IRRIGATION

Agricultural Use of Water

Amount of Water Used

• In western US states, 70 to 95% of the fresh water supply is dedicated to irrigation

• Globally an average of 70% of our fresh water use goes to irrigate agricultural crops

• This amount is expected to rise by 14% in the next three decades

• Consumptive water use (or irrigation efficiency) ranges from 30% to 90% depending upon the irrigation technology

Sources of Water for Agriculture

Direct (incident) rainfall Groundwater

- Shallow aquifers

- Deep aquifers Surface Water

– Redirecting runoff – Stream diversions– Storage in lakes and reservoirs

Ways to Apply Irrigation Water

Flood irrigation Furrow irrigation Sprinkler irrigation Drip irrigation

Irrigation Infrastructure

Historic/Traditional - Conveyance technologies: ditches, conduits

- Gravity flow, humans & animals as a source of energy- Storage technologies: ponds, lakes- Application technologies: hand, syphon, flood

Contemporary- Conveyance technologies- Pumping technologies- Storage technologies- Application technologies

Challenges Facing Irrigated Agriculture

Water quality concerns Groundwater mining and subsidence Water rights and policy issues Cost of developing water supplies Crop types and water supply changes Competition with other types of water use Changing technologies and traditional

communities