Optimal Groundwater Quantity Management for Land Subsidence Control

Abstract

Groundwater overpumping could cause serious land subsidence. Although groundwater management models have been widely applied to obtain optimal pumping strategies for land subsidence control, most of them have not explicitly incorporated the land subsidence into model’s constraints. This study presented a groundwater management model explicitly considering land subsidence. To quantify the relation between land subsidence and drawdown, the one-dimensional consolidation equation was adopted which simultaneously accounts for the elastic and inelastic compaction due to pumping. Based on the response matrix technique along with one-dimensional consolidation equation, a groundwater quantity management model was developed which enables the determination of maximum total pumpage subject that the land subsidence do not exceed the allowable value. The developed management model was non-smooth optimization problem. To improve the solution efficiency, the non-smooth optimization was transferred into mixed integer linear programming (MILP) by introducing the binary variables. A hypothetical example was utilized to demonstrate the applicability of developed model. The results indicated that the land subsidence should be explicitly incorporated into model’s constraints; otherwise the optimal total pumpage might be overestimated. Moreover, the simultaneous consideration of elastic and inelastic compaction in groundwater management was important, especially when the difference between initial head and preconsolidation head was significant.