A study of the determination of indicators of dual control of groundwater abstraction amount and water table in northwest China: a case study of the Minqin Basin

Groundwater plays an important role in water supply, ecological factors and environmental factors in the arid and semi-arid inland river basins of Northwest China. At present, there is short of research on the determination methods of indicators of dual control of groundwater abstraction amount and water table fitting to the characteristics of the arid and semi-arid areas in northwest China. There is not enough technical support for water resource management and ecological protection in northwest China. In this study a technical scheme is set up for determining groundwater dual control management indicators in Northwest Chinato meet the demand of sustainable utilization and ecological protection of groundwater.This system design include the following steps: (1) Observation wells in the management region are divided into 3 types according to groundwater functional zone, each type of well has its upper and lower threshold, and the water level management index is composed of the selected observation wells and their thresholds. (2)Groundwater discharge by natural vegetation can be regarded as an irresistible discharge term. Based on the corrected groundwater numerical simulation model, forecast simulations under different abstraction scenarios are programmed. The abstraction scenarios that meet the water table index constraint is picked out and the extremum amounts are defined as the threshold of water amount index. The technical scheme is employed to the Minqin Basin in the lower parts of the Shiyang River for the example verification. Water level index are emerged at 26 observation wells with the upper threshold of 5.00～0.00 m and the lower threshold of 49.37～5.00 m. The calculations of 18 abstraction scenarios show that the groundwater amount index was 6 000×104 m3/a as lower threshold and 10 000×104 m3/a as the upper threshold. The actual exploitation and water table during 2012 to 2016 show that the water level index and water amount index are matching, indicating that the technical scheme is reasonable. This technical scheme can provide certain technical support for the development of dual-control management in northwest China.