Impacts of Floods on Organic Carbon Concentrations in Alluvial Soils along Hydrological Gradients Using a Digital Elevation Model (DEM)

This study examines the spatial distribution of the organic carbon found in alluvial soils affected by successive floods. In flood zones, very little is known of the processes associated with the development of soils subjected to frequent flooding, in particular with respect to the accumulation of litter and organic carbon concentrations. The aim of this study is to better understand the distribution of organic carbon based on various hydrological gradients associated with flood recurrence. A digital elevation model was developed from LIDAR data to assess the microtopography of the site, and further delineate floodplains and no-flood zones. Various soil properties were considered in addition to organic carbon, such as pH, soil bulk density, litter, drainage, and topographic levels (elevation). The results show that the soils in the frequent-flood zones (FFz, recurrence of 0–20 years) have significantly less total organic carbon than the soils in the no-flood zones (NFz) and the moderate flood zones (MFz, 20–100 years). Average values obtained for the surface horizons (0–20 cm) vary by 1.74% ̆ 0.85% (FFz), 3.34% ̆ 1.09% (MFz) and 3.54% ̆ 1.77% (NFz), respectively. The absence of ground litter in the frequent flood zones helps decrease the input of organic matter in the surface horizons and progressively results in soil depletion.