Bulk Density of Soils at Floodplain Restoration Sites


  • Evan Bletz, Environmental Science, Franklin & Marshall College

Faculty Mentor(s)

  • Shreeram Inamdar, Plant and Soil Sciences, University of Delaware


In recent years, the northeast U.S. has invested significant time and money into restoring floodplains, as degraded floodplains lead to heavier floods in urban areas, as well as poorer water quality and a weakened river ecosystem. However, little to no monitoring is performed after restoration efforts have been completed, especially for soil health.  Soil is vital to the success of floodplains, as healthy soils house the microbes and fungi that enable stable development of local plant and animal species in riparian zones.  One key metric is bulk density (BD), a measure of soil’s compaction, which can determine how efficiently soil can uptake water and nutrients.  It is hypothesized that heavy machinery used during restorations may potentially negatively affect BD.  To observe this, soil samples were taken beneath vegetation in both restored and unrestored sections of twelve floodplain restoration sites and one control group, a mostly untouched and undamaged natural floodplain, using segments of copper tubes to maintain natural compaction.  These soils were then weighed both wet and dry, and by subtracting out core weight, the dry soil rate and BD were determined.  Gravimetric water content (GWC), volumetric water content (VWC), and soil porosity (SP) were also calculated to measure water quantity compared to soil quantity.  Preliminary results suggest that BD and SP values don’t significantly differ between restored and unrestored sections of floodplains, but GWC and VWC rates were significantly higher in restored sections.  The control group was significantly different from the other floodplains, restored and unrestored, in all recorded metrics, with lower BD and higher VWC, GWC, and SP.  The data suggests that floodplain restoration do have some clear benefits in terms of water retention, but have room to improve for soil compaction, and could shape the way restorations are conducted in the future.