In this study, a series of ecological porous spur-dikes are arranged in an experiment channel to simulate a real field drainage ditch. The inside and outside flow fields of spur-dikes are determined by numerical simul...In this study, a series of ecological porous spur-dikes are arranged in an experiment channel to simulate a real field drainage ditch. The inside and outside flow fields of spur-dikes are determined by numerical simulations and experimental methods. An Ammonia-Nitrogen（NH3-N） degradation evaluation model is built to calculate the pollution removal rate by coupling with the inner flow field of the porous spur-dikes. The variations of the total pollutant removal rate in the channel are discussed in terms of different porosities and gap distances between spur-dikes and inlet flow velocities. It is indicated that a reasonable parameter matching of the porosity and the gap distance with the flow velocity of the ditch can bring about a satisfactory purification efficiency with a small delivery quantity of ecological porous materials.展开更多
With the deepening of research in the tectonic evolution and stress fields of China in Meso-Cenozoic, some aspects of the Previous conclusion about the tectonogeomorphology of China are found to be open to question. T...With the deepening of research in the tectonic evolution and stress fields of China in Meso-Cenozoic, some aspects of the Previous conclusion about the tectonogeomorphology of China are found to be open to question. The author considers that the Sichuanian stage (135-52 Ma ) is the embryonic stage for forming the recent landform in eastern China;the appearance of the mountain ranges and drainage basin areas trending in east-west are the results of the north - south directional extension during the North Sinian stage(52 - 23.3 Ma );the formation of five mega - Step landforms from the Qinghai - Xizang Plateau to Pacific ocean and the seafloor spreading basins in the eastern margin of Asian continent as well as the l- up of drainage systems of both Yangtze and Yellow rivers are related to the northward compression, cast-west trending extension and the isostatic compensation of crust during Himalayan Stage (23.3-0.73 Ma ). Through the above three Stages of tectonic processes, a framework of landform of China finally took shape in the main.展开更多
This paper focuses on the analysis of the effects of groundwater tablecontrol under different irrigation water amounts on the water and salinity balance and on cropyield. Two experimental areas, the Pingluo and Huinon...This paper focuses on the analysis of the effects of groundwater tablecontrol under different irrigation water amounts on the water and salinity balance and on cropyield. Two experimental areas, the Pingluo and Huinong experimental sites, were selected to collectthe required data. The agro-hydrological model Soil-Water-Atmosphere-Plant (SWAP) was used toanalyse the water flows and salt transport processes for different groundwater levels and irrigationscenarios. Six scenarios, which resulted from different groundwater table regimes combined withdifferent irrigation amounts, were simulated. The results show that high ground-water tables due tothe excessive irrigation are the main cause of the large amount of drainage water and low cropyield; reducing irrigation water without a lower groundwater table will not lead to a largereduction of the drainage water, and will reduce the crop yield even more; to lower the groundwatertable is a good measure to control the drainage water and increase crop yield.展开更多
基金Project supported by the National Science Funds for Creative Research Groups of China(Grant No.51421006)the National Major Projects of Water Pollution Control and Management Technology(No.2017ZX07204003)+2 种基金the National Key Plan for Research and Development of China(Grant 2016YFC0502203)the Key Program of National Natural Science Foundation of China(Grant No.91647206)the Qing Lan Project of Jiangsu Province
文摘In this study, a series of ecological porous spur-dikes are arranged in an experiment channel to simulate a real field drainage ditch. The inside and outside flow fields of spur-dikes are determined by numerical simulations and experimental methods. An Ammonia-Nitrogen（NH3-N） degradation evaluation model is built to calculate the pollution removal rate by coupling with the inner flow field of the porous spur-dikes. The variations of the total pollutant removal rate in the channel are discussed in terms of different porosities and gap distances between spur-dikes and inlet flow velocities. It is indicated that a reasonable parameter matching of the porosity and the gap distance with the flow velocity of the ditch can bring about a satisfactory purification efficiency with a small delivery quantity of ecological porous materials.
文摘With the deepening of research in the tectonic evolution and stress fields of China in Meso-Cenozoic, some aspects of the Previous conclusion about the tectonogeomorphology of China are found to be open to question. The author considers that the Sichuanian stage (135-52 Ma ) is the embryonic stage for forming the recent landform in eastern China;the appearance of the mountain ranges and drainage basin areas trending in east-west are the results of the north - south directional extension during the North Sinian stage(52 - 23.3 Ma );the formation of five mega - Step landforms from the Qinghai - Xizang Plateau to Pacific ocean and the seafloor spreading basins in the eastern margin of Asian continent as well as the l- up of drainage systems of both Yangtze and Yellow rivers are related to the northward compression, cast-west trending extension and the isostatic compensation of crust during Himalayan Stage (23.3-0.73 Ma ). Through the above three Stages of tectonic processes, a framework of landform of China finally took shape in the main.
基金the National Natural Science Foundation of China.(Grant No:50239090)
文摘This paper focuses on the analysis of the effects of groundwater tablecontrol under different irrigation water amounts on the water and salinity balance and on cropyield. Two experimental areas, the Pingluo and Huinong experimental sites, were selected to collectthe required data. The agro-hydrological model Soil-Water-Atmosphere-Plant (SWAP) was used toanalyse the water flows and salt transport processes for different groundwater levels and irrigationscenarios. Six scenarios, which resulted from different groundwater table regimes combined withdifferent irrigation amounts, were simulated. The results show that high ground-water tables due tothe excessive irrigation are the main cause of the large amount of drainage water and low cropyield; reducing irrigation water without a lower groundwater table will not lead to a largereduction of the drainage water, and will reduce the crop yield even more; to lower the groundwatertable is a good measure to control the drainage water and increase crop yield.
