Evolving optimal management strategies are essential for the sustainable development of water resources. A coupled simulation-optimization model that links the simulation and optimization models internally through a response matrix approach is developed for the conjunctive use of groundwater and surface water in meeting irrigation water demand and municipal water supply, while ensuring groundwater sustainability and maintaining environmental flow in river. It incorporates the stream-aquifer interactions, and the aquifer response matrix is generated from a numerical groundwater model. The optimization model is solved by using MATLAB. The developed model has been applied to the Hormat-Golina valley alluvial stream-aquifer system, Ethiopia, and the optimal pumping schedules were obtained for the existing 43 wells under two different scenarios representing with and without restrictions on stream flow depletion, and satisfying the physical, operational and managerial constraints arising due to hydrological configuration, sustainability and ecological services. The study reveals that the total annual optimal pumping is reduced by 19.75 % due to restrictions on stream flow depletion. It is observed that the groundwater pumping from the aquifer has a significant effect on the stream flow depletion and the optimal conjunctive water use plays a great role in preventing groundwater depletion caused by the extensive pumping for various purposes. The groundwater contribution in optimal conjunctive water use is very high having a value of 92 % because of limited capacity of canal. The findings would be useful to the planners and decision makers for ensuring long-term water sustainability.

不断发展的最佳管理策略对于水资源的可持续发展至关重要。开发了一种耦合模拟优化模型，该模型通过响应矩阵方法在内部将模拟和优化模型联系在一起，用于地下水和地表水的联合使用，以满足灌溉用水和市政供水的需求，同时确保地下水的可持续性和维持河流的环境流量。它包含了流—水层相互作用，而水层响应矩阵是从一个数值地下水模型生成的。通过使用MATLAB求解优化模型。该开发的模型已应用于埃塞俄比亚Hormat-Golina山谷冲积水-含水层系统，并在两种不同的情况下获得了现有43口井的最佳抽水时间表，分别代表了对水流枯竭的限制和不受限制，并满足了由于水文配置，可持续性和生态服务而产生的物理，操作和管理上的限制。研究表明，由于水流枯竭的限制，年度最佳总抽水量减少了19.75％。可以看出，从含水层中抽出的地下水对水流的消耗有显着影响，最佳的混合用水对防止因各种目的的大量抽水而引起的地下水的消耗起着重要的作用。由于运河的能力有限，地下水在最佳混合用水中的贡献非常高，其值为92％。