Aflaj’s Irrigation Water Demand/Supply Ratio: Two Case Studies

Abstract

Due to the geographical location of Oman in an arid zone, agricultural production depends fully on irrigation. The traditional irrigation systems (Aflaj, sing. falaj) supply more than one third of water for agriculture. Falaj is defined in the context of this paper as a canal system which provides water for domestic and agricultural uses. Oman has 3,107 active Aflaj producing about 680 Mm3 of water per year. The main objective of this study was to estimate the irrigation performance of Aflaj in Oman. Falaj al-Dariz and al-Nujaid were chosen as case studies. Both Aflaj are located in an extremely arid environment, where the rainfall is low and evapotranspiration is high. The study utilized an approach to estimate the irrigation performance of Aflaj by considering the falaj as a single unit of irrigation. The irrigation demand/supply ratio (D/S) was used in the analysis as a tool of evaluation. Date palm, the dominant crop irrigated by Aflaj, was selected for the analysis. In falaj al-Dariz the date palms were slightly under irrigated on a yearly basis. On a monthly basis, in winter, the D/S was below 0.6 and in summer it was above 1.0. On the other hand, falaj al-Nujaid was supplying too much water than the date palms needed all round the year. In winter the D/S ratio was as low as 0.25. Even in summer, the D/S ratio did not much exceed 1.0.

Damage Cost of Drying of Aflaj in the Sultanate of Oman

“…Although Aflaj in Oman have persisted for hundreds of years, they are facing an unprecedented degradation in recent years as confirmed by flow measurements (Al-Ghafri, 2006;MRMEWR, 2006 (MRMWR, 2001) in 1996 has reported that more than 1,000 Aflaj out of 4,112 have dried-up Aflaj supply about 410 million m 3 /year, representing 38% of Oman's fresh water, which satisfies part of domestic and agricultural demand in scattered rural areas (Norman et al, 1997;Zekri and Al-Marshudi, 2008). Aflaj constitute an integrated environment where thousands of people live, produce, consume and trade healthy fresh products.…”

“…In fact, there is no scientific evidence of rainfall decline or change in rainfall intensity during the period 1974-2003 as shown by Kwarteng et al (2009) eliminating thus the assumption of drought being the cause of dry-up. Although several studies have been undertaken regarding Aflaj irrigation systems, water resources (Al-Ghafri, 2006) and water markets (Zekri et al, 2006), the damage caused to the rural communities due to Aflaj dryup has not been estimated. Evaluating the damages caused to communities by Aflaj dry-up helps decision makers to implement appropriate policies to remedy and/or prevent it and to support public expenditures in repairing and maintaining some of the Aflaj.…”