T105 Geologic Maps and Their Derivatives (Posters)

Monday, 23 September 2024
8:00 AM - 5:30 PM
Hall D

CHARACTERIZING ALLUVIAL FANS FROM CROWLEY’S RIDGE USING GEOLOGIC MAPPING AND GEOPHYSICS TO IDENTIFY POTENTIAL ZONES OF ENHANCED AQUIFER RECHARGE

Paper number: T105-21
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Aquifer depletion is a significant problem in the United States, particularly for the Mississippi River Valley Alluvial Aquifer (MRVAA) in the Mississippi Embayment, where years of intense agricultural practices have led to water extraction rates that are among the highest in the country. These large water withdrawals have resulted in the formation of a large cone of depression on the MRVAA potentiometric surface southwest of Jonesboro, just west of Crowley’s Ridge. The continued decline in the potentiometric surface has caused many shallow municipal wells to run dry, and one study indicates that some areas of the MRVAA will become depleted by 2050 if current usage rates are maintained. Mitigation practices to slow the depletion of groundwater storage in the region include infiltration basins, surface recharge, and deep injection, but these are costly and have had limited success. This is partly due to a relatively thick overlying clay cap forming a confining layer.

Preliminary research in Mississippi indicates that coarse-grained on the alluvial plain may be zones that can facilitate enhanced aquifer recharge. Crowley’s Ridge is a ~240 km long, 1 to 5 km wide fault block that rises 35 to 170 m above the alluvial plain of the Mississippi embayment. The ridge contrasts sharply with the surrounding flat alluvial plain and is covered with a thick Neogene gravel cap overlain by Quaternary loess. Erosion on the ridge has created many large, coarse-grained alluvial fans that spread onto the alluvial plain. If the fans are sedimentologically connected to the MRVAA sediments, they could be well suited for managed aquifer recharge because they lack a confining cap. This research is using drilling, field mapping, and geophysics to characterize alluvial fans south of Jonesboro, Arkansas, to evaluate their potential for surface recharge of the alluvial aquifer.

Keywords: Alluvial Aquifer, Geophysics, Arkansas, Recharge, Crowley’s Ridge

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-405500

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