Agriculture Reference
In-Depth Information
4.2.6.3 Basin Irrigation Evaluation
Basins have no global slope, but the undulations of the soil surface can have an
important effect on the advance and recession process of an irrigation event.
For evaluation of basin irrigation, measurements should be made during repre-
sentative irrigation events. The required measurements are as follows:
•
advance, water depths at selected locations
•
surface drainage or recession
Commonly measured performance indices for basin irrigation are as follows:
•
application efficiency
•
distribution uniformity
•
deep percolation ratios
•
requirement efficiency or storage efficiency
For basin irrigation, tailwater ratio is zero
irrigation as
=
DU
(minimum depth infiltrated)/ (average depth infiltrated)
(4.30)
4.2.6.4 Furrow Irrigation Evaluation
Generally, the evaluation of furrow irrigation system is restricted to a single or small
number of adjacent furrows due to intensive measurement process. Complete inflow,
advance, and runoff measurements are used to accurately determine soil infiltration
rate for a small number of furrows.
The working steps and procedures for the evaluation of furrow irrigation system
are as follows:
•
Measure the length and spacing of furrow
•
Measure the soil moisture (before irrigation)
•
Install the equipments (e.g., flume, scale, moisture measuring equipment)
•
Start irrigation
•
Record the flow rate (at 5-10 min intervals, until the constant flow rate is
achieved)
•
Record the advance data after 6, 12, and 24 h from the starting of irrigation
•
Record the water depth at different points (10, 20, 50 m) at several time intervals
•
Record the cutoff time
•
Record the recession data (water depth) at several distances (10, 20, 50 m) from
the starting point at several time intervals (1/2, 1, 2, 5 h)
•
Record the depth of ponding at lower 1/4th part of furrow
•
Record the runoff volume (if the process permits)
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