Abstract: According to the observation logs, precipitation, temperature monitoring and surrounding investigation, the interference events are classified in detail for the water level observation of the double wells in Ganhai to identify and eliminate interference more accurately and effectively. A preliminary technical solution is proposed for the blockage and man-made cleaning interference that occur most frequently and have the greatest impact on normal observation. The results of hydrogen and oxygen isotope analysis show that the water from two wells is recharged by atmospheric rainfall. Rainfall interference can be identified by collecting rainfall and flow data of river.