IWRA Executive Office

abstract 622

Assessment of sustainable agriculture in the irrigated perimeter of Tadla, Morocco using the CRIWAR strategy module

Author(s): Rob A.L. Kselik, Marinus G. Bos, Ali Hammani, Aziz Bellouti
1)Corresponding main author: R.A.L. Kselik Alterra, Wageningen UR P.O. Box 47, 6700 AA Wageningen, The Netherlands Phone + 31 317 486469 Fax + 31 317 419000 Email rob.kselik@wur.nl 2) Marinus G. Bos International Institute for Geo-Information

Keyword(s): sustainable agriculture, irrigation, groundwater, management, depleted fraction

Article:

Poster:

Session: OS4e Infrastructure

AbstractTo ensure sustainable agriculture in

an irrigated area, the conditions under which crops grow, should remain stable over a prolonged period. For crops

production, actual evapotranspiration should be close to the potential evapotranspiration. At the same time

degradation of the soil (salt accumulation), mining of the groundwater aquifer and the negative influence of drainage

water on the downstream environment should be avoided. Water management therefore should balance the need of

water for agriculture and the need for a sustainable environment.

The CRIWAR strategy module is a tool,

which evaluates ETa from the gross irrigated area and the annual fluctuation of the groundwater table under this area.

It expands on the concept that the part water in an area not being consumed or discharged (groundwater flow or

surface drainage) will be stored in the area. A major part of this non-depleted part will be stored as groundwater.

This results to a rising groundwater table and potential salinity in semi-arid regions. If water consumption is relatively

high, water storage can be negative and the groundwater table drops.
Management information for the

groundwater table is obtained through the depleted fraction (Molden 1997, Bastiaanssen et al 2001). The depleted

fraction is defined as the ratio of the actual evapotranspiration, over the sum of precipitation and irrigation water, the

latter parameters being the total inflow into the gross irrigated area. It gives information on the rate of change with

which water is stored in the area (Bos, 2004) and thus the rate of change of the groundwater table. When there is no

change in groundwater storage on a yearly basis, water consumption (ETa) in the area is sustainable from a water

balance point of view.
By managing the volume of irrigation water, the depleted fraction can be influenced and

thus the volume of water stored in the aquifer.

The CRIWAR strategy module is applied in the Tadla irrigated

perimeter in Morocco. The area is known for a long history of irrigation, which started in 1935. Before 1980

groundwater tables in the phreatic aquifer rose due to large irrigation supplies. This caused soil deterioration and the

need for an artificial drainage system. After a large drought between 1981 and 1984 and the structural decrease of

the annual rainfall since 1992, farmers started to exploit groundwater on a large scale (Hammani, 2004). Cropping

intensification and excessive groundwater subtraction have resulted in mining of the groundwater resources. If this

mining continues at the present rate the rural agriculture based economy will become non-sustainable.

Conclusions

The CRIWAR model can be used to evaluate the past and present use of the water

resources in the irrigated perimeter. It can be used as a planning tool for water managers and decision makers to

assess the impact of measures like change in cropping patterns, reallocation of water or improved efficiency. In the

Tadla perimeter the model is applied to match the crop water requirements with the surface water availability and the

allowable groundwater subtraction to ensure a sustainable use of the water

resources.

Acknowledgements

The research described in this paper is conducted in the

framework of the AquaStress project (2005-2009), an EU funded integrated project

(http://www.aquastress.net/).

References

Bastiaanssen W.G.M., Brito R.A.L., Bos M.G., Souza R.,

Cavalcanti E.B. & Bakker M.M. 2001. Low Cost Satellite Data Applied to Performance Monitoring of the Nilo

Coelho Irrigation Scheme, Brazil, Irrigation and Drainage Systems, vol. 15.1,pp. 53-79. Kluwer Academic

Publishers, Dordrecht.

Bos M.G. 2004.Using the depleted fraction to manage the groundwater table in

irrigated areas., Irrigation and Drainage Systems, vol.18, pp 201 – 209. Kluwer Academic Publishers, The

Netherlands.

Hammani A., Kuper M, Debbarh A et Bouarfa S, 2004. Evolution de l’exploitation des eaux

souterraines dans le Tadla. Actes du séminaire Euro-Méditerranéen sur la modernisation de l’Agriculture Irriguée. 19

au 21 avril 2004, Rabat, Maroc.

Molden D.J. 1997. Accounting for water use and productivity, SWIM paper

1, International Water Management Institute (IWMI), Colombo, Sri Lanka, 16 pp.

Events

The congress

Programme

Practical Infos

Assessment of sustainable agriculture in the irrigated perimeter of Tadla, Morocco using the CRIWAR strategy module