Course Content
Introduction
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Definition:
Importance of Irrigation in Agriculture
Physical properties of soil in relation to irrigation.
Volume and mass relationships of soil constituents
Kinds of soil water
Soil Moisture Retention and Movement
Soil moisture
Range of available water holding capacity of soil
Movement of water within Soils
Factors affecting the infiltration
Rooting characteristics and moisture extraction pattern
Effective Root Zone
Critical stages of crops for soil moisture (Moisture sensitive period)
Crop water requirement
Terminology
Measurement of ET
Types of field water losses
Farm water requirement and determination of stream size
Duty and Delta
Relationship between delta and Duty
Measurement of irrigation water
Measurement Devices
Types of weir:
Advantages of flumes
Types of orifice
Irrigation scheduling
Indicators for planning irrigation scheduling .
Method of irrigation
Adaptability of ring method:
Adaptability of border strip method
Parameters for furrow
Adaptability of furrow irrigation
Components of drip irrigation system
Advantages of Drip method of irrigation
Types of sprinkler irrigation system
Advantages of Sprinkler system
Types of irrigation system in Nepal and their Structural components
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Summary
Types of flow of irrigation depending on the source of water
Lift irrigation system:
Water Conveyance and control
Types of Open Channel
Some common terms describing flow in open channels
Estimating velocity of flow in open channels
Darcy-Weisbach Formula
Value of ‘n’ for different types of the channel
Discharge Capacity of the Channel
Permissible slope of the Earth channels
Define hydraulically best section of a channel.
Structures to control erosion in irrigation channel
Water control and diversion structures
Channel Crossing structures
Performance of farm irrigation.
Types of efficiencies
Occurrence and utilization of ground water for irrigation.
Irrigation wells
Types of Aquifier
Types of wells
Methods of well digging
Water lifting devices
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Introduction
Displacement pump
Types of reciprocating pump
Force Required to operate reciprocating pump
Pump characteristics (Parameters)
Centrifugal Pump
Principle of operation of centrifugal pump
Priming of the pump
Single stage and Multistage pump
Performance of irrigation pumps
Specific Speed
Vertical Turbine Pump:
Propeller pump
Land Grading and field layout
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Land Grading
Field layout
Reclamation of problem soils
Reclamation procedures
Field Drainage system
Problem of poor-quality water
Water quality criteria
Learn Principles and Practices of Farm Water Management with Rahul

Estimating velocity of flow in open channels

  • The design of channels is based on the mean velocity of flow which is obtained by standard formula.
  • The formula expresses the mean velocity of flow is a function of the hydraulic roughness of the channel, the hydraulic radius and the hydraulic slope.

 

Equations

  1. Vα , where C is constant depending on size.
  2. Vα , characters of slope, depth of flow of stream.
  3. Vα , nature of surface of the channel.
  4. V = C

 

  • The Equation V = C is known as Chezy’s formula .
  • Determination of value of C in this equation is comparatively difficult.
  • So, we use Manning Formula .

 

i.e. V = (R 2/3 . S ½ )/ n

 

In which ‘n’ is the roughness coefficient of channels.

 

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