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Optimal aquifer dewatering schemes for excavation of collector line

Groundwater flow modeling and optimization techniques are used jointly to determine the optimal dewatering system design for a trench type excavation (with 3,000 m total length) to be opened below the groundwater table in the Aksaray Organized Industrial District, Aksaray, Turkey. Four dewatering systems are simulated, optimized, and compared to choose the best system design. Two of the models are designed to minimize only the total amount of pumpage (linear programming models), while the other two explicitly account for the completion cost of pumping wells as well as the total pumpage amount (mixed-integer programming models). Steady-state and transient simulation models are linked to linear and mixed-integer optimization models using response functions. Since the aquifer is unconfined, an iterative correction procedure is applied to account for the nonlinearity of the system. Optimal solutions of the models are compared on the basis of completion time of the construction, pumpage amount, number of pumping wells, and efficiency and applicability of the system in practice. Results show that the transient mixed-integer programming model depicts the most favorable solution with respect to the number of wells required, the completion time of construction, and the total volume of water pumped.