Overturning stability of supported geomembrane tube for flood control

As a kind of rapid filling hydraulic structure, geomembrane tube can effectively act as flood barriers and cofferdams for flood risk management. L-shaped block is used to support geomembrane tube to prevent it from rolling. The contact force between the L-shaped block and the geomembrane tube is analyzed by using particle flow code (PFC2D) software, and the overturning stability of the L-shaped block is calculated. The relationship between the key factors and the overturning stability was established. It is found that the central angle of the L-shaped block has little influence on the overturning stability. The overturning stability decreases with the increase of the initial pumping pressure. Keeping Lw/Lb unchanged, increasing Lb will improve the overturning stability where Lw and Lb are the width and the height of the Lshaped block. Under the ultimate water level, when 1.23 Lbcr < Lw≤1.55 Lbcr, the L-shaped block is in the state of overturning stability where Lbcr is the critical height of the L-shaped block. The initial pumping pressure is less than 0.152γL, the L-shaped block is in the state of overturning stability with Lw/Lbcr =1.0 where L is the cross-sectional perimeter of the geomembrane tube and γ is the unit weight of the filling liquid, on the contrary, Lw/Lbcr must be greater than 1 to ensure its overturning stability

Revision of two species of Sinopotamon Bott, 1967 (Crustacea, Brachyura, Potamidae) endemic to China: a new combination and a new synonym

The systematics of two problematic potamid species, Sinopotamon koatenense (Rathbun, 1904) and Sinopotamon wuyiensis Li, Lin, Cheng & Tang, 1985, both originally described from the Wuyi Mountains are resolved in this study. Sinopotamon koatenense is transferred to the genus Huananpotamon Dai & Ng, 1994, as the new combination Huananpotamon koatenense comb. nov. The new combination differs from its congeners in the form of the carapace, male pleon, male first gonopod, and vulvae. Phylogenetic analyses based on mitochondrial 16S rDNA sequences support the identification of Huananpotamon koatenense comb. nov. and a redescription is also provided. In addition, S. wuyiensis is confirmed as a junior synonym of Sinopotamon fukienense Dai & Chen, 1979 based on morphological similarities and phylogenetic lineages

Optimized Nitrogen Application Increases Soil Water Extraction by Changing in-Season Maize Root Morphology and Distribution in Rainfed Farmland

The proper promotion of a deep root system is important for maize cultivation to improve water use efficiency in the arid and semi-arid Loess Plateau. Here, a field experiment was conducted to assess the effect of combined controlled release urea and normal urea on root growth and water extraction of maize in dryland fields. Maize in the combined controlled release urea and normal urea treatment had greater root systems compared to those in the normal urea treatment and no N application treatment. Compared to the urea treatment, combined controlled release urea and normal urea advanced the root length density and root weight density in the 0&ndash;10 cm soil layer at R1 stage by 30.99% and 45.03% in 2016 and by 20.54% and 19.13% in 2017. The root length density also increased at the dent stage (R5) by 52.05% and 47.75% in 2016 and 2017, and root weight density increased by 19.58% in 2016. Combined controlled release urea and normal urea promoted production of fine roots and root distribution, as well as decreased soil water storage (SWS) in the deep soil layer at the R5 stage. The grain yield was positively correlated with root length density and root weight density in the topsoil layer at the silking stage (R1) and in the whole soil profile at the R5 stage, suggesting that better root system management is helpful for increasing crop grain yield. Therefore, this work demonstrates that combined use of controlled release urea and normal urea to higher crop yields might attribute to increasing water extraction by optimizing in-season maize root morphology and distribution in the rainfed farmland of the Loess Plateau