Seismic reflection imaging of hydrostratigraphic facies in Boise: A tale of three scales

We have acquired, processed and interpreted seismic reflection data from the Boise Valley at three scales to help build a hydrostratigraphic model for regional groundwater studies and to better understand the hydrostratigraphic significance of seismic boundaries. We use existing industry seismic reflection data to identify the structural and stratigraphic framework of the western Snake River Plain, a normal-fault bounded basin that contains more than 2 km of Neogene and younger sediments. To directly tie structure and stratigraphy to water well lithology and geophysical logs, we have acquired seismic reflection data throughout Boise to image near-surface sediments, where prograding delta and fluvial sediments control groundwater flow. To correlate seismic boundaries to hydrologic properties in Boise, we have also acquired seismic reflection data from a highly characterized wellfield. We find the seismic boundaries directly correspond to bulk changes in porosity at this site. Seismic reflection data from these three scales better define basin morphology and help map discrete hydrostratigraphic units necessary to understand hydraulic connectivity, groundwater flow directions, and aquifer capacity in the Boise Valley.