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This paper discusses the role of geologic structures in the occurrence of floods and how to prevent flood in the middle reaches of the Yangtze River, and gives the author's suggestion that the Luoshan Qiakou be expanded and the la...
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This paper discusses the role of geologic structures in the occurrence of floods and how to prevent flood in the middle reaches of the Yangtze River, and gives the author's suggestion that the Luoshan Qiakou be expanded and the land reclaimed from Dongting Lake be returned to the lake in compliance with the law of geology.
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摘要 :
The middle reaches of the Yangtze River were the key areas of central China emphasized in many strategic plans.It was also an important ecological and fragile area,because there are many wetlands,lakes,rivers and soil erosion area...
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The middle reaches of the Yangtze River were the key areas of central China emphasized in many strategic plans.It was also an important ecological and fragile area,because there are many wetlands,lakes,rivers and soil erosion area.And it linked the ecological fragile upper reaches of the Yangtze River with the most developed Yangtze River Delta in China.It is urgent to figure out the key industries,key areas and key ecological and environmental problems for the strategic environmental assessment of the middle reaches of the Yangtze River.The important regions consisted of the economic key region,the planning key region,the ecological key region,and the fragile ecological region.The key industries consisted of the ones contributed to economic growth,or affecting the environment,or preferred by the local government.Besides,the ecological and environmental problems involved the water environment,the atmosphere environment,and the ecological environment.The key regions were identified through word frequency statistics of many plans by ROST Word Parser.And it was spatially overlaid by ArcGIS9.2.The key industries were calculated based on the economic statistics data,the environmental pollution census and the word frequency statistics.Based on SCI-EXPANDED,CPCI-S,CCR-EXPANDED,IC database and Chinese CNKI periodical database,the ecological and environmental problems of the middle reaches of the Yangtze River were analyzed by Citespace software according to the keywords and abstract of every paper.The results show that the important regions of the middle reaches of the Yangtze River concentrated in the central urban region,along the river and lake,surrounding mountains,and the wetland.The equipment manufacturing,chemical industry,mining industry,energy supply industry,food industry,textile and garment industry were the key industries need to be focused on.The urgent ecological and environmental problems in the middle reaches of the Yangtze River were the water environment pollution,water ecosystem,heavy metal pollution,soil and wetlands destruction,organic pollution and biodiversity decrease issues..
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The simplicity of Topography-based hydrological model (TOPMODEL),as a way of reflecting the topographic controls on soil water storage and runoff generation,has become more attractive and morepopular for land surface process study...
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The simplicity of Topography-based hydrological model (TOPMODEL),as a way of reflecting the topographic controls on soil water storage and runoff generation,has become more attractive and morepopular for land surface process study since digital elevation models (DEMs) have become widely available.In this paper,the effect of the topography index on soil water storage distribution,which is the key to TOPMODEL,is explained.Then a simple water cycle model for estimating other components of the surface water cycle is developed,which is implemented into the TOPMODEL to integrate the water cycle of the catchment.Using the output of a DEM from 100 m × 100 m resolution data and a single flow direction algorithm,the index distribution function is calculated for a catchment (around 2500 km2 )in the upper reaches of the Yangtze River under different channel initiation thresholds.Finally,the daily and monthly rainfall-runoff response from 1960 to 1987 for the catchment is simulated with the TOPMODEL coupled with the simple water cycle model.
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摘要 :
The sediment load and river sedimentation of the upper reaches of Yangtze River has been undergoing constant changes as complex landform, large mountain area and plentiful precipitation make the drainage area of Yangtze River very...
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The sediment load and river sedimentation of the upper reaches of Yangtze River has been undergoing constant changes as complex landform, large mountain area and plentiful precipitation make the drainage area of Yangtze River very vulnerable to water erosion and gravity erosion. Through analyzing the hydrological and sediment load statistics recorded by major hydrological stations along Yangtze River since 1950s, and editing the accumulation graph of annual runoff volume and annual sediment load, we find out that the suspended-sediment of Yangtze river has been decreasing year by year in Wulong Hydrological Station on Wujiang River, Beibei Hydrological Station on Jialingjiang River, Lijiawan Hydrological Station on Tuojiang River and Gaochang Hydrological Station on Minjiang River, Yichang Hydrological Station, Cuntan Hydrological Station along Yangtze River mainstream share the same experience too. But the statistics obtained at Pingshan Hydrological Station on Jinshajiang River shows the sediment load there has increased. Taking ecological construction, hydraulic engineering construction and precipitation changes into consideration, the thesis analyses the causes for the sediment load decrease of Jialingjiang River, Tuojiang River, Minjiang River and Wujiang River and provides us both scientific foundation for further study of river sediment changes of the upper reaches of Yangtze River, and measures to control river sedimentation.
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The contribution of areal precipitation of the catchment from Cuntan to Yichang (Three Gorges area)to eight flood peaks of the Upper Yangtze River (the upper reaches of the Yangtze River) is diagnosed for 1998 flood season. A rain...
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The contribution of areal precipitation of the catchment from Cuntan to Yichang (Three Gorges area)to eight flood peaks of the Upper Yangtze River (the upper reaches of the Yangtze River) is diagnosed for 1998 flood season. A rainfall-runoff model is employed to simulate runoffs of this catchment. Comparison of observed and simulated runoffs shows that the rainfall-runoff model has a good capability to simulate the runoff over a large-scale river and the results describe the eight flood peaks very well Forecast results are closely associated with the sensitivity of the model to rainfall and the calibration processes. Other reasons leading to simulation errors are further discussed.
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摘要 :
The contribution of areal precipitation of the catchment from Cuntan to Yichang (Three Gorges area)to eight flood peaks of the Upper Yangtze River (the upper reaches of the Yangtze River) is diagnosed for 1998 flood season. A rain...
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The contribution of areal precipitation of the catchment from Cuntan to Yichang (Three Gorges area)to eight flood peaks of the Upper Yangtze River (the upper reaches of the Yangtze River) is diagnosed for 1998 flood season. A rainfall-runoff model is employed to simulate runoffs of this catchment. Comparison of observed and simulated runoffs shows that the rainfall-runoff model has a good capability to simulate the runoff over a large-scale river and the results describe the eight flood peaks very well Forecast results are closely associated with the sensitivity of the model to rainfall and the calibration processes. Other reasons leading to simulation errors are further discussed.
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摘要 :
For deep foundation pit dewatering in the Yangtze River Delta, it is easy to make a dramatic decrease of the underground water level surrounding the dewatering area and cause land subsidence and geologic disasters. In this work, a...
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For deep foundation pit dewatering in the Yangtze River Delta, it is easy to make a dramatic decrease of the underground water level surrounding the dewatering area and cause land subsidence and geologic disasters. In this work, a three-dimensional finite element simulation method was applied in the forth subway of Dongjiadu tunnel repair foundation pit dewatering in Shanghai. In order to control the decrease of the underground water level around the foundation pit, the foundation pit dewatering method was used to design the optimization project of dewatering ,which was simulated under these conditions that the aquifers deposited layer by layer, the bottom of the aquifers went deep to 144.45 m, the retaining wall of foundation pit shield went deep to 65 m, the filters of the extraction wells were located between 44 m to 59 m, the water level in the deep foundation pit was decreased by 34 m, and the maximum decrease of water level outside the foundation pit was 3 m. It is shown that the optimization project and the practical case are consistent with each other. Accordingly, the three-dimensional finite element numerical simulation is the basic theory of optimization design of engineering structures of dewatering in deep foundation pit in such areas.
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A stalagmite in Qingjiang, Hubei, has yielded the records of hydrogen and oxygen as well as carbon isotopic changes and provided a climate history of 9000 years. The hydrogen iso-topic ratio in fluid inclusions and the oxygen isot...
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A stalagmite in Qingjiang, Hubei, has yielded the records of hydrogen and oxygen as well as carbon isotopic changes and provided a climate history of 9000 years. The hydrogen iso-topic ratio in fluid inclusions and the oxygen isotopic ratio in stalagmite calcite are controlled by meteoric water, which is in response to ambient temperature or precipitation amount. The carbon isotopic ratio, sensitive to the nature of vegetation, also can be used to reconstruct the climate history. The carbon-14 and U-series dated stalagmite records reveal that climate oscillated in the middle reach of Yangtze river over the past 9000 years:(1) 9.0-6.5 kaBP, a cooler and more humid condition; (2) 6.5-4.0 kaBP,with warmer and drier weather; (3) 4.0-2.0 kaBP, cold weather with heavy precipitation, and (4)2.0 kaBP to present, tendency to be warmer and drier.
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