Flood irrigation is the oldest and still the most popular crop-irrigation technique, and it can be used for large fields or even small gardens. Flood irrigation involves simply pumping or bringing water to the fields and allowing it to flow over the ground. This type of irrigation is best used in areas where water is easily accessible and cheap, because flood irrigation tends to waste a lot of water. Surge flooding and digging ponds to capture and reuse water runoff are ways to make flood irrigation more efficient in terms of water use. With some effort and planning, flood irrigation can keep your crops well-watered and healthy.
Level your fields. To ensure complete distribution of the water, make sure your fields are level. If you have a slight mound rising in the middle of your field, the crops planted on that mound won’t receive any water.
Dig two to three ponds on the edges of your field. The ponds will receive the unabsorbed water runoff from the field, so that you can capture and reuse the water instead of wasting it.
Choose a method of getting the water from its source to the fields. You can dig a ditch or canal from the water source (lake, river, etc.) to your fields. Alternately, you can set up a water pump and a pipe to bring the water to the fields. Cut holes at evenly spaced intervals in your pipe to allow the water to flow through.
Set up gates in your ditch or canal to control the water flow. The gates should be able to shut off the water flow completely, allowing you to use a surge irrigation technique. Surge irrigation involves releasing large amounts of water at timed intervals, which allows for better water distribution and less runoff.
Place a water pump and piping from the runoff ponds directly to the fields or to your canal. This pump and piping will allow you to reuse the runoff water collected in the ponds.
Consider using furrow flooding if your fields are not level in all areas. Furrow flooding involves digging small furrows, or ditches, in between the rows of crops. The furrows direct the water from the gated canals or pipes for even distribution throughout the fields.