision • Accuracy-how close a value is to the actual value • Precision-how many significant digits are displayed – Avoid displaying lots of numbers because your calculator displays lots of numbers (answer looks precise but is not necessarily accurate) 22 Docsity.com
