The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Lon...The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. How- ever, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be car- ried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that darn safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.展开更多
The simulating exactly compared with realty of ground surface to run a model is more and more highly required. In the real, terrain of the earth surface is always complicated by the natural and human made ground objec...The simulating exactly compared with realty of ground surface to run a model is more and more highly required. In the real, terrain of the earth surface is always complicated by the natural and human made ground objects. Because of limitation of collecting and storing technologies in the past time, data are usually not detailed so that the data can not be full for the simulation. Besides computing power and simulation increase more day by day, the increasing requirements more detailed of topography surface simulation is a demand. In simulated flooding phenomenon or phenomena related to energy and momentum of water flow, the linear objects of ground surface such as roads, dikes, dams, etc. need to have their vertical dimension along continuously. However, these datas have often no height information alternately, there are only discrete elevation points that are extracted from topographic maps. Consequently, the demand of a suitable method for linear objects height interpolation is necessary. This paper aims to provide a method and evaluate its accuracy to meet this requirement.展开更多
Mountains and plateaus in Southwest China contain many subalpine and alpine wetlands, with signifieant hydroecological functions. But ungauged or poorly gauged eonditions limit the study and understanding of hydrologi...Mountains and plateaus in Southwest China contain many subalpine and alpine wetlands, with signifieant hydroecological functions. But ungauged or poorly gauged eonditions limit the study and understanding of hydrological regimes of these wetland types. This study selects an ungauged subalpine wetland - Napahai in Northwest Yunnan, China - as a case for developing a practical approach to revealing its storage-area relationship of open water. A Trimble R8 GNSS （Global Navigation Satellites Systems） RTK （Real-time Kinematic system） and sonar fathometer were used to survey fine- resolution elevation data and generate a digital elevation model of the Napahai Wetland. Forty-four Landsat images from 1987 to 2Oll were collected, and the Normalized Difference Water Index was used to classify open water features in the area. The area of open water in Napahai was ealculated for each phase. With these data and a developed conceptual model, the storage of open water for each phase was estimated using ArcGIS tools. Both storage and area of open water showed significant intra-annual and inter-annual variations. In the rainy season, the monthly change of average storage of open water in Napahai showed about 1-2 months lag behind mean monthly rainfall. The storage-area relationship of open water was well fit by a power function equation （R2=0.91, n=44）. This study indicates that if detailedelevations are available for similarly ungauged subalpine wetlands in Southwest China, researchers can use this practical approach to estimate multi- temporal areas and storages and reveal the storage- area relationship of open water in the wetlands. The study provided valuable information of this ease wetland for optimizing its hydro-ecological managements and a new method to wetland researchers and managers for the hydrological study of similarly ungauged wetland complex.展开更多
Groundwater comprises a large portion of irrigation for California＇s agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the sam...Groundwater comprises a large portion of irrigation for California＇s agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the same time, contaminants from fertilizers and pesticides are infiltrating into the groundwater, becoming increasingly concentrated as water is extracted. It compared space-based observations of groundwater anomalies from California＇s San Joaquin Valley using the GRACE （gravity recovery and climate experiment） against measurements of 42 organic and inorganic chemicals from 41,667 wells in the valley from 2003 to 2010. It compared Arsenic, Boron, Cadmium, Chloride, Selenium, Trichloroethylene, and TDS （total dissolved solid） concentrations with the groundwater storage anomaly from 2003 to 2010. The results show strong correlations for groundwater depletion against increasing chloride （r2= 0.78, p 〈 0.05） and boron （r2 = 0.88, p 〈 0.05）. This indicates increasing contaminant concentrations while groundwater was depleting over the last eight years. Solubilization by complexation with Cl, CO3 and/or organic chelates may account for the increasing concentration of some heavy metals when groundwater depletion occurs. These results are the first to link space-based groundwater mass change with groundwater contaminant concentration change.展开更多
Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, a...Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, among which effectively detecting CO2 from deep underground is one of engineering problems. This paper reviews monitoring techniques currently used during CO2 injection and storage. A method developed based on measuring seismic microtremors is of main interest. This method was first successfully used to characterize a site in this paper. To explore its feasibility in C02 storage monitoring, numerical simulations were conducted to investigate detectable changes in elastic wave signatures due to injection and geological storage of CO2. It is found that, although it is effective for shallow earth profile estimation, the surface wave velocity is not sensitive to the CO2 layer physical parameter variations,especially for a thin CO2 geological storage layer in a deep underground reservoir.展开更多
文摘The basic element in any sustainable dam project is safety, which includes the following safety elements： O structural safety, dam safety monitoring, operational safety and maintenance, and emergency planning. Long-term safety primarily includes the analysis of all hazards affecting the project; that is, hazards from the natural environment, hazards from the man-made environment, and project-specific and site-specific hazards. The special features of the seismic safety of dams are discussed. Large dams were the first structures to be systematically designed against earthquakes, starting in the 1930s. How- ever, the seismic safety of older dams is unknown, as most were designed using seismic design criteria and methods of dynamic analysis that are considered obsolete today. Therefore, we need to reevaluate the seismic safety of existing dams based on current state-of-the-art practices and rehabilitate deficient dams. For large dams, a site-specific seismic hazard analysis is usually recommended. Today, large dams and the safety-relevant elements used for controlling the reservoir after a strong earthquake must be able to withstand the ground motions of a safety evaluation earthquake. The ground motion parameters can be determined either by a probabilistic or a deterministic seismic hazard analysis. During strong earthquakes, inelastic deformations may occur in a dam; therefore, the seismic analysis has to be car- ried out in the time domain. Furthermore, earthquakes create multiple seismic hazards for dams such as ground shaking, fault movements, mass movements, and others. The ground motions needed by the dam engineer are not real earthquake ground motions but models of the ground motion, which allow the safe design of dams. It must also be kept in mind that darn safety evaluations must be carried out several times during the long life of large storage dams. These features are discussed in this paper.
文摘The simulating exactly compared with realty of ground surface to run a model is more and more highly required. In the real, terrain of the earth surface is always complicated by the natural and human made ground objects. Because of limitation of collecting and storing technologies in the past time, data are usually not detailed so that the data can not be full for the simulation. Besides computing power and simulation increase more day by day, the increasing requirements more detailed of topography surface simulation is a demand. In simulated flooding phenomenon or phenomena related to energy and momentum of water flow, the linear objects of ground surface such as roads, dikes, dams, etc. need to have their vertical dimension along continuously. However, these datas have often no height information alternately, there are only discrete elevation points that are extracted from topographic maps. Consequently, the demand of a suitable method for linear objects height interpolation is necessary. This paper aims to provide a method and evaluate its accuracy to meet this requirement.
基金supported by the National Special Basic Research Fund(Grant No.2008FY110300)National Science and Technology Support Program(Grant No.2011BAC09B07)+1 种基金National Natural Science Foundation of China(Grant No.40961003)Scientific Research Fund Project of Yunnan Education Department(Grant No.2011J018)
文摘Mountains and plateaus in Southwest China contain many subalpine and alpine wetlands, with signifieant hydroecological functions. But ungauged or poorly gauged eonditions limit the study and understanding of hydrological regimes of these wetland types. This study selects an ungauged subalpine wetland - Napahai in Northwest Yunnan, China - as a case for developing a practical approach to revealing its storage-area relationship of open water. A Trimble R8 GNSS （Global Navigation Satellites Systems） RTK （Real-time Kinematic system） and sonar fathometer were used to survey fine- resolution elevation data and generate a digital elevation model of the Napahai Wetland. Forty-four Landsat images from 1987 to 2Oll were collected, and the Normalized Difference Water Index was used to classify open water features in the area. The area of open water in Napahai was ealculated for each phase. With these data and a developed conceptual model, the storage of open water for each phase was estimated using ArcGIS tools. Both storage and area of open water showed significant intra-annual and inter-annual variations. In the rainy season, the monthly change of average storage of open water in Napahai showed about 1-2 months lag behind mean monthly rainfall. The storage-area relationship of open water was well fit by a power function equation （R2=0.91, n=44）. This study indicates that if detailedelevations are available for similarly ungauged subalpine wetlands in Southwest China, researchers can use this practical approach to estimate multi- temporal areas and storages and reveal the storage- area relationship of open water in the wetlands. The study provided valuable information of this ease wetland for optimizing its hydro-ecological managements and a new method to wetland researchers and managers for the hydrological study of similarly ungauged wetland complex.
文摘Groundwater comprises a large portion of irrigation for California＇s agriculture, and sustains a wide diversity of ecosystems as well as consumptive use, but pumping is occurring faster than replenishment. At the same time, contaminants from fertilizers and pesticides are infiltrating into the groundwater, becoming increasingly concentrated as water is extracted. It compared space-based observations of groundwater anomalies from California＇s San Joaquin Valley using the GRACE （gravity recovery and climate experiment） against measurements of 42 organic and inorganic chemicals from 41,667 wells in the valley from 2003 to 2010. It compared Arsenic, Boron, Cadmium, Chloride, Selenium, Trichloroethylene, and TDS （total dissolved solid） concentrations with the groundwater storage anomaly from 2003 to 2010. The results show strong correlations for groundwater depletion against increasing chloride （r2= 0.78, p 〈 0.05） and boron （r2 = 0.88, p 〈 0.05）. This indicates increasing contaminant concentrations while groundwater was depleting over the last eight years. Solubilization by complexation with Cl, CO3 and/or organic chelates may account for the increasing concentration of some heavy metals when groundwater depletion occurs. These results are the first to link space-based groundwater mass change with groundwater contaminant concentration change.
基金the financial supports from the State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining and Technology (No. SKLGDUEK1002)the Fundamental Research Funds for the Central Government Supported Universities of Tongji University, China (No. 0270219037)
文摘Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, among which effectively detecting CO2 from deep underground is one of engineering problems. This paper reviews monitoring techniques currently used during CO2 injection and storage. A method developed based on measuring seismic microtremors is of main interest. This method was first successfully used to characterize a site in this paper. To explore its feasibility in C02 storage monitoring, numerical simulations were conducted to investigate detectable changes in elastic wave signatures due to injection and geological storage of CO2. It is found that, although it is effective for shallow earth profile estimation, the surface wave velocity is not sensitive to the CO2 layer physical parameter variations,especially for a thin CO2 geological storage layer in a deep underground reservoir.
