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Sediment pollution has been one of the most serious water pollution problems in urban rivers, called the ‘autogenous pollution’, which has also caused critical ecological risk to river as well as surrounding environment. Therefore, quantitative analysis of sediment pollution is of great importance to come up with a treatment scheme. In this study, comprehensive pollution analysis of contaminants has been conducted for various vertical stratifications using 86 columnar samples with depth of 3∼4 m. Pollution assessments of organic matter, total nitrogen, total phosphorus, toxic substances and heavy metal elements were conducted. Then, the comprehensive pollution depths can be determined based on pollution assessment of each vertical layer, which shows that the maximum pollution depth can be up to 2.0 m, 3.0 m and 3.0 m for Reach A, Reach B and Reach C, respectively. The results has been used to determine the spatially changing thickness in environmental protection dredging in Maozhou River.

Groin type and vegetation in groin fields directly affect flow field, bank protection, and river evolution. Many studies focus on fixed-bed contexts, but there are few studies on the influence of riverbed changes on hydrodynamic characteristics around groins. In this study, three types of groins are investigated experimentally in fixed and mobile beds in terms of time-averaged flow characteristics, turbulence characteristics, and bed changes. In both fixed- and mobile-bed experiments, vegetation reduced erosion of the groin field and main stream. Compared with the fixed-bed experiment, the velocity in the main stream was decreased in the mobile-bed experiment, and the longitudinal turbulence intensity and lateral momentum exchange were increased. In this study, an improved three-dimensional groin group (upstream wing submerged T-shaped groin group) produced a lower sediment scouring capacity, average scour depth, and entrainment coefficient k than I-shaped and T-shaped groin groups.

Statistical analysis and geochemical approaches were exploited for the heavy metals (HMS) assessment in sediments from Beijing-Hangzhou Grand Canal. Single source (crustal) was identified using principal component analysis (PCA). Furthermore, enrichment factor (EF) denoted contaminated sites by HMS in the study area while EF value reveal minor enrichment or no anthropogenic enrichment from most sites. The anthropogenic activities that suggested to be primarily from agriculture and automobile repair discharge.

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