Contents preface (VII) introduction 1—37

3.10.1. Water Use Subsystems
Irrigation water can be applied to croplands using one of the following irrigation methods (1): (i) Surface irrigation which includes the following:

(a) Uncontrolled (or wild or free) flooding method, (b) Border strip method,

(c) Check method, (d) Basin method, and (e) Furrow method.
(ii) Subsurface irrigation (iii) Sprinkler irrigation (iv) Trickle irrigation

SOIL-WATER RELATIONS AND IRRIGATION METHODS

113

Each of the above methods has some advantages and disadvantages, and the choice of the method depends on the following factors (2):

(i) Size, shape, and slope of the field, (ii) Soil characteristics,

(iii) Nature and availability of the water supply subsystem, (iv) Types of crops being grown,

(v) Initial development costs and availability of funds, and (vi) Preferences and past experience of the farmer.

The design of an irrigation system for applying water to croplands is quite complex and not amenable to quantitative analysis. Principal criteria for the design of a suitable irrigation method are as follows (3):

(i) Store the required water in the root-zone of the soil, (ii) Obtain reasonably uniform application of water, (iii) Minimise soil erosion,
(iv) Minimise run-off of irrigation water from the field, (v) Provide for beneficial use of the runoff water,

(vi) Minimise labour requirement for irrigation,

(vii) Minimise land use for ditches and other controls to distribute water, (viii) Fit irrigation system to field boundaries,

(ix) Adopt the system to soil and topographic changes, and

(x) Facilitate use of machinery for land preparation, cultivating, furrowing, harvesting, and so on.