ESS Topic 4.2 Access to freshwater

The most efficient agricultural irrigation technique in terms of using the least water is....

• spray irrigation

• flood irrigation

• furrow irrigation

• drip irrigation

Answer explanation

Drip irrigation uses the least amount of water compared to the other irrigation types as it is often burried to minimize evaporation and designed to release water at the plants roots. The other irrigation techniques are applied through the air and not plant specific spreading water often where there may not be any plants.

The correct order, from most to least, of human activities world wide that make use of fresh water is...

• agriculture, domestic and industrial

• industrial, domestic and agriculture

• agriculture, industrial and domestic

• industrial, agriculture and domestic

Answer explanation

World use of water is about 70% for agriculture, 22% for industrial and 8% for domestic

Which of the following is the least efficient use or storage of fresh water?

• Store water underground in gravel-filled reserviors

• Store water in a reservoir with a large surface area

• cover fields with plastic to reduce evaporation

• Use drip irrigation of individual plants rather than the whole field

Answer explanation

Surface reservoirs of water loose huge amounts of water to evaporation especially in arid regions.

Which of the following ground cover types permit the highest infiltration rates...

• bare ground

• old permanent pasture grazed

• old permanent pasture not grazed

• annual grains (e.g. wheat)

Answer explanation

The more time plants can develop root systems without being disturbed, the less they are exposed to factors leading to ground compaction resulting in higher the infiltration rates.

An example of physical water scarcity is....

• Industries release pollutants into water supplies that need to be cleaned before use.

• Industries release pollutants into water supplies that need to be cleaned before use.

• A ocean front city not having enough money to build a water desalinization plant.

• A community's reservoir used as its water supply is destroyed by war.

Answer explanation

Physical water scarcity is due to water being consumed faster than it can be replenished. Reduced rainfall will reduce the water supply available for use. All the other choices are examples of economic water scarcity.