Homework and design project work must be organized and

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Unformatted text preview: n reserve in the Merrill Library Lecture notes by Merkley and Allen are required We will also use other reference materials during the semester III. Homework and Design Project • • • • • Work must be organized and neat Working in groups is all right, but turn in your own work Computer programming and spreadsheet exercises Submitting work late (10% per day, starting after class) Sprinkle or trickle system design project IV. Tests, Quizzes, and Grading Policy • • • Maybe some quizzes (these will not be announced) Two mid-term exams Final exam is comprehensive V. Units • • It is often necessary to convert units in design calculations Make it a habit to perform dimensional analysis when using equations; only in some of the empirical equations will the units not work out correctly VI. Irrigation Systems • • On-farm level (field) Project level (storage, conveyance, tertiary) Sprinkle & Trickle Irrigation Lectures Page 9 Merkley & Allen VII. General Types of On-Farm Irrigation Systems Type Surface Sprinkler Micro Irrigation Sub-Irrigation U.S. Area World Area 65% 95% 30% 3% 3% 1% 2% 1% These are approximate percent areas VIII. Sprinkler Systems Important Advantages 1. effective use of small continuous streams of water 2. greater application uniformity on non-homogeneous soils (provided there is no appreciable surface runoff) 3. ability to adequately irrigate steep or undulating topographies w/o erosion 4. good for light and frequent irrigation where surface irrigation may be used later in the growing season 5. labor is only needed for a short time each day (unless there are many fields) 6. labor can be relatively unskilled (pipe moving) 7. automation is readily available for many sprinkler systems 8. can be effective for weather (micro-climate) modification Important Disadvantages 1. initial cost can be high (compared to surface irrigation systems) at $500 to $3500 per ha 2. operating cost (energy) can be high compared to non-pressurized systems, unless sufficient head is available from a gravity-fed supply 3. water quality can be a problem with overhead sprinklers if water is saline, and in terms of clogging and nozzle wear. Also, some types of water are corrosive to sprinkler pipes and other hardware 4. some fruit crops cannot tolerate wet conditions during maturation (unless fungicides, etc., are used) 5. fluctuating flow rates at the water source can be very problematic 6. irregular field shapes can be difficult to accommodate 7. very windy and very dry conditions can cause high losses 8. low intake rate soils (< 3 mm/hr) cannot be irrigated by sprinkler w/o runoff IX. Slides of Sprinkler Systems [these will be shown in class] Merkley & Allen Page 10 Sprinkle & Trickle Irrigation Lectures...
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