Optimal cropping pattern for limited water supply: A case study in Lebanon

The problem of optimal allocation of a limited water supply, for irrigation of several crops in the same area, is addressed in this article. Both intr a-seasonal and inter-seasonal competition for water, among various crops, i s considered. A Linear Programming mathematical model was developed to dete rmine optimum water allocation. The main objective of this optimization mod el was to choose the optimal cropping pattern that satisfies the existing c limatic, agronomic, economic, and land and water availability constraints f or a selected pilot study area in Ghazzah, in the South Bekaa region of Leb anon. Two different scenarios, as well as another irrigation distribution s cheme already planned for the pilot area, were compared to the current prac tice. Different conditions and restrictions on crop production and utilizat ion of land resources were tested within the two scenarios. Results reveal that neither the current cropping pattern nor that of the planned distribut ion scheme is optimal, and that they should be replaced. The lowest net ret urn is achieved with the current cropping pattern. Higher profits could be obtained in both tested scenarios due to the introduction of new crops to t he area. The recommended scenario is the one having the highest net benefit to initial investment cost ratio.