Estimating sediment yield from a small urban catchment of a heterogeneous structure

Abstract

Small urban areas, due to their specificity (high anthroposphere, multiple forms of land use, variable drainage conditions), are often overlooked in studies on soil erosion and sediment transport that predominantly focus on a large scale. The sediment yield from such small urban areas may greatly vary depending, for example, on the state of the land development. Therefore, its proper estimation is crucial for water resources management, improving urban runoff quality or designing and maintaining local retention ponds. In this study, two different approaches were applied to estimate sediment yield from a small urban catchment of Służew Creek, located in Warsaw, Poland. While the first was based on direct hydrological measurements and field samples, the second (indirect) used various empirical formulas to predict bed load transport (local formula of Skibiński) in the stream channel and the suspended sediment delivery from the catchment (USLE equation, Build‐up/Wash‐off model). The sediment load established according to the direct approach equals 714 Mg/year, of which 83 Mg/year results from the bed load transport and 631 Mg/year comes from the suspended sediment transport. The total sediment load calculated according to the indirect approach equals 579 Mg/year. The relative difference in loads calculated with these two methods is about 20%. This paper combines various established methods into a novel composite analysis of sediment yield. The methodology presented in this study may support the estimation of sediment load in small urban catchments with a heterogenous land use structure. Hence, it may support urban planning and water resources management in such small catchments.

Urbanization and Suspended Sediment Transport Dynamics: A Comparative Study of Watersheds with Varying Degree of Urbanization Using Concentration-Discharge Hysteresis

“…Excessive flux of suspended sediments has deleterious effects on river ecosystems, including degradation of stream habitat. , In contrast, a lack of suspended sediment flux results in “hungry water”, which can lead to bank erosion, channel widening and incision, and modification of the riverine habitat. − Although alteration in sediment regime and geomorphology are among the primary symptoms of urban stream syndrome and have been documented in earlier studies, , research on sediment transport in urban watersheds remains limited. A significant portion of the limited studies of sediment in urban watersheds − has investigated the issue of increased suspended sediment yield, first documented by Wolman . The understanding of the sources, timing, mechanism, and pathways of fine sediment delivery in built-out urban watersheds remains underexplored.…”