Abstract
The frequent droughts in recent years have made agricultural production unstable in Morocco. However, there are few studies on monitoring and assessment of water delivery management on lateral and tertiary canal level in the irrigation districts. Therefore, this study aimed to clarify water distribution in Beni Amir irrigation district, one of the large irrigation districts in Morocco and discuss the water-saving potential through improving water distribution. Water distribution records of all fields with areas were collected for 4 years from 2016 to 2019. Monthly precipitation data was collected for 48 years from the dam meteorological station. To clarify the water distribution in the study district, the amount of irrigation per unit area, the amount of water per irrigation, and the irrigation frequency by lateral and tertiary canals and fields were statistically analyzed during mid irrigation seasons (Apr. - Sep.). Monthly reference evapotranspiration was calculated by FAO-Penman Monteith method, and the balance of water supply and demand of the study area was analyzed. The results showed that large variations in amount of water allocation among lateral canals were observed in drought years while it was small in normal years. However, this does not mean that the upstream in the study area took more water. The different ratio of area under priority crops among the canals is a major reason for this. In addition, even in wet years, enough amount of water has not been supplied to meet the demand and this situation has not changed significantly over the past decade. Regarding the analysis on water-saving potential, 4.4 - 6.6 Mm3 of water could be saved by shortening the irrigation time unit from 1 hour to 30 or 15 minutes. This enhanced water distribution practice also contributes to improve the more equitable water distribution. Even if it is difficult to shorten the time unit for irrigation, water for distribution management could be saved by making the field area an integral multiple of 1.2 ha through merging and readjustment of fields.
