Determination of sediment delivery ratio in draining systems

Abstract

Determination of the amount of sediment that outflows from the draining system via ditches, based on the known intensity of erosion processes in the catchments of this system, requires the calculation of a sediment delivery ratio (SDR). As a result of investigations into erosion and sediment transport processes, conducted in the main R-ditch of the Łączany draining system, the assessment of the applicability of the SDR has been conducted. as determined according to empirical formulas. The SDR was established using nine models, developed on the basis of studies of sediment runoff from river catchments. The obtained results of calculations were compared with the SDR, defined as the soil loss quotient (E) in the partial sub-catchments calculated using the USLE method, and the mean annual sediment transport (T), calculated on the basis of the bathometric measurements. For this purpose, the catchment area of the draining system was divided into seven sub-catchments, closed by measuring cross-sections, in which measurements of the suspended sediment concentrations were conducted. It was found that the calculated SDR values are significantly smaller than the SDR values determined according to the nine formulas. Using the tested empirical formulas, the calculated sediment transport in the draining system would be several to several dozen times larger than the actual sediment transport. Only in the case of the Williams and Brendt formula and the Williams formula, SDR values are similar to those obtained from calculations based on a given average annual intensity of erosion, and average annual sediment transport.

Keywords

• USLE
• SDR
• erosion
• sediment
• suspended sediment concentration