RESTORING NEBRASKA'S RAINWATER BASINS? SEPARATING LONG-TERM AEOLIAN INFLUENCES FROM EROSION AND DEPOSITION IN AN AGRICULTURAL SETTING

Prior work of multiple investigators, including Kuzila, Mason, Jacobs, Miao and Zanner documents a history of multiple loess deposits beginning in the mid-early Wisconsin and continuing into the Holocene in central Nebraska, U.S.A. The Basins, oval oriented wetland depressions, are of great importance to migrating shorebirds, cranes, ducks, and geese using the North American Central Flyway As such, land managers and landowners in many cases are proposing to excavate these basins because it is assumed that water that ponds in them in spring is much reduced in area and volume because sediments have eroded from the surrounding farmed fields and partially filled the basins. Mineralogical and particle-size data collected by Kuzila from a study of the basins strongly suggests two loesses underlie the Basins and that that the sediment they are proposing to remove consists mostly of the ~9,000 year old Bignell Loess documented by Kuzila, Mason, and Miao, and that they are misinterpreting the Brady Paleosol as the presettlement surface. This interpretation is supported by recent investigations of Geiss and Zanner that are exploring magnetic and morphological properties of soils formed in loess on stable uplands across the width of Nebraska. Further studies are planned that will include coring transects crossing the basins, magnetic and mineralogical analyses, soil chemical and physical properties, and detailed studies of basin watershed hydrology and sediment transport potentials, and age control using radiocarbon dating ,OSL, and radioisotope measurements.