Accelerated sedimentation in southern Minnesota

European settlement of the Upper Mississippi Valley brought about accelerated erosion and sedimentation, which depleted soil fertility, destroyed property, and polluted water. This dissertation studied erosion and sedimentation and how these human-induced changes affected the fluvial sediment budgets of three drainage basins in southern Minnesota: Beaver Creek in Houston County, Hay Creek in Goodhue County, and Indian Creek in Blue Earth County.;The storage and delivery parts of the sediment budgets were compared to isolate the factors that caused differences in the quantities and distribution of sedimentation. I found that 48 to 70 percent of all historically eroded sediment remains stored in upland draws and in major floodplains of two fifth-order watersheds in southeastern Minnesota. In a third-order watershed in southcentral Minnesota, however, 17 percent of all historically eroded sediment lies in the main floodplains, and all other sediment has been transported out of the system. Differences in land use, geomorphology, and soil texture contribute to variations in these sediment budgets. Sediment distribution in Beaver Creek and Hay Creek watersheds was modeled using regression analysis. Floodplain width proved to be the factor that explained the most variance of sediment distribution in these watersheds. More research is needed to further model human-induced sediment flux in drainage basins.;The first part of this study assessed soil surveys, the best available data source on sediment storage. Data sampled in the field were compared with data derived from soil surveys. I found that three soil surveys of this region were not adequate sources to accurately assess historical sedimentation. Next, I intensively sampled three watersheds and extensively sampled other watersheds to document the quantity, distribution, and chronology of accelerated erosion and sedimentation in three areas of southern Minnesota. For the three main watersheds, sediment budgets of soil erosion, sediment storage, and sediment delivery were developed from field calculations and model estimates. I found that accelerated erosion started within a decade of the European settlement in the 1850s, increased with the expansion of agriculture to the 1870s, and remained high until soil conservation practices spread throughout this region in the 1930s and 1940s.