Application Study Of CSAMT Method To Survey Underground Water In Fractured Zone

Controlled Source Audio-frequency MagnetoTellurics(CSAMT)is a geophysical exploration technology that has developed rapidly in recent years.This method mainly realizes the detection of stratum by measuring the response of the artificially established electromagnetic field to the stratum.The CSAMT method has the advantages of high work efficiency,small influence of topography,high horizontal resolution,large test depth range,and high vertical resolution,and is not affected by high-resistance shielding.Based on the work of the Xiamen Urban Geological Survey Project,this paper explores the application of the CSAMT method in the detection of groundwater in the concealed fissure zone in the shallow bedrock area for the exploration of groundwater in the concealed fissure zone encountered during the survey of the emergency water source in the urban geological survey.The paper introduced the theoretical basis,detection principle and working methods of CSAMT,combined with the actual exploration tasks of the water exploration area in Xiamen Urban Geological Survey Project,analyzed the geophysical characteristics of the exploration target,and studied the CSAMT method in the detection of groundwater in the fracture zone.The actual application of its effects,through this study,draws the following conclusions:1.Groundwater in the main fissured zone in the Neicuo water source of Xiamen is mainly located in the fissure zone of the northeastern granite porphyry vein.2.The geophysical model of the detection of groundwater in the fracture zone of granite area is based on a high-resistance background,and the three-dimensional stripshaped low-resistance anomaly detection is covered by a conductive thin layer.This study shows that the use of CSAMT method to detect cracked groundwater is reasonable and effective.3.The detection profile of the CSAMT method takes into account both the shallow(<100m)fine detection and the deep(>100m)full-scale detection.The detection of buried structures in hilly terrain with complex terrain conditions has advantages that conventional electric methods cannot match.4.The work of the CSAMT method should be based on adequate geological survey work.A full understanding of the geological background and target of the survey area is a prerequisite for successful detection.The geological interpretation of the working data of the CSAMT method should be performed in conjunction with the geological background of the survey area.This is an effective way to reduce geophysical data and improve the accuracy of exploration.