oa Conjunctive Use Of Geophysical And Geological Data In The Construction Of A Broundwater-Flow Model

Geophysical survey information combined with test-hole logs<br>were used as the data base for the construction of a numerical<br>model to simulate groundwater flow and the impact of pumping on<br>part of the lower Platte River alluvial aquifer located in<br>eastern Nebraska. The hydrogeologic framework of the study area<br>was determined from the interpretation of seismic-refraction<br>data, shallow seismic-reflection profiles, and vertical<br>electrical soundings. Seismic-survey results calibrated to testhole<br>logs provided the basis to map the areal extent of the<br>complex bedrock surface beneath the study area. Results of the<br>geoelectric survey were used to map the area1 extent and<br>thickness of a near-surface, low-permeability clay unit along the<br>western margin of the Platte Valley floodplain. Geophysical data<br>were also used to estimate the bulk density and porosity of the<br>aquifer material. Utilizing all of the field data available, a<br>three-dimensional groundwater-flow model was designed to simulate<br>a two-layer system in which part of the aquifer is under confined<br>flow conditions. The model was then applied to the study area to<br>evaluate the impact of seasonal pumping schedules of a well field<br>that provides municipal water to the City of Lincoln.