Conference paper

Appeared in: MODSIM2011, 19th International Congress on Modelling and Simulation: Sustaining our future: understanding and living with uncertainty

Editor list: Chan, F; Marinova, D; Anderssen, RS

Publication year: 2011

Pages: 829-835

ISBN: 978-0-9872143-1-7

URL: http://mssanz.org.au/modsim2011/B1/multsch.pdf

Conference: 19th International Congress on Modelling and Simulation (MODSIM2011)

Abstract: 
The largest share of total water resources utilization is required by the agricultural sector with an average of 80% on the global scale and 90% in Saudi Arabia. In contrast to rain fed agriculture, water use in Saudi Arabia is directly linked to irrigation as rainfall only contributes to a minor proportion of crop water requirements. Non-renewable fossil aquifers provide the origin of this irrigation water. Reserves are localized at depths between 150 and 1500 m. Furthermore, the salinisation of agriculture fields puts an additional pressure on fresh water resources in Saudi Arabia. Maintaining soil quality generally requires salt leaching for which additional fresh water resources are being used. On a global scale up to 50% of soils in semi-arid and arid environments are affected by salinization, indicating that the indirect water use for leaching significantly contributes to total water resources use in irrigation based agricultural production systems. We therefore developed the Water footprint Assessment Framework (WAF) for estimating the fate of water use in agricultural production systems. WAF enables the spatial explicit calculation of the internal water footprint of a region or nation, considering all water resources required to produce food and feed, including green (precipitation), blue (irrigation) and grey (de-salinization) water. WAF is based on the virtual water concept originally introduced by Allan in the 1990s, and further developed to the water footprint concept by Hoekstra in the past years. Equipped with a graphical user interface WAF calculates crop water requirement according to the Food and Agricultural Organization FAO56 crop water guidelines. User defined parameters allow to set crop types, irrigation efficiencies, salinity of irrigation water or depression of yields due to salinization. We further implemented the WAF scenario manager to rapidly investigate the effect of introducing different cropping regimes on site specific water resources. The WAF database provides soil and climate information as well as data on yields to calculate crop water requirements for each spatial entity. Apart from using public avaialable data provided by FAO on soils, climate and yields that only allow the estimation of the water footprint of an entire nation, WAF can be spatially adapted to more site specific data by extending the WAF database, as shown in this case study. Here we present results of such a spatially more differentiated approach of estimating the internal water footprint for Saudi Arabia. Using the scenario manager we present how WAF can also be applied to improve the nation's water footprint. Irrigation management and changes in agricultural crops scenarios are presented to show potential improvements of the internal agricultural Saudi Arabian water footprint. The spatially explicit approach facilitates to delineate locations where improvements in the water footprint will allow the most effective reduction of water losses in the country. Average water footprints of cereals, vegetables, fodder crops and fruits are 4725 m(3) t(-1), 761 m(3) t(-1), 1887 m(3) t(-1) and 4753 m(3) t(-1), respectively. The surprisingly low water footprint of vegetables can be explained by the high yields and very efficient water resource utilization, despite the generally high total water use for vegetable production. Fodder crops, dominated by Alfalfa production, give high yields as well.Fruits in contrast are dominated by date production, a palm that is relatively inefficient with respect to water use efficiency. In addition it is quite salt sensible and therefore requires large amounts of gray water for leaching soils. The national water footprint of the agriculture sector has been calculated in relation to varying irrigation settings, which refer to salt concentration of the applied irrigation water, irrigation method and yield potential. The mean national water footprint of Saudi Arabia amounts to 23.5 km(3) yr(-1) (2004-2008) assuming nationwide ineffective sprinkler and surface irrigation with efficiencies of around 50-60% and average salt concentrations of irrigation water of 4 dS m(-1). This estimate by WAF is in good agreement with published values of around 21 km(3) yr(-1) for the year 2006. However, by increasing irrigation efficiency up to 85% for example by promoting drip irrigation, and reducing salt concentrations down to 1.2 dS m(-1), the internal water footprint of Saudi Arabian agricultural sector could almost be halved to 13.5 km(3) yr(-1).

Harvard Citation style: Multsch, S., Alrumaikhani, Y., Alharbi, O., Frede, H. and Breuer, L. (2011) Internal water footprint assessment of Saudi Arabia using the Water footprint Assessment Framework (WAF), in Chan, F., Marinova, D. and Anderssen, R. (eds.) MODSIM2011, 19th International Congress on Modelling and Simulation: Sustaining our future: understanding and living with uncertainty. Modelling and Simulation Society of Australia and New Zealand. pp. 829-835. http://mssanz.org.au/modsim2011/B1/multsch.pdf

APA Citation style: Multsch, S., Alrumaikhani, Y., Alharbi, O., Frede, H., & Breuer, L. (2011). Internal water footprint assessment of Saudi Arabia using the Water footprint Assessment Framework (WAF). In Chan, F., Marinova, D., & Anderssen, R. (Eds.), MODSIM2011, 19th International Congress on Modelling and Simulation: Sustaining our future: understanding and living with uncertainty. (pp. 829-835). Modelling and Simulation Society of Australia and New Zealand. http://mssanz.org.au/modsim2011/B1/multsch.pdf