Using Soil Properties and Terrain Attributes to Determine Landslide Potential in Southern Indiana Landscapes.

Landslides have significant and detrimental effects on sloping areas, which include the destruction of homes and communities, loss of agricultural land, water contamination, and sedimentation in rivers and reservoirs. The objective of this research was to examine hilly landscapes in southern Indiana to identify terrain attributes and soil properties that lead to mass movement in natural conditions. The goal of this research is to provide data for the Soil Survey to use as criteria for developing mass movement indices to incorporate into interpretations. Several landslides that occurred within the past 10 years were identified. Soil examinations were made to record the soil depth, texture and bedrock parent material. Terrain attributes of slope, curvature and topographical wetness index were also determined using a 1.5 m resolution DEM. The results indicate that thicker soil mantles will likely develop on slopes of minimal curvature, and thinner soils will develop on slopes of strong curvature.  A combination of slope inclination and soil depth must be great enough for failure to occur.  The rate of soil formation in an area has much to do with its underlying bedrock parent material. Threshold angles in areas prone to landsliding vary from location to location due to their dependence on other contributing factors.  From the data in this study, the threshold angles with the greatest potential for landslides occur within the range of 40-70%.  The conclusions of this research indicate that landslide potential may be related to soils and terrain attributes in much the same way the five soil forming factors are reflected in the soils chemical and physical properties which include the properties of soil depth, bedrock geology, infiltration and slope.