Dynamics of suspended sediment concentration, flow discharge and sediment particle size interdependency to identify sediment source

Abstract

Spatiotemporal behavior of sediment yield is a key for proper watershed management. This study analyzed statistical characteristics and trends of suspended sediment concentration (SCS), flow discharge (FD) and sediment particle sizes using data from 24 gage stations scattered throughout the United States. Analysis showed significant time- and location-specific differences of these variables. The median values of SSC, FD and percentage of particle sizes smaller than 63µm (P63) for all 24 gage stations were found to be 510.236mgl−1 (right skewed), 45.406m3s−1 (left skewed) and 78.648% (right skewed), respectively. Most of the stations exhibited significant trends (P<0.001) in daily SSC (18 stations; one increasing and 17 decreasing), FD (19 stations; seven increasing and 12 decreasing), and P63 (15 stations; five increasing and 10 decreasing) as well. Further, 46% of the stations exhibited significant trends in all three variables. The wash load significantly contributed (79.085±11.343%) to sediment load recorded at the gage stations. Results of the study can be used for developing best watershed management practices which may call for local or regional planning based on natural (i.e., precipitation amount, type and erosivity, watershed area, and soil erodibility) and human-affected (i.e., land use and hydraulic structures and water resources management) factors governing the study variables.