The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield bas...The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus（SDM） in the study area decreased from 7,767.4 t/（km^2·a） in 1951–1969 to 980.5 t/（km^2·a） in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/（km^2·a） is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/（km^2·a）.展开更多
The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production pe...The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production per capita(physical capital),and areas of fenced pasture,livestock shelter,grassland rodent control and planted grassland(physical capital) as proxy indicators of livelihood promotion,livelihood provision,and livelihood protection respectively.By developing a correlation model between pastoralists' livelihood protection and improvement,we found that(1) there is a statistically significant correlation between the pastoralists' livelihood protection and promotion;(2) based on the maximum effect of pastoralists' livelihood promotion and provision,there is a benchmark in the effect of the intervention intensity of livelihood capital(grassland resource protection) on livelihood improvement;(3) on basis of two indicators,i.e.net income per capita and meat production per capita,the reasonable scales of fenced pasture,livestock shelter and planted grassland are less than 843,860 and 46 thousand hectares(hm2) per year respectively.With the marginal effect of livelihood protection,moderately decreased areas of fenced pasture and planted grassland,and increased area of livestock shelter is a critical to ensure pastoralist's livelihood sustainability.展开更多
The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group （RNG） k-ε model was developed to simulate the flow in the re...The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group （RNG） k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-e model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning＇s roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases.展开更多
In order to consume the Yellow River sediment as much as possible and improve the longterm stability of the Yellow River, Yellow River sediment was utilized as the main raw material to produce a composite material. Ca...In order to consume the Yellow River sediment as much as possible and improve the longterm stability of the Yellow River, Yellow River sediment was utilized as the main raw material to produce a composite material. Ca(OH)_2 was used as alkali-activator to activate the active SiO_2 and Al_2O_3 compositions in Yellow River sediment. 10 wt% slag was added into the mixture to further improve the strength of the composites. The effect of activity rate of the Yellow River sediment and dosage of Ca(OH) _2 on the compressive strength of the Yellow River sediment-slag composite material at different curing ages was researched. XRD, SEM/EDS, light microscope and FTIR were used to further explore the products and the microstructure of the composite material. Results showed that the active ratio of sediment had a great influence on the compressive strength of specimen. In addition, the compressive strength of specimen increased with the increase of Ca(OH)_2dosage and curing age. When the dosage of Ca(OH)_2 was more than 5 wt% as well as the curing age reached 90 days, the compressive strength of the composite material could meet the engineering requirement. In the alkali-activated process, the main product was hydrated calcium silicate(C-S-H) gel, which filled up the gaps among the sediment particles and decreased the porosity of the specimen. Moreover, the CaCO_3 produced by the carbonization of the C-S-H gel and excess Ca(OH)_2 also played a role on the strength.展开更多
The Yellow River has a vast catchment area and historically it is the mother river of the Chinese nation. Now it serves as one of the main theatres for the on-going national campaign to develop China's western... The Yellow River has a vast catchment area and historically it is the mother river of the Chinese nation. Now it serves as one of the main theatres for the on-going national campaign to develop China's western hinterland.……展开更多
THE Yellow River is the second longest river in China and called the cradle of Chinese civilization. With a drainage area totaling 750,000 square kilometers, it runs 5,464 kilometers through nine provinces and autonom...THE Yellow River is the second longest river in China and called the cradle of Chinese civilization. With a drainage area totaling 750,000 square kilometers, it runs 5,464 kilometers through nine provinces and autonomous regions before emptying into the Bohai Sea.展开更多
基金funded by the Major Programs of the Chinese Academy of Sciences (KZZD-EW-04-03-04)the National Science-technology Support Plan Project (2006BAD09B10)the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-EW-406)
文摘The well-documented decrease in the discharge of sediment into the Yellow River has attracted considerable attention in recent years. The present study analyzed the spatial and temporal variation of sediment yield based on data from 46 hydrological stations in the sediment-rich region of the Yellow River from 1955 to 2010. The results showed that since 1970 sediment yield in the region has clearly decreased at different rates in the 45 sub-areas controlled by hydrological stations. The decrease in sediment yield was closely related to the intensity and extent of soil erosion control measures and rainstorms that occurred in different periods and sub-areas. The average sediment delivery modulus（SDM） in the study area decreased from 7,767.4 t/（km^2·a） in 1951–1969 to 980.5 t/（km^2·a） in 2000–2010. Our study suggested that 65.5% of the study area with the SDM below 1,000 t/（km^2·a） is still necessary to control soil deterioration caused by erosion, and soil erosion control measures should be further strengthened in the areas with the SDM above 1,000 t/（km^2·a）.
基金Funding for this research was provided by the National Basic Research Program of China (Grant No. 2010CB 951704)
文摘The interaction among different livelihood capitals is a key to generate a deeper understanding of the livelihood sustainability.In this paper,we use net income per capita(economic capital),meat and milk production per capita(physical capital),and areas of fenced pasture,livestock shelter,grassland rodent control and planted grassland(physical capital) as proxy indicators of livelihood promotion,livelihood provision,and livelihood protection respectively.By developing a correlation model between pastoralists' livelihood protection and improvement,we found that(1) there is a statistically significant correlation between the pastoralists' livelihood protection and promotion;(2) based on the maximum effect of pastoralists' livelihood promotion and provision,there is a benchmark in the effect of the intervention intensity of livelihood capital(grassland resource protection) on livelihood improvement;(3) on basis of two indicators,i.e.net income per capita and meat production per capita,the reasonable scales of fenced pasture,livestock shelter and planted grassland are less than 843,860 and 46 thousand hectares(hm2) per year respectively.With the marginal effect of livelihood protection,moderately decreased areas of fenced pasture and planted grassland,and increased area of livestock shelter is a critical to ensure pastoralist's livelihood sustainability.
基金supported by the National Natural Science Foundation of China(Grants No.11361002 and 91230111)the Natural Science Foundation of Ningxia,China(Grant No.NZ13086)+1 种基金the Project of Beifang University of Nationalities,China(Grant No.2012XZK05)the Foreign Expert Project of Beifang University of Nationalities,China,and the Visiting Scholar Foundation of State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,China(Grant No.2013A011)
文摘The upper reach of the Yellow River from Daliushu to Shapotou consists of five bends and has complex topography. A two-dimensional Re-Normalisation Group （RNG） k-ε model was developed to simulate the flow in the reach. In order to take the circulation currents in the bends into account, the momentum equations were improved by adding an additional source term. Comparison of the numerical simulation with field measurements indicates that the improved two-dimensional depth-averaged RNG k-e model can improve the accuracy of the numerical simulation. A rapid adaptive algorithm was constructed, which can automatically adjust Manning＇s roughness coefficient in different parts of the study river reach. As a result, not only can the trial computation time be significantly shortened, but the accuracy of the numerical simulation can also be greatly improved. Comparison of the simulated and measured water surface slopes for four typical cases shows that the longitudinal and transverse slopes of the water surface increase with the average velocity upstream. In addition, comparison was made between the positions of the talweg and the main streamline, which coincide for most of the study river reach. However, deviations between the positions of the talweg and the main streamline were found at the junction of two bends, at the position where the river width suddenly decreases or increases.
基金Funded by the National Natural Science Foundation of China(Nos.51578108,51878116,51809109)the Fundamental Research Fund for the Central Universities(No.DUT18ZD219)National Key R&D Program of China(No.2017YFC0504506)
文摘In order to consume the Yellow River sediment as much as possible and improve the longterm stability of the Yellow River, Yellow River sediment was utilized as the main raw material to produce a composite material. Ca(OH)_2 was used as alkali-activator to activate the active SiO_2 and Al_2O_3 compositions in Yellow River sediment. 10 wt% slag was added into the mixture to further improve the strength of the composites. The effect of activity rate of the Yellow River sediment and dosage of Ca(OH) _2 on the compressive strength of the Yellow River sediment-slag composite material at different curing ages was researched. XRD, SEM/EDS, light microscope and FTIR were used to further explore the products and the microstructure of the composite material. Results showed that the active ratio of sediment had a great influence on the compressive strength of specimen. In addition, the compressive strength of specimen increased with the increase of Ca(OH)_2dosage and curing age. When the dosage of Ca(OH)_2 was more than 5 wt% as well as the curing age reached 90 days, the compressive strength of the composite material could meet the engineering requirement. In the alkali-activated process, the main product was hydrated calcium silicate(C-S-H) gel, which filled up the gaps among the sediment particles and decreased the porosity of the specimen. Moreover, the CaCO_3 produced by the carbonization of the C-S-H gel and excess Ca(OH)_2 also played a role on the strength.
文摘 The Yellow River has a vast catchment area and historically it is the mother river of the Chinese nation. Now it serves as one of the main theatres for the on-going national campaign to develop China's western hinterland.……
文摘THE Yellow River is the second longest river in China and called the cradle of Chinese civilization. With a drainage area totaling 750,000 square kilometers, it runs 5,464 kilometers through nine provinces and autonomous regions before emptying into the Bohai Sea.
