GRAVITY FLOW SURFACE IRRIGATION

How It Works: Water spreads over a basin or along furrows by gravity flow. Earthen borders check the spread. There may be pumps at the tail end of the field to recycle excess water (if there is any). Typical Crops: Basin: hay, grain, pasture Furrow: cotton, tomatoes, corn, cabbage, sugar beets

Basin irrigation

When It Works Well:
Fields should be prepared so they are level or slightly and evenly sloped. A farmer can calculate the amount of water to apply (irrigation scheduling) by noting the field dimensions, crop, stage of growth, climate conditions, and soil dryness. The objective: Minimize the water lost beyond the reach of plant roots, and the excess water pumped from the tail end of sloped fields.

Costs and Benefits:
Farmers close to rivers can drain their excess tail water to the natural channel or let extra water percolate below the plant roots underground back to the river, thus helping to replenish the QUANTITY of the river's flow. However, the return water carries sediment, soil salts, chemicals, and fertilizer, all of which diminish the water QUALITY in the receiving stream. Careful water scheduling benefits the environment by reducing both diversions and runoff. Since less water is diverted, less power is required to pump water to the fields.