Commentary: On the water footprint as an indicator of water use in food production

Flashcards about water footprint in food production, based on lecture notes.

What is the water footprint (WF)?

The volume of water used per unit food produced.

What is the green water footprint?

Water from precipitation stored in the root zone and used by plants.

What is the blue water footprint?

Water sourced from surface or groundwater that is evaporated or incorporated into a product.

What is the grey water footprint?

Fresh water required to assimilate pollutants to meet water quality standards.

When may the green footprint of a crop be less than the water consumption of native vegetation?

The baseline being the water use of the natural ecosystem.

What are some criticisms of the water footprint (WF)?

Technical difficulties in deriving robust WF indicators and the absence of local opportunity cost of water.

How does a water footprint differ from a carbon footprint?

Evaporation has only a local effect, affecting the basin where it occurs.

What is water consumption in the context of hydrology?

Evaporation losses to the atmosphere.

What does the rate of evapotranspiration (ET) depend on?

It depends on the evaporative power of the atmosphere.

In a location where the only supply of water is rainfall, how does the ET of a crop surface compare to the natural vegetation?

The ET of a crop surface would be similar to the ET of the natural vegetation.

According to the text, why is computing the water footprint of fish meaningless?

It would be meaningless because evaporation from the oceans would proceed regardless of the capture of fish.

Has agriculture increased the efficiency of primary production?

Agriculture has increased the efficiency of primary production by the management of inputs and the control of biotic factors.

Compared to natural ecosystems, what is the seasonal ET from irrigated agriculture?

The seasonal ET from irrigated agriculture exceeds that of the natural ecosystems the crop replaced.

What would be the relative contribution of irrigation to enhancing global evaporation?

It would be only about 0.4%.

What percentage of our food does irrigated agriculture produce globally?

More than 40% of our food.

What is water productivity (WP) defined as the ratio of?

Production to ET.

What is the water footprint (WF) essentially the inverse of?

The inverse of water productivity (WP).

What does the success of indicators such as the Water Footprint (WF) reflect?

Society concerns regarding the use of water in food production in general, and in irrigation, in particular.

Meaningful assessments must be based on proper accounting of the water applied (AW) and its disposition, i.e. by doing what?

Quantifying the water balance.

What kind of recommendations would invaluable knowledge, from determining the fate and disposition of applied water, provide?

Technical recommendations for improvement that would have to be integrated into the socio-economic and institutional environments.