Geophysical Data Collected in the Des Moines River, Beaver Creek, and the Des Moines River Floodplain, Des Moines, Iowa, 2018

A suite of geophysical methods was used along the Des Moines River, Beaver Creek, and in the Des Moines River floodplain in Des Moines, Iowa to support the hydrogeologic characterization of the alluvial aquifer associated with the river. The aquifer consists of sands and gravels underlain by weathered shale bedrock. Groundwater from the aquifer along with surface water sources are used for municipal drinking water for the City of Des Moines and surrounding communities. The raw data provided in this data release are minimally processed to filter out erroneous measurements. Data provided in this data release includes continuous resistivity profiling (CRP) and continuous seismic profiling (CSP) that were collected concurrently, electrical resistivity tomography (ERT) profiles, and horizontal-to-vertical spectral ratio (HVSR) passive seismic measurements. The CRP and ERT measure the electrical properties of the subsurface, which can be related to stratigraphic layers. The CRP, ERT, CSP, and HVSR can be used to estimate depth to bedrock. Collectively, the suite of methods can help characterize the subsurface by mapping the extent of the sand and gravel aquifer and bedrock topography.

本次研究采用一套地球物理方法，沿着美国艾奥瓦州得梅因市的得梅因河、比弗溪及得梅因河漫滩开展工作，以对与该河流相关的冲积含水层进行水文地质特征表征。该含水层由砂和砾石组成，其下伏为风化页岩基岩。该含水层抽取的地下水与地表水一同作为得梅因市及周边社区的市政饮用水水源。本次数据发布包中提供的原始数据仅经过最小程度处理，以剔除错误测量值。本次发布的数据包含同步采集的连续电阻率剖面（continuous resistivity profiling, CRP）与连续地震剖面（continuous seismic profiling, CSP）数据、电阻率层析成像（electrical resistivity tomography, ERT）剖面数据，以及水平向-垂向频谱比（horizontal-to-vertical spectral ratio, HVSR）被动地震测量数据。CRP与ERT可测量地下介质的电性特征，该特征与地层展布存在关联。CRP、ERT、CSP及HVSR均可用于估算基岩埋深。综合上述整套方法，可通过绘制砂、砾石含水层的分布范围与基岩地形，实现对地下区域的特征表征。