USE OF STRATIGRAPHY, SEDIMENT AND SOILS TO ASSESS THE POTENTIAL FOR CONVERTING AN ABANDONED AGRICULTURAL FIELD INTO A MAN-MADE WETLAND, EVANSVILLE, INDIANA

A need to utilize property recently granted to the University of Southern Indiana yielded a plan to develop a human-made wetland. In addition to the wetland providing a location for biological and geological training, it also has potential to capture environmentally hazardous chemicals from campus housing and parking lots.

The study area sits within an underfit stream valley underlain by late Quaternary alluvium and glaciolacustrine sediments associated with the Ohio River.

The stratigraphy observed in sediment cores consists of a sand to sandy silt at a depth of 3.26 to 3.35 m overlain by 0.82 to 2.25 m of sandy silt interpreted as fluvial sediments. Overlying these fluvial sediments is a 0.82 to 2 m thick silt to clayey silt interpreted as loess-derived floodplain or colluvial sediment. Wakeland series soils developed in the upper silt are poorly drained, with Ap/Bt/C profiles extending through the silt into the uppermost part of the silty alluvium. Mottling, gleying and iron nodules are common in all cores, evidence of a fluctuating water table. Cores and GPR data confirm the location of the water table at an average of 1.5 m depth. The water table slopes gently downward from east to west before intersecting the stream channel at 1.9 m.

The main stream channel and “tributary” drainage ditches flood the field semiannually. Water currently ponds in shallow depressions during heavy rains except where the farmer dug a 0.4 m deep drainage slough. Hydraulic conductivity in the soils are poor due to the clay-rich horizons in the soil, but increases with increasing sand at depth.

Based upon the available soil, sedimentologic and hydrologic data, the area appears to be a strong candidate for developing a human-made or human-augmented natural wetland.