Trend and attribution analysis of water and sediment variations in sandy rivers

Human activities and climate change have led to significant changes in the flow and sediment of sandy rivers in northern China. The key work to reveal the changes of river water and sediment conditions is to quantitatively study the changes of precipitation, water and soil conservation in river basins, and the effect of reservoirs on sediment containment. Taking the Yongding River as a case study, we analyze the changing trend of the water and sediment into the Yongding River and find that their amount has greatly decreased. In particular, the sediment yield has decreased by more than 90% and its trend has changed, and the turning point occurred in the 1980s. Based on the statistical data analysis model, the influences of human activities on the sediment inflow of the Guanting Reservoir were quantitatively evaluated. The results show that sand retention of the upper cascade reservoirs is the main reason for the sharp reduction in sediment loads, but the sand retention effect of reservoirs has a certain time limit. Water and soil conservation played a vital role in the sediment loads reduction during the present stage. The present studies may provide insights into understanding the integrated reclamation of the river basin.

Transform the Land, Train the Youth: Water and Soil Conservation Teams and State-Induced Migration in mid-1960s China

Beginning in 1964, the PRC party-state orchestrated the resettlement of thousands of young people from cities to erosion-prone areas in China's Loess Plateau to form “water and soil conservation teams” (shuitu baochi zhuanyedui). Although their ostensible mission was to limit erosion by building terraces and planting trees, documents related to conservation teams emphasized their capacity to thoroughly reform urban youth while mobilizing them to do the work of remaking the environment. Provincial and county archives, along with fieldwork conducted at the site of one water and soil conservation team in Shaanxi province's Baishui county, indicate that conservation teams did not realize either of these objectives. Due to urban youth's inexperience with agriculture and conservation, they did little to promote environmental management. At the same time, unruly teenagers who migrated to the countryside to join conservation teams, as well as the cadres who oversaw them, continued to engage in transgressive behavior.

Soil erosion and its prevention measures during the construction period of underground engineering: a case study in the city Shanghai, China

<p><strong>Abstract: </strong>As a huge metropolis, the highly intensive development and utilization of underground space in Shanghai has become the distinct trend of urban construction. Combined research among more than 100 industrial and civil construction projects in the city finds that soil erosion during the construction of underground works accounts for a significant proportion (50%~60%) of the totality of soil erosion or degradation. In order to further promote the precise management and control of water and soil conservation in the procedure of construction engineering projects, this paper analyzes the relationship between foundation pit supporting measures and water and soil conservation results in typical underground engineering examples. Through summing up the high frequency risk points of water and soil loss caused by underground engineering of housing construction projects in Shanghai, several positive methods for preventing and controlling water and soil erosion could be contributed correspondingly for the future work, such as pretreatment of the drilling caving of bored piles, and making full use of the soil produced by underground excavation.</p><p><strong>Key words: </strong>underground engineering; risk analysis; water and soil conservation measures</p>

Soil - Water Loss and Measures Measure composition of Overhead Power Transmission Lines in Hilly area

The disturbance characteristics of power transmission line projects are long distance, scattered disturbances, large differences in natural conditions, and diverse types and strengths of soil erosion. These two points are the key to soil and water conservation, Including that identifying the main controlling factors of soil erosion in each construction disturbance area, and adapting measures to local conditions, and setting up water and soil conservation measures for disasters are power transmission lines in hilly areas. This paper took a specific project as an example, analyzed and evaluated the characteristics of water and soil erosion in the project and optimizes the configuration of measures, in order to provide a reference for the arrangement of water and soil conservation measures in the construction of similar projects.