In the process of groundwater numerical simulation, groundwaterwithdrawal is always treated as certain sink item for long time.
地下水数值模拟过程中，人工开采量大都被当作确定项处理。
2
Therefore, the land subsidence can be alleviated by limiting the withdrawal volume even if groundwaterwithdrawal is not stopped.
说明即使不停止开采地下水，只要将地下水的采取量控制在一定的范围，也可以大大减轻地面沉降。
3
However, due to lack of accurate statistic data, there exists uncertainty in determining groundwaterwithdrawal, especially groundwaterwithdrawal for agricultural irrigation.