Soil-landscape relationships at the lower reaches of a watershed at Bear Creek near Oak Ridge, Tennessee

The watersheds at Bear Creek, Oak Ridge, TN, have similar soil-landscape re lationships. The lower reaches of many of these watersheds consist of headw ater riparian wetlands situated between sloping non-wetland upland zones. T he objectives of this study are to examine the effects of (i) slops and geo morphic processes, (ii) human impacts, and (iii) particular characteristics of soils and saprolite that may effect drainage and water movement in the wetlands and adjacent landscapes in one of these watersheds. A transect was run from west to east in a hydrological monitored area at the lower reache s of a watershed on Bear Creek. This transect extended from a steep side sl ope position across a floodplain, a terrace. acid a shoulder slope, On the upland positions of the Nolichucky Shale, mass wasting, overland flow and s oil creep currently inhibit soil formation on the steep side slope position where a Typic Dystrudept is present, while soil stability on the shoulder slope has resulted in the formation of a well-developed Typic Hapludult. In these soils, argillic horizons occur above C horizons on less sloping grad ients in comparison to steeper slopes, which have Bw horizons over Cr (sapr olite) material. A riparian wetland area occupies the floodplain section, w here a Typic Endoaquept is characterized by poorly drained conditions that led to the development of redoximorphic features (mottling). gleying, organ ic matter accumulation, and minimal development of subsurface horizons. A t hin colluvial deposit overlies a thick well developed Aquic Hapludalf that formed in alluvial sediments on the terrace position. The colluvial deposit from the adjacent shoulder slope is thought to result from soil creep and anthropogenic erosion caused by past cultivation practices. Runoff from the adjacent sloping landscape and groundwater from the adjacent wetland area perhaps contribute to the somewhat poorly drained conditions of this profil e. Perched watertables occur in upland positions due to dense saprolite and clay plugging in the shallow zones of the saprolite. However, no redoximor phic features are observed in the soil on the side slope due to high runoff . Remnants of the underlying shale saprolite. which occur as small discolor ed zones resembling mottles, are also present. The soils in the study have a CEC of < 10 cmol kg(-1). silt loam textures and Fe-d values of 0.5-4.3%. These soils are also mainly acidic and low in total carbon. (C) 2001 Elsevi er Science B.V. All rights reserved.