Contribution to the improvement of irrigation efficiency in earth seguias in the Small and Medium Hydraulic perimeters in Morocco

The objective of this article is to perform a series of measurements to determine the water distribution efficiency and seepage losses, in earthen channels in two small and medium-scale irrigation systems situated in Chichaoua and Errachidia regions. The work also consisted of an analysis of representative soil samples taken from each earthen channel. The measurements concerned 5 channels in the irrigation district of Jorf (Tafilalet) and 3 in the Upper Chichaoua irrigation district. The water distribution efficiency measure-ments were made on the basis of the inflow-outflow method. The discharge measurements were carried out by means of a current meter that can be used for measuring the flow velocities in different wetted areas of the earthen channels. The results of measurements showed that the seepage losses in the two earthen channels of the Chichaoua irrigation system vary on average between 35 and 48%, while in the Jorf irrigated area, the seepage losses tests revealed water losses ranging from 36 to 67 %. The difference between the maximum percentages of the recorded losses (48 % and 67 %) is due to the differences in soil texture of the earthen channels in the two areas. These soils are characterized by a predominance of sand in the case of Jorf and silt in Chichaoua.

Keywords: Irrigation, water distribution efficiency, seepage losses, water losses, earthen channels, discharge measurements.