Establishing a model of conjunctive regulation of surface water and groundwater in the arid regions

•A conjunctive model which using the large system decomposition-coordination method was established to regulate surface water and groundwater allocations in an arid river basin in northwest China.•The model is to optimise the structure of the water supply system in space and time, and to promote reasonable development and efficient use of the limited water resources in arid river basin.•The model of conjunctive regulation of surface water and groundwater provides an effective tool for a more reasonable exploitation and utilization of limited water resources in the river basin.•Specifically, it can be applied to find regional fair, and coordinated solutions for problems of serious water shortages and within-basin water use competition in arid inland river basins.•The model can also be used to effectively control the groundwater levels and to make reasonable allocations of available water resources, so that the spatial and temporal differences in water resources in arid inland areas can be reduced, and optimal allocation and efficient use of water resources can be achieved.

A conjunctive model was established to regulate surface water and groundwater allocations in an arid river basin in northwest China. In the model, water data for the current year was used to calculate the optimal water resources allocation in the basin for a future year. Results showed that the current water resources were sufficient to meet the highest priority water needs (daily life, industry, ecological environment), but there was insufficient water to meet the needs of arable agriculture, including irrigation, in its current form. The model results highlight the need for reduced groundwater exploitation, agricultural planning and protection of the ecological environment.