As a typical region with high water demand for agricultural production,understanding the spatiotemporal surface water changes in Northeast China is critical for water resources management and sustainable development.H...As a typical region with high water demand for agricultural production,understanding the spatiotemporal surface water changes in Northeast China is critical for water resources management and sustainable development.However,the long-term variation characteristics of surface water of different water body types in Northeast China remain rarely explored.This study investigated how surface water bodies of different types(e.g.,lake,reservoir,river,coastal aquaculture,marsh wetland,ephemeral water) changed during1999–2020 in Northeast China based on various remote sensing-based datasets.The results showed that surface water in Northeast China grew dramatically in the past two decades,with an equivalent area increasing from 24 394 km^(2) in 1999 to 34 595 km^(2) in 2020.The surge of ephemeral water is the primary driver of surface water expansion,which could ascribe to shifted precipitation pattern.Marsh wetlands,rivers,and reservoirs experienced a similar trend,with an approximate 20% increase at the interdecadal scale.By contrast,coastal aquacultures and natural lakes remain relatively stable.This study is expected to provide a more comprehensive investigation of the surface water variability in Northeast China and has important practical significance for the scientific management of different types of surface water.展开更多
In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Bas...In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.展开更多
In recent years,remote sensing technology has been widely used to distinguish and extract water body information on the surface of land,investigate and analyze surface water resources,monitor and study ecological envi...In recent years,remote sensing technology has been widely used to distinguish and extract water body information on the surface of land,investigate and analyze surface water resources,monitor and study ecological environment,monitor and assess floods. Remote sensing data provided by MODIS sensor carried on satellites in the United States Earth Observation System（ EOS） have high spatial and temporal resolution and spectral resolution,and images have a wide coverage range and are available for free. Moreover,they can be used for dynamic monitoring of changes in water body area on the earth quickly and efficiently. In this study,based on the analysis of spectral characteristics of water body,the characteristics of MODIS data and the methods of surface water extraction were introduced,and the advantages and disadvantages of various methods of water body extraction were analyzed by the comparison between the practical application effects of these methods.展开更多
Nonlinear wave-body interactions for a stationary surface-piercing body in water of finite depth with fiat and sloping bottoms are simulated in a two-dimensional numerical wave tank, which is constructed mainly based ...Nonlinear wave-body interactions for a stationary surface-piercing body in water of finite depth with fiat and sloping bottoms are simulated in a two-dimensional numerical wave tank, which is constructed mainly based on the spatially averaged Navier-Stokes equations with the k- ε model for simulating the turbulence. The equations are discretized based on the finite volume method and the scheme of the pressure implicit splitting of operators is employed to solve the Navier-Stokes equations. By using the force time histories, the mean and higher-harmonic force components are calculated. The computational results are shown to be in good agreement with experimental and numerical results of other researchers. Then, the horizontal force, the vertical force and the moment on the surface-piercing body under nonlinear regular waves with flat and sloping bottoms are obtained. The results indicate that the bottom topographies have a significant influence on the wave loads on the surface-piercing body.展开更多
基金Under the auspices of Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA28020503,XDA23100102)National Key Research and Development Program of China(No.2019YFA0607101)+1 种基金Project of China Geological Survey(No.DD20230505)Excellent Scientific Research and Innovation Team of Universities in Anhui Province(No.2023AH010071)。
文摘As a typical region with high water demand for agricultural production,understanding the spatiotemporal surface water changes in Northeast China is critical for water resources management and sustainable development.However,the long-term variation characteristics of surface water of different water body types in Northeast China remain rarely explored.This study investigated how surface water bodies of different types(e.g.,lake,reservoir,river,coastal aquaculture,marsh wetland,ephemeral water) changed during1999–2020 in Northeast China based on various remote sensing-based datasets.The results showed that surface water in Northeast China grew dramatically in the past two decades,with an equivalent area increasing from 24 394 km^(2) in 1999 to 34 595 km^(2) in 2020.The surge of ephemeral water is the primary driver of surface water expansion,which could ascribe to shifted precipitation pattern.Marsh wetlands,rivers,and reservoirs experienced a similar trend,with an approximate 20% increase at the interdecadal scale.By contrast,coastal aquacultures and natural lakes remain relatively stable.This study is expected to provide a more comprehensive investigation of the surface water variability in Northeast China and has important practical significance for the scientific management of different types of surface water.
基金Supported by Pennsylvania Service Corporation at Waynesburg, Pennsylvania, USA the 0utstanding Youth Science Foundation of Henan Province （0612002100）, China.
文摘In order to study the effect of Iongwall mining on surface stream water, monitoring stations of water flow rate was established. A lot of water flowing data were collected before, during and after Iongwall mining. Based on monitoring data, the effects of Iongwall mining on surface stream water were analyzed. The results demonstrate that Iongwall mining has effects on the surface stream water; and the stream water would be lost and decrease due to Iongwall mining but never go into underground through fractured zone. Also, the mechanism of water loss due to Iongwall mining was presented. The stream water can go into the surface cracks in the intersection of stream and surface cracks, longwall mining subsidence can change the surface stream slope and the downstream water flowing status. The results also show the effects of Iongwall mining on stream water are temporary and about one or two years later, surface stream water can be recovered.
基金Supported by National Natural Science Foundation of China(41401496)China Postdoctoral Science Foundation(2016M592815)
文摘In recent years,remote sensing technology has been widely used to distinguish and extract water body information on the surface of land,investigate and analyze surface water resources,monitor and study ecological environment,monitor and assess floods. Remote sensing data provided by MODIS sensor carried on satellites in the United States Earth Observation System（ EOS） have high spatial and temporal resolution and spectral resolution,and images have a wide coverage range and are available for free. Moreover,they can be used for dynamic monitoring of changes in water body area on the earth quickly and efficiently. In this study,based on the analysis of spectral characteristics of water body,the characteristics of MODIS data and the methods of surface water extraction were introduced,and the advantages and disadvantages of various methods of water body extraction were analyzed by the comparison between the practical application effects of these methods.
基金Project supported by the National Natural Science Foundation of China (Grant No. 40776057)the Knowledge Innovation Program of Chinese Academy of Sciences (Grant Nos. KJCX2-YW-L07,KZCX2-YW-212-2)
文摘Nonlinear wave-body interactions for a stationary surface-piercing body in water of finite depth with fiat and sloping bottoms are simulated in a two-dimensional numerical wave tank, which is constructed mainly based on the spatially averaged Navier-Stokes equations with the k- ε model for simulating the turbulence. The equations are discretized based on the finite volume method and the scheme of the pressure implicit splitting of operators is employed to solve the Navier-Stokes equations. By using the force time histories, the mean and higher-harmonic force components are calculated. The computational results are shown to be in good agreement with experimental and numerical results of other researchers. Then, the horizontal force, the vertical force and the moment on the surface-piercing body under nonlinear regular waves with flat and sloping bottoms are obtained. The results indicate that the bottom topographies have a significant influence on the wave loads on the surface-piercing body.
文摘在国家复苏河湖生态环境的要求下,分析京津冀平原区长序列水面面积变化特征及变化原因,有助于科学制定区域生态补水量及预测补水效果。研究通过3期土地利用数据融合确定了京津冀平原区的水域面积,基于GEE(Google Earth Engine)云平台提取了1985—2020年京津冀平原区长序列水面面积,并分析了水域面积填充率及水面面积演变原因。结果表明,京津冀平原区水面面积呈增加趋势,与1985年相比,2020年中部平原区水域面积填充率由3.6%增加到18.5%,滨海平原区水域面积填充率由30%增加到45%;生态补水是河湖水面面积增加的主要原因,2020年较2001年中部平原区水面面积增加了176 km 2,本地和南水北调生态补水的贡献占到84%。进一步以河湖复苏为目标,从水域面积填充率的角度设置了不同情景,分别估算了不同情景下的河湖生态需水量,为未来生态补水计划提供参考。研究成果系统分析了京津冀平原区水面现状及生态补水的效果,对京津冀平原区开展合理河湖复苏措施具有重要意义。
