A Bilevel Multiobjective Model for Optimal Allocation of Water Resources in the Punjab Province of Pakistan

In this study, a simple but efficient bilevel multiobjective model (BLMOM) has been formulated for the optimal allocation of available water (AW) among competing water users. Upper-level decision makers (DMs), being the leader in the hierarchy (i.e., river authorities), allocate AW to lower-level DMs (i.e., canal authorities) based on equity and stability, whereas lower-level DMs allocate AW among competing users based on two single- and one multiobjective functions. The first objective function (OF1) maximizes the satisfaction rate (SR) of various water users, whereas the second objective function (OF2) maximizes the net economic benefits (NEB). The multiobjective function (OF12) maximizes the combined effect of the first two single objectives. The multiobjective function has been solved by using the simultaneous compromise constraint (SICCON) technique which creates a compromise between single-objective functions. The model was applied at Taunsa Barrage, Pakistan, for the optimal allocation of AW. Various scenarios were analyzed by varying priorities assigned to different objective functions and water users to evaluate the model applicability under various conditions. When OF1 was considered, maximum SR of 61% was achieved. In case of priority given to OF2, maximum NEB of 77 million USD was attained. However, in the case of OF12, both SR and NEB were maximized, whereas wheat, cotton, sugarcane, rice, onion and sunflower water users attained NEB of 14.36, 5.03, 22.96, 27.85, 1.34 and 0.13 million USD, respectively, with overall NEB of 72 million USD against satisfaction rate of 52%.