This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS)...This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS) and wet (WS) seasons. Flow measurement was performed at 9 stations using a calibrated flow meter OTT C31. Water flow and sediment flux from 2004 to 2019 were used. Hydrodynamic forecast simulations were performed using Mann-Kendall test and ARIMA model for determination of temporal trends. Findings suggest higher values during DS for water discharge and sediment flux. Mann-Kendall test for sediment discharge trends was not significant at 95% significance level, except for the Offtake in WS. ARIMA test for the sediment discharges, at the Intake, for DS and WS, sediments were well described by the ARIMA model and gave a good result for the sediments. Good fit between the observed and the predicted ARIMA model was found. ARIMA model for sediment discharge at CIS based on AIC has a good fit for AR (p = 1), whereby, at the Intake the ARIMA p-value was 0.822 and 0.932, for WS and DS, respectively. Whilst in the Offtake, the ARIMA p-value was 0.877 and 0.893, respectively. These results can be used to improve the CIS management, both for water flow and sediment flux.展开更多
In the test, internal inlay drip irrigation pipes with different wal thicknesses or diameters （￠at 12 mm and 16 mm） were tested under varying tension forces and it was concluded that 90 N is the rational one. What...In the test, internal inlay drip irrigation pipes with different wal thicknesses or diameters （￠at 12 mm and 16 mm） were tested under varying tension forces and it was concluded that 90 N is the rational one. What’s more, the smal er drip-irrigation inner diameter, the thinner wal thickness, and the higher tension force, the lower acceptability, and the larger drip-irrigation inner diameter, the thicker wal thickness, and the lower tension force, the higher acceptability. The causes were analyzed in the research, including manufacturing technique leading to disqualifica-tion and different specifications with the same demands on techniques, and inadap-tation to tension force at 130 N.展开更多
滑坡是一种常见的地质灾害,灌溉诱发黄土滑坡失稳是常见地质灾害之一。灌溉作用不仅改变了地下水平衡,而且降低了土体的抗滑强度,从而导致黄土滑坡的发生。针对黑方台焦家崖头13号黄土滑坡,开展了灌溉作用下滑坡失稳机理的离心模型试验...滑坡是一种常见的地质灾害,灌溉诱发黄土滑坡失稳是常见地质灾害之一。灌溉作用不仅改变了地下水平衡,而且降低了土体的抗滑强度,从而导致黄土滑坡的发生。针对黑方台焦家崖头13号黄土滑坡,开展了灌溉作用下滑坡失稳机理的离心模型试验研究,揭示了黄土滑坡的变形特性、应力水平及破坏模式。离心模型的制作考虑了"粒径效应"、"尺寸效应"。离心试验结果表明:随着加载时间和离心加速度的增大,模型坡体沉降量、坡体土压力、坡体孔隙水压力均逐渐增大;坡体沉降量由坡顶至坡脚逐渐减小,最大垂直位移为33.38 mm,坡体土压力由坡顶至坡脚逐渐增大,最大土压力为320 k Pa,坡体孔隙水压力表现为坡顶>坡脚>坡体中部,最大孔隙水压力为157.08 k Pa;坡体呈现出两级破坏模式,即第一阶段的坡脚蠕动变形,坡顶压制拉裂,第二阶段的坡体剪切滑移。展开更多
文摘This study sought to forecast water flow and sediment flux in the scheme as potential contributions for improved management in the Chókwè Irrigation Scheme (CIS). Fieldwork data was collected during dry (DS) and wet (WS) seasons. Flow measurement was performed at 9 stations using a calibrated flow meter OTT C31. Water flow and sediment flux from 2004 to 2019 were used. Hydrodynamic forecast simulations were performed using Mann-Kendall test and ARIMA model for determination of temporal trends. Findings suggest higher values during DS for water discharge and sediment flux. Mann-Kendall test for sediment discharge trends was not significant at 95% significance level, except for the Offtake in WS. ARIMA test for the sediment discharges, at the Intake, for DS and WS, sediments were well described by the ARIMA model and gave a good result for the sediments. Good fit between the observed and the predicted ARIMA model was found. ARIMA model for sediment discharge at CIS based on AIC has a good fit for AR (p = 1), whereby, at the Intake the ARIMA p-value was 0.822 and 0.932, for WS and DS, respectively. Whilst in the Offtake, the ARIMA p-value was 0.877 and 0.893, respectively. These results can be used to improve the CIS management, both for water flow and sediment flux.
文摘In the test, internal inlay drip irrigation pipes with different wal thicknesses or diameters （￠at 12 mm and 16 mm） were tested under varying tension forces and it was concluded that 90 N is the rational one. What’s more, the smal er drip-irrigation inner diameter, the thinner wal thickness, and the higher tension force, the lower acceptability, and the larger drip-irrigation inner diameter, the thicker wal thickness, and the lower tension force, the higher acceptability. The causes were analyzed in the research, including manufacturing technique leading to disqualifica-tion and different specifications with the same demands on techniques, and inadap-tation to tension force at 130 N.
文摘滑坡是一种常见的地质灾害,灌溉诱发黄土滑坡失稳是常见地质灾害之一。灌溉作用不仅改变了地下水平衡,而且降低了土体的抗滑强度,从而导致黄土滑坡的发生。针对黑方台焦家崖头13号黄土滑坡,开展了灌溉作用下滑坡失稳机理的离心模型试验研究,揭示了黄土滑坡的变形特性、应力水平及破坏模式。离心模型的制作考虑了"粒径效应"、"尺寸效应"。离心试验结果表明:随着加载时间和离心加速度的增大,模型坡体沉降量、坡体土压力、坡体孔隙水压力均逐渐增大;坡体沉降量由坡顶至坡脚逐渐减小,最大垂直位移为33.38 mm,坡体土压力由坡顶至坡脚逐渐增大,最大土压力为320 k Pa,坡体孔隙水压力表现为坡顶>坡脚>坡体中部,最大孔隙水压力为157.08 k Pa;坡体呈现出两级破坏模式,即第一阶段的坡脚蠕动变形,坡顶压制拉裂,第二阶段的坡体剪切滑移。
