Sediment transport capacity of biological soil crusts

The sediment transport capacity test of biological crust will be conducted in August 2024. We selected typical abandoned land for vegetation restoration on the Loess Plateau, and collected undisturbed soil samples of biological crusts using rectangular ring cutters by setting different combinations of algae and moss ratios (80% algae x 20% moss (T1), 60% algae x 40% moss (T2), 40% algae x 60% moss (T3), 20% algae x 80% moss (T4), and>80% moss (T5), and a bare control (T0). The size of the ring knife is set to: length x width x height=40 cm x 10 cm x 10 cm. The entire experiment measures the basic characteristics of the biological soil crust and the hydrodynamic characteristics of the slope surface, including the thickness of the biological crust, moss biomass, surface roughness, moss coverage, flow velocity, and water depth. We selected typical abandoned land for vegetation restoration on the Loess Plateau and collected undisturbed soil samples of biological crust using a rectangular ring knife. By using a variable slope test tank and setting up 6 sets of hydrodynamic conditions, for each combination of slope flow rates, as the flow rate increases, the water flow gradually cannot carry all the sediment and will accumulate. At this time, the sediment transport rate corresponding to the outlet of the tank is the maximum sediment transport rate under this hydrodynamic condition, that is, the sediment carrying capacity of the runoff. Considering that the length of the collected biological crust sample is 40cm, sediment deposition requires a certain process. After the sediment laden water flows through the crust, samples are taken every 3-5 seconds until large-scale sediment deposition occurs in the biological crust. The average sediment transport rate of all samples is calculated, which is the runoff sediment carrying capacity under the hydrodynamic conditions under the influence of the biological crust.