Sediment transport capacity is one of the key parameters in river sediment dynamics. New formulas for fractional and total transport capacity for nonuniform sediment were established and are presented in this paper, based on energy equilibrium and the fact that flow resistance decreases as sediment concentration increases. As this study shows, the transport capacities for a single fraction and total sediment are logarithmic functions of the sediment transport parameter (STP). The proposed formulas based on logarithmic law have many advantages: (1) the critical velocity for suspension of nonuniform sediment is innately embodied with simple form in the logarithmic formulas; (2) the interaction between different size particles was considered in settling velocity for any fraction of nonuniform sediment and the mean settling velocity for nonuniform sediment is equal to the geometric average of settling velocities for a sediment fraction; and (3) the formulas have the same form for fractional and total transport capacity and self-adaptability to uniform sediment. The logarithmic law was verified against laboratory and field data, and was found to perform better than power law. The derived critical velocity for suspension with interaction between nonuniform particles taken into account in the fractional and total critical velocity for suspension was also tested by using laboratory data, and it performs quite well for a wide range of particle diameters despite its simple form. The logarithmic law appropriately depicts the whole suspension process from initiation to transport and thus provides insight into the suspended motion of nonuniform sediment.

The tidal asymmetry under the action of sea level rise in Hangzhou Bay. Coastlines dominated by the tide are not only directly affected by the rise of the mean sea level but also by the tidal dynamics. The computational domain of the hydrodynamic model covers the entire Hangzhou Bay and takes into account the feedback between the tidal motion and the erodible bottom. Its main application fields include: the simulation of different sea level rise (SLR) rates, the interaction between tidal duration and skewness and the interaction between tidal range and astronomical tide. The results on tidal asymmetry in Hangzhou Bay is a systematic process consisting of four aspects: Firstly, the tide increase, which is affected by the sea level rise, is between 25% and 50%. Secondly, the value of the sea level rise is about two times the added value of the tidal range, and the tidal range increased to the left side of the tidal wave propagation direction, which accelerated the propagation velocity. Thirdly, the sea level rise amplified the M₂ tidal amplitude and delayed the M₂ tidal phase in the inner bay, which reduced about 50%. Finally, the change of the tidal range caused by tide level had the same magnitude as the change caused by the mean sea level rise. The purpose of this study was to emphasize the importance of the predictions of the response area affected by tidal asymmetry based on the action of the sea level rise in Hangzhou Bay.

Based on the flow continuity formula, resistance formula, sediment transport capacity formula and width-depth ratio relationship, the hydraulic geometry relationship and theory of equilibrium water depth for a branching river are established and are suitable for arbitrary section shape. The ratio of cross-sectional area of a distributary channel and the main stream is a power function of its bifurcation ratio with an exponent of 6/7. This was applied to a 12.5 m deep-water channel of the Yangtze River (the North Passage, Fujiangsha Waterway and Shiyezhou Waterway). The reliability of the equilibrium water depth was verified and the construction effect of the channel regulation project was predicted. The results show that the regulation project has achieved certain results on the whole, but some waterways still cannot meet the requirement of 12.5 m navigation depth. It is necessary to adjust the layout of the regulation project and focus on increasing the bifurcation ratio and reducing the flow resistance so as to increase the maximum equilibrium water depth.

The complete mitochondrial genome of the Cyprinodontiformes fish Poropanchax normani was studied in this study. The size of the entire mitochondrial genome was 16,878 bp, and the total length of the encoding sequence was 11,435 bp, accounting for 67.75%, encoding 3800 amino acids in total. Genome base compositions were: A was 27.30%, C was 28.30%, G was 16.17%, and T was 28.23%. ND2 and CO1 started with GTG, and other protein-coding genes started with ATG. ND1, ND2, and ND3 ended with TAG, respectively, CO2 and ND4 ended with a single T, and other PCGS ended with TAA. The ribosomal RNA lengths of 12S and 16S were 950 bp and 1690 bp, respectively. The control area (D-loop) was 1194 bp in size and ranged from 15,685 to 16,878 bp. It showed negative GC skew value (–0.2728) and negative AT skewness (–0.0168). Phylogenetic analysis showed that P. normani was most closely related to Xenotoca eiseni. The complete sequence of the mitochondrial genome will provide a new perspective for classification and help to draw a more complete picture of species diversity within the Cyprinodontiformes.

The classification of Badidae family based on morphology has been revised several times, but data on complete mitogenome are scarce, the complete mitochondrial genome of the Badidae fish Dario dario was characterized for the first time in the present study. The whole mitogenome was 16,830 bp in size and consisted of 13 protein-coding genes, 22 tRNAs, two rRNAs genes, a control region and origin of light-strand replication. The proportion of coding sequences with a total length of 11,431 bp was 67.92%, which encoded 3800 amino acids. The genome composition was highly A + T biased (58.12%), and exhibited a negative AT-skew (–0.0045) and GC-skew (–0.2347). All protein-coding genes started with ATG except for GTG in CO1, while stopped with the standard TAN codons or a single T. The control region (D-loop) ranging from 15,658 bp to 16,830 bp was 1173 bp in size. Phylogenetic analysis showed that D. dario was most closely related to Badis badis. The complete mitochondrial genome sequence provided new insight into taxonomic classification, and a more complex picture of species diversity within the Anabantiformes.