Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of China Geological Survey. In this study, we present two example sites in Ningdu County selected to demonstrate the combined hydrogeological survey, and the direct current electrical resistivity method was utilized for the present study for groundwater exploration in karst-granite distribution areas. First, a hydrogeological study was effectively used to delineate shallow severely weathered structural fissures as prospective target water-bearing beds. Then, a direct current electrical resistivity survey was used to confirm the distribution, thickness scale, and water-bearing features. The structural fractured zone whose distribution and trend were first established through hydrogeological surveys and whose development characteristics and water-richness were investigated by the direct current electrical resistivity method is the target layer for water exploration in the karst-granite rock areas. The water-bearing fracture zone shows a groove or strip-shape low resistivity anomaly and can be identified in its aquifer position according to its IP half decay time (Th), apparent polarizability (ηs), and apparent resistivity (ρs). The findings demonstrate that the above methods were successful in locating water potential areas, providing information for comparison and accurate borehole positioning. The results of the subsequent drilling and pumping tests supported the interpretation of the geophysical exploration data, and the water output from both boreholes met the objectives of this study. This groundwater search might serve as a guide for future exploration projects in similar areas.

Non-invasive geophysical exploration methods a play key role in the exploration of ore deposits. In the present study, the audio-frequency magnetotelluric (AMT) method was applied to metallic mineral exploration. The metallic mineral deposit targeted was the recently discovered super large lead–zinc deposit of the Zhugongtang mining area of Hezhang County in the northwestern Guizhou province in China. The main objectives of this study were to estimate the geoelectric strike and generate geoelectric models that estimate both the depth and distribution of resistivity structures across the deposit. To achieve the objectives, we deployed sixty-one (61) AMT survey sites with an interstation separation of 20 m on a 1280 m survey track perpendicular to the geological strike across the Zhugongtang deposit. We operated in fifty-three (53) frequencies in the range 1–10,400 Hz to record the resistivity distribution of subsurface to a depth of more than 1200 m. The results from the AMT data computations estimated the geoelectric strike that varies between NE285° and NE315°. This range of strikes suggested that structures across the deposit are oriented in the NW–SE direction. Obtained two-dimensional (2D) models elucidated a remarkably low resistivity body (<15 Ωm) at an elevation of less than 1600 m above sea level (>0.50 km depth), thus extending to great depth and were interpreted as lead–zinc mineralization. Furthermore, low resistivity (<63 Ωm) features were imaged both in superficial and deeper depths and interpreted as shale, sandstone, claystone, and silty mudstone units. Dolomite and limestone lithologies were found widely distributed with high resistivity (>1000 Ωm). Bioclastic limestone and dolomite limestone were inferred and characterized by moderate-high resistivity (>250 Ωm) and were not widely distributed. A unit of basalts was found with moderate resistivity (>63 Ωm). In addition, it was also found that regions with high number of faults tend to have low resistivity values compared to regions with a low fault number. In summary, this case study presents the results of applying an AMT approach to explore the conductivity characteristics of structures across the Zhugongtang deposit. The findings may contribute to the literature about this deposit.

The paper introduces the design and the testing of a customized multi-function waveform generator for the testing of an EM receiver. There are very few literatures considering this problem although many EM instrument owns build-in waveform generator for testing. I suggest the publishing of the manuscript if the following suggestions are considered by authors .1. This manuscript lacks essential references considering the testings of EM receiver. There are papers and patents in English and Chinese considering this problems. This problems is attacked by many Chinese authors. I just list a few of works by myself here.