モロッコにおける伝統的水利施設ハッターラの灌漑システム改善に関する研究

Abstract

The purpose of this study is to develop the measure of the improvement of the traditional irrigation system called Khettara in Morocco. There are 191 Khettara in the Tafilalet region which exists in the western Morocco. Morocco is in the north-western tip of African Continent. The farming system is remarkably different from each other between east and west regions of the Atlas Mountains. The Tafilalet region in east Morocco has a lot of poor farmers under the severe national and social condition. The farming system of the Tafilalet region depends on the groundwater through shallow well or Khettara. Using of water is the most important constraint for the agricultural development in the arid zone such as the Tafilalet region. The Khettara irrigation system has its origin in the Quanat in Iran, and it is said to be introduced by the Muslim expanded to the Morocco in the seventeenth century. Khettara water is used for potable water, livestock and domestic use at first, and used for irrigation for date palm, olive, wheat, barley, tomato, carrot, turnip, herb, etc. Khettara irrigation system has some advantages comparing with other water supply system. Discharge of Khettara is small, however perennial flow is very fare to sustain rural life and gravity flow minimizes operation cost. On the other hand, Khettara system has some problems. Khettara structure has been constructed by nothing but manpower, therefore tunnels and canals are unpaved. The structure is easy to collapse and water leakage is widely observed. Moreover continuous drought causes decrease of the Khettara flow. Water loss is also apparent in basin irrigation method which is adopted without exception in the irrigation plots of this area, and which is relatively less efficient for water saving. The measure for the improvement of irrigation system of traditional water-use facilities 'Khettara' in Morocco is able to be developed by rehabilitation of Khettara structure and using furrow irrigation in stead of basin one in this study. It is concluded that the reactivation of the agricultural sector in the Tafilaleto region is feasible. Also the furrow irrigation is appropriate to be substitute for the basin irrigation in Mauritania and other Western African countries.