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Challenges and opportunities for sustainable irrigation based on alternative water sources
Year:
2015
Source of publication :
Global Water Forum
Authors :
Assouline, Shmuel
;
.
Russo, David
;
.
Volume :
Co-Authors:

Shmuel Assouline
David Russo
Avner Silber
Prof. Dani Or

Facilitators :
From page:
0
To page:
0
(
Total pages:
1
)
Abstract:

The global human population is estimated to exceed nine billion by 2050 with associated food requirements expected to increase by more than 70 per cent. The urgent challenge of matching demand for food for a larger and more affluent population using the same land footprint will require radical changes in the way food is produced, stored, distributed, and accessed. World agriculture remains largely rainfed and, therefore, the relative contribution of the significantly more efficient irrigated agriculture will have to be more important to increase yields while using marginal water resources, like treated effluent and desalinated water.

Global estimates of potentially exploitable freshwater (FW) resources per capita and of projected global water use per capita suggest that water consumption is rapidly increasing as demonstrated by the red line in Figure 2. The estimated current level of exploitation of FW resources is approximately 15%. Figure 2 shows that higher levels of exploitation would be required in the coming decades to meet the increased per capita water use. The highest assumed exploitation level in Figure 2 (40%) represents very high anthropogenic pressure on FW resources that would be required around 2060 to ensure each person’s water use needs are met.

The need for additional water compared to current levels will be particularly critical for regions already suffering from chronic water shortage, which are expected to increase 8 fold over the same period. These trends will accentuate the competition between domestic and irrigation needs for FW resources. The mounting pressures on FW resources will, therefore, promote the use of (presently) unconventional water resources for irrigation when possible and under appropriate management practices.

The production of treated effluent (TE) rapidly increases in direct proportion to domestic FW use, especially in large urban areas. New regulations limiting the release of such effluents into waterways and into the sea in coastal regions (e.g. the Barcelona agreement), and implementation of tighter environmental regulations, favour the sustainable reuse of TE as an attractive water source for irrigated agriculture, especially in arid and semi-arid regions. The initial positive reports deemed TE a safe alternative water source for irrigation that could even present some benefits in terms of higher yields or lower fertilizer application amounts resulting from the enrichment of TE in nutrients and organic matter.

However, this seemingly simple and attractive water resource has its challenges. The negative effect of TE on soil properties and on yields was not obvious in the first few years of TE application. Evidence from research suggests that long-term use of TE (15 years) for irrigation resulted in the degradation of several physical and hydraulic properties of a clay-rich soil. The deterioration in soil properties further resulted in a significant decrease of Avocado and Citrus yields over the years (Figure 1 and Figure 3).

Some of the risks associated with TE irrigation include higher concentrations of salts (especially sodium, Na+), and of organic compounds. The combination of these ingredients increases the exchangeable sodium percentage (ESP) of irrigated soils, thereby affecting their wettability, and contributes to a deterioration of their physical and hydraulic properties. These changes affect the fluxes in the soil profile (infiltration, drainage, evaporation and gas diffusion), and consequently, the water availability for plants.

Note:
Related Files :
Freshwater resources
sustainable irrigation
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DOI :
Article number:
0
Affiliations:
Database:
Publication Type:
Conference paper
;
.
Language:
English
Editors' remarks:
ID:
56123
Last updated date:
02/03/2022 17:27
Creation date:
29/08/2021 15:59
Scientific Publication
Challenges and opportunities for sustainable irrigation based on alternative water sources

Shmuel Assouline
David Russo
Avner Silber
Prof. Dani Or

Challenges and opportunities for sustainable irrigation based on alternative water sources .

The global human population is estimated to exceed nine billion by 2050 with associated food requirements expected to increase by more than 70 per cent. The urgent challenge of matching demand for food for a larger and more affluent population using the same land footprint will require radical changes in the way food is produced, stored, distributed, and accessed. World agriculture remains largely rainfed and, therefore, the relative contribution of the significantly more efficient irrigated agriculture will have to be more important to increase yields while using marginal water resources, like treated effluent and desalinated water.

Global estimates of potentially exploitable freshwater (FW) resources per capita and of projected global water use per capita suggest that water consumption is rapidly increasing as demonstrated by the red line in Figure 2. The estimated current level of exploitation of FW resources is approximately 15%. Figure 2 shows that higher levels of exploitation would be required in the coming decades to meet the increased per capita water use. The highest assumed exploitation level in Figure 2 (40%) represents very high anthropogenic pressure on FW resources that would be required around 2060 to ensure each person’s water use needs are met.

The need for additional water compared to current levels will be particularly critical for regions already suffering from chronic water shortage, which are expected to increase 8 fold over the same period. These trends will accentuate the competition between domestic and irrigation needs for FW resources. The mounting pressures on FW resources will, therefore, promote the use of (presently) unconventional water resources for irrigation when possible and under appropriate management practices.

The production of treated effluent (TE) rapidly increases in direct proportion to domestic FW use, especially in large urban areas. New regulations limiting the release of such effluents into waterways and into the sea in coastal regions (e.g. the Barcelona agreement), and implementation of tighter environmental regulations, favour the sustainable reuse of TE as an attractive water source for irrigated agriculture, especially in arid and semi-arid regions. The initial positive reports deemed TE a safe alternative water source for irrigation that could even present some benefits in terms of higher yields or lower fertilizer application amounts resulting from the enrichment of TE in nutrients and organic matter.

However, this seemingly simple and attractive water resource has its challenges. The negative effect of TE on soil properties and on yields was not obvious in the first few years of TE application. Evidence from research suggests that long-term use of TE (15 years) for irrigation resulted in the degradation of several physical and hydraulic properties of a clay-rich soil. The deterioration in soil properties further resulted in a significant decrease of Avocado and Citrus yields over the years (Figure 1 and Figure 3).

Some of the risks associated with TE irrigation include higher concentrations of salts (especially sodium, Na+), and of organic compounds. The combination of these ingredients increases the exchangeable sodium percentage (ESP) of irrigated soils, thereby affecting their wettability, and contributes to a deterioration of their physical and hydraulic properties. These changes affect the fluxes in the soil profile (infiltration, drainage, evaporation and gas diffusion), and consequently, the water availability for plants.

Scientific Publication
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