Ase 2421: Irrigation And Drainage Question Paper
Ase 2421: Irrigation And Drainage
Course:Bachelor Of Science Horticulture
Institution: Jomo Kenyatta University Of Agriculture And Technology question papers
Exam Year:2012
JOMO KENYATTA UNIVERSITY
OF
AGRICULTURE AND TECHNOLOGY
University Examinations 2012/2013
YEAR IV SEMESTER I EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE HORTICULTURE
ASE 2421: IRRIGATON AND DRIANAGE
DATE: AUGUST 2012 ¬¬¬ TIME: 2 HOURS
INSTRUCTIONS: ANSWER ANY THREE QUESTIONS
QUESTION ONE
a. Discuss the various benefits of irrigation development in Kenya and show why it is important in the semi-arid part of a country. (8 marks)
b. Discuss the environmental effects of irrigated agriculture in a newly introduced scheme. (7 marks)
c. Explain the main factors that need to be considered when selecting an appropriate irrigation method. (10 marks)
QUESTION TWO
a. Explain the differences between crop water requirement and irrigation water requirement. (6 marks)
b. Discuss factors that affect crop evapotranspiration rate and explain how actual crop water requirement is estimated at any crop growth stage. (8 marks)
c. A maize crop is grown in an area where peak design root – zone depth is 0.8 m and peak ETc is 7mm/day. The management allowable deficit (MAD) is 60%, field capacity is 28% (wt basis), permanent wilting point is 16% (wt basis), and bulk density is 1.2 g/cc. the area is sprinkler irrigated, with system efficiency estimated at 85%. A period of two days is required for various farm operations. The water is sprinkled at an average rate of 6 mm/hr. Compute the following: Net irrigation requirement, Gross water requirement, minimum irrigation interval, design interval, and duration of water application.
(10 marks)
QUESTION THREE
a. Briefly discuss the benefits of drainage in agriculture. (8 marks)
b. Discuss the possible sources of excess water in a poorly drained field. (10 marks)
c. You are requested to carry out a soil survey for improvement of a poorly drained area. Discuss the factors that would need to be considered to achieve this task. (7 mark)
QUESTION FOUR
a. Briefly discuss the procedure involved in Hoeghoult’s solution to the steady-state drainage problem. (8 marks)
b. Discuss the main differences between steady and non-steady state drainage design criteria. (7 marks)
c. Drain pipes are to be installed in an irrigated area at a depth of 7 m in a field with hydraulic conductivity of 1.5 m/day. There is an impermeable soil layer at a depth of 3 m below the soil surface. Select a suitable drain spacing to give a minimum depth of 0.5 m to the water table for a design drainage coefficient of 10 mm/day. (10 marks)
QUESTION FIVE
a. Discuss the factors that affect runoff in a watershed. (7 marks)
b. Discuss one form of soil erosion common in an ASAL region and suggest ways of mitigating this degradation of land resource. (8 marks)
c. Discuss the various methods that can be used to conserve soil and water resources in a hilly part of a region. (10 marks)
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