Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. For centuries, people inhabiting the Dongting Lake area have been reclaiming land and constructing dams for flood resistance, agri...Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. For centuries, people inhabiting the Dongting Lake area have been reclaiming land and constructing dams for flood resistance, agricultural production, and rural settlement, forming geographical entities known as polders. In this study, the regional spatial distributions of polders in the Dongting Lake area in 1949, 1998, and 2013 were obtained using historical maps and modern remotely sensed data, revealing changes since the establishment of the People's Republic of China. Nanxian County was then selected to demonstrate polder changes at the county level, because it has undergone the most dramatic changes in the area. Different polder change models for the Datonghu, Yule, and Renhe polders were analyzed for eight periods: 1644(the early Qing Dynasty), 1911(the late Qing Dynasty), 1930(the Republic of China), 1949(the People's Republic of China), 1963, 1970, 1998, and 2013. Three resulting polder evolution models are: 1) reclaiming polders from lakes, 2) integrating polders by stream merging, and 3) abandoning polders for flood release. The polder evolution models demonstrate the wisdom of local people in using land resources according to the specific regional conditions. Throughout their long-term historical evolution, the spatial distribution of polders in the Dongting Lake area tended to be homogeneous, and the degree of human disturbance tended to be stable. However, a shift occurred, from pure polder area growth or removal to more comprehensive management and protection of the regional environment.展开更多
由法国空间研究中心(CNES)于2004年12月18日发射的PARA SOL(Po larization&A n isotropy of R eflectances for A tm ospheric Sciences coup led w ith Observations from a L idar)卫星,是法国和美国合作的“卫星列车”(“A-T rai...由法国空间研究中心(CNES)于2004年12月18日发射的PARA SOL(Po larization&A n isotropy of R eflectances for A tm ospheric Sciences coup led w ith Observations from a L idar)卫星,是法国和美国合作的“卫星列车”(“A-T rain”)计划中的一员,上面主要搭载了POLDER(Po larization and D irectionality of the E arth's R eflectances)仪器,可以通过全球观测,从空间收集地气系统反射太阳辐射的偏振性和方向性数据。从这些数据,我们可以获得地表、大气气溶胶及云的多种特性,这些信息是改进气候数值模式所必需的。主要以POLDER仪器为例,就多光谱、多角度和多偏振联合遥感观测地气系统方面的进展进行综述。展开更多
Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the E...Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the Earth＇s Reflectances）/PARASOL （Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar） multi-directional, multi-spectral polarized signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET （AErosol RObotic NETwork）/PHOTONS （PHOtometrie pour le Traitement Operational de Normalisation Satellitaire） measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness （AOT） and effective radius are 0.06 and 0.05 μm respectively, which are close to or better than the required accuracies （0.04 for AOT and 0.1 μm for effective radius） for estimating aerosol direct forcing.展开更多
The heavy floods in the Taihu Basin showed increasing trend in recent years. In this work, a typical area in the northern Taihu Basin was selected for flood risk analysis and potential flood losses assessment. Human a...The heavy floods in the Taihu Basin showed increasing trend in recent years. In this work, a typical area in the northern Taihu Basin was selected for flood risk analysis and potential flood losses assessment. Human activities have strong impact on the study area’s flood situation (as affected by the polders built, deforestation, population increase, urbanization, etc.), and have made water level higher, flood duration shorter, and flood peaks sharper. Five years of different flood return periods [(1970), 5 (1962), 10 (1987), 20 (1954), 50 (1991)] were used to calculate the potential flood risk area and its losses. The potential flood risk map, economic losses, and flood-impacted population were also calculated. The study’s main conclusions are: 1) Human activities have strongly changed the natural flood situation in the study area, increasing runoff and flooding; 2) The flood risk area is closely related with the precipitation center; 3) Polder construction has successfully protected land from flood, shortened the flood duration, and elevated water level in rivers outside the polders; 4) Economic and social development have caused flood losses to increase in recent years.展开更多
Polder is a type of irrigation field unique to the lower Yangtze River of China.It is a product of long-term and ingenuous human modifications of wetland landscapes.In the pre-Qin Period,3000 years ago,the poldered ar...Polder is a type of irrigation field unique to the lower Yangtze River of China.It is a product of long-term and ingenuous human modifications of wetland landscapes.In the pre-Qin Period,3000 years ago,the poldered area of eastern Wuhu city was once a large lake called the ancient Danyang wetland.The introduction of agricultural civilization and polder technology to the area during the Wu and Yue Kingdoms period gradually transformed it into an agricultural area.With an accelerating rate of land reclamation under a changing late-Holocene regional climate,the ancient Danyang wetland became an aquatic system strongly influenced by intensifying anthropogenic activities.In this study,based on field survey data,historical documents,and remote-sensing and archaeological data,we reconstructed the spatial distribution of the polder landscape over the last 3000 years and identified their structural diversity.We found that polder landscapes began to emerge in the Spring and Autumn Period,land reclamation intensified in the Three Kingdoms and developed rapidly in the Song Dynasty before eventually reaching the peak from the Ming and Qing Dynasties.The relocation of historical sites to low-altitude areas also marked the expansion of poldered fields from the center of the wetland to the southeast and northwest.The development and evolution of the polder landscape are related to regional climate conditions,changing social and economic statuses,and the development of agricultural technology in the Song Dynasty and succeeding periods.展开更多
The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human developme...The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human development and livelihoods of communities in the Dongting Lake area. This paper is prepared for analysing the best practices in wise-use and sustainable management of wetland and their socioeconomic benefits in Polder Xipanshanzhou in Dongting Lake. The quantitative （monetary values） and qualitative socioeconomic data of 1683 samples from questionnaire surveys during 2000 to 2008 were used for this study, of which 1173 were obtained in Polder Xipanshanzhou. Five conclusions are drawn from the study： （i） the community-based alternative activities and wise-use in Polder Xipanshanzhou after ＂Returning Farmland to Lake＂ （RFL） resulted in more income, increased well-being, reduced vulnerability to food shortage, poverty and flooding, and more sustainable use of the natural resource base; （ii） women, elder farmers, and low-income groups benefited much more from these activities; （iii） livelihood continued to improve as compared with that when the project started in 2000, and project participating households earned more income and owned more properties than non-project households. Even after the external funding stopped in 2001, its positive accumulated effects have still been significantly contributing to the improvement of livelihoods of this community; （iv） social structures within Polder Xipanshanzhou have been evolving in a positive way, community-based grass-roots organizations have emerged and developed well, and the capacities of community-based participatory co-management, self-governing and self- development, as well as local awareness of environmental issues have been improving, which attract more local people to be interested in such wise-use activities; and （v） the success can be attributed to the mobilization of local communities, favorable national policies, Public-Private Partnership （PPP）, institutional arrangements in local communities, and adaptive management and innovative approaches.展开更多
目前,偏振遥感已被用于气溶胶卫星和地基遥感中,其仅对小粒子敏感。本研究以2007-2008年间的POLDER(Polarization and Directionality of the Earth’s Reflectances)和AERONET(Aerosol Robotic Network)合肥站的气溶胶数据为研究对象,...目前,偏振遥感已被用于气溶胶卫星和地基遥感中,其仅对小粒子敏感。本研究以2007-2008年间的POLDER(Polarization and Directionality of the Earth’s Reflectances)和AERONET(Aerosol Robotic Network)合肥站的气溶胶数据为研究对象,探讨了偏振遥感对气溶胶粒子尺度的敏感性。利用AERONET合肥站的尺度分布数据和折射指数数据,计算了不同尺度范围内气溶胶粒子的光学厚度,并与对应的POLDER反演结果作拟合,通过寻找最佳拟合对应的尺度范围确定偏振遥感敏感的粒子尺度。结果表明,偏振遥感并非对所有尺度的小模式气溶胶粒子都敏感,在865 nm波段,其敏感的气溶胶粒子上限半径约为0.3μm左右。这一结果对指导气溶胶偏振遥感,以及理解和应用偏振遥感气溶胶产品等具有重要意义。展开更多
在卫星海洋遥感中,云作为海气耦合系统最重要的调节器之一,其检测结果对海洋上空云微物理特性的反演精度有较大影响。因此,快速而准确识别海洋上空的云像元是卫星遥感数据处理过程中首要解决的关键问题。以PARASOL (Polarization and An...在卫星海洋遥感中,云作为海气耦合系统最重要的调节器之一,其检测结果对海洋上空云微物理特性的反演精度有较大影响。因此,快速而准确识别海洋上空的云像元是卫星遥感数据处理过程中首要解决的关键问题。以PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar)卫星搭载的POLDER3载荷遥感数据为研究对象,提出一种改进的海洋上空云检测方法。首先剔除海洋耀光;接着利用有云与晴空区近红外反射率差异检验识别有云像元,并利用偏振反射率检验进一步识别低反射率的云像元;然后利用近红外与可见光反射率比值检验识别晴空像元;最后建立多角度云检测结果空间融合规则,重新标记有云、晴空和未定像元。以印度洋海区为例进行实验分析,将云检测结果与Buriez方法进行对比,发现检测精度基本相当,而有云像元的识别速度却平均提高约3倍。结果表明:该方法能有效的检测出海洋上空的云像元,满足业务化数据处理的高精度及时效性要求,为后续云微物理特性反演提供可靠的数据源。展开更多
基金Science & Technology Basic Research Program of China,No.2011FY110400,No.2013FY114600National Natural Science Foundation of China,No.41301474+1 种基金China Postdoctoral Science Foundation,No.2014T70114Disaster Risk Reduction Knowledge Service of IKCEST,CKCEST-2016-3-7
文摘Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. For centuries, people inhabiting the Dongting Lake area have been reclaiming land and constructing dams for flood resistance, agricultural production, and rural settlement, forming geographical entities known as polders. In this study, the regional spatial distributions of polders in the Dongting Lake area in 1949, 1998, and 2013 were obtained using historical maps and modern remotely sensed data, revealing changes since the establishment of the People's Republic of China. Nanxian County was then selected to demonstrate polder changes at the county level, because it has undergone the most dramatic changes in the area. Different polder change models for the Datonghu, Yule, and Renhe polders were analyzed for eight periods: 1644(the early Qing Dynasty), 1911(the late Qing Dynasty), 1930(the Republic of China), 1949(the People's Republic of China), 1963, 1970, 1998, and 2013. Three resulting polder evolution models are: 1) reclaiming polders from lakes, 2) integrating polders by stream merging, and 3) abandoning polders for flood release. The polder evolution models demonstrate the wisdom of local people in using land resources according to the specific regional conditions. Throughout their long-term historical evolution, the spatial distribution of polders in the Dongting Lake area tended to be homogeneous, and the degree of human disturbance tended to be stable. However, a shift occurred, from pure polder area growth or removal to more comprehensive management and protection of the regional environment.
基金973 Program of China under Grant No.2006CB403702National Science Foundation of China(40805010)the French-Chinese Programme de Recherches Avancées(PRAE04-02)
文摘由法国空间研究中心(CNES)于2004年12月18日发射的PARA SOL(Po larization&A n isotropy of R eflectances for A tm ospheric Sciences coup led w ith Observations from a L idar)卫星,是法国和美国合作的“卫星列车”(“A-T rain”)计划中的一员,上面主要搭载了POLDER(Po larization and D irectionality of the E arth's R eflectances)仪器,可以通过全球观测,从空间收集地气系统反射太阳辐射的偏振性和方向性数据。从这些数据,我们可以获得地表、大气气溶胶及云的多种特性,这些信息是改进气候数值模式所必需的。主要以POLDER仪器为例,就多光谱、多角度和多偏振联合遥感观测地气系统方面的进展进行综述。
基金supported by National Natural Science Foundation of China(Grant No.40805010)the 973 Program of China under Grant No.2006CB403702
文摘Aerosol optical properties over Beijing and Xianghe under several typical weather conditions （clear sky, light haze, heavy pollution and dust storm） are derived from POLDER （POLarization and Directionality of the Earth＇s Reflectances）/PARASOL （Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar） multi-directional, multi-spectral polarized signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET （AErosol RObotic NETwork）/PHOTONS （PHOtometrie pour le Traitement Operational de Normalisation Satellitaire） measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness （AOT） and effective radius are 0.06 and 0.05 μm respectively, which are close to or better than the required accuracies （0.04 for AOT and 0.1 μm for effective radius） for estimating aerosol direct forcing.
文摘The heavy floods in the Taihu Basin showed increasing trend in recent years. In this work, a typical area in the northern Taihu Basin was selected for flood risk analysis and potential flood losses assessment. Human activities have strong impact on the study area’s flood situation (as affected by the polders built, deforestation, population increase, urbanization, etc.), and have made water level higher, flood duration shorter, and flood peaks sharper. Five years of different flood return periods [(1970), 5 (1962), 10 (1987), 20 (1954), 50 (1991)] were used to calculate the potential flood risk area and its losses. The potential flood risk map, economic losses, and flood-impacted population were also calculated. The study’s main conclusions are: 1) Human activities have strongly changed the natural flood situation in the study area, increasing runoff and flooding; 2) The flood risk area is closely related with the precipitation center; 3) Polder construction has successfully protected land from flood, shortened the flood duration, and elevated water level in rivers outside the polders; 4) Economic and social development have caused flood losses to increase in recent years.
基金National Natural Science Foundation of China,No.42271173,No.41771221Key Project of the 14th Five-Year Plan of Anhui,No.2022BFAFZ01365National Key Program of Innovation Training for College Students,No.202310370039,No.202310370049,No.S202310370332。
文摘Polder is a type of irrigation field unique to the lower Yangtze River of China.It is a product of long-term and ingenuous human modifications of wetland landscapes.In the pre-Qin Period,3000 years ago,the poldered area of eastern Wuhu city was once a large lake called the ancient Danyang wetland.The introduction of agricultural civilization and polder technology to the area during the Wu and Yue Kingdoms period gradually transformed it into an agricultural area.With an accelerating rate of land reclamation under a changing late-Holocene regional climate,the ancient Danyang wetland became an aquatic system strongly influenced by intensifying anthropogenic activities.In this study,based on field survey data,historical documents,and remote-sensing and archaeological data,we reconstructed the spatial distribution of the polder landscape over the last 3000 years and identified their structural diversity.We found that polder landscapes began to emerge in the Spring and Autumn Period,land reclamation intensified in the Three Kingdoms and developed rapidly in the Song Dynasty before eventually reaching the peak from the Ming and Qing Dynasties.The relocation of historical sites to low-altitude areas also marked the expansion of poldered fields from the center of the wetland to the southeast and northwest.The development and evolution of the polder landscape are related to regional climate conditions,changing social and economic statuses,and the development of agricultural technology in the Song Dynasty and succeeding periods.
基金National Natural Science Foundation of China (grant number: 30670374)National Basic Research Program of China (973 Program): Ecosystem Services and Ecological Safety of the Major Terrestrial Ecosystems of China (grant number: 2009CB421106)WWF (World Wide Fund for Nature) International Collaboration Program: Wetland Ecosystem Assessment and Management in Dongting Lake (grant number: CN0088.03-YB01/02/03/04)
文摘The frequent occurrence of extreme flood events in the late 1990s and the past decade has brought about an ongoing debate on the relationships between wetland resources, wetland ecosystem services, and human development and livelihoods of communities in the Dongting Lake area. This paper is prepared for analysing the best practices in wise-use and sustainable management of wetland and their socioeconomic benefits in Polder Xipanshanzhou in Dongting Lake. The quantitative （monetary values） and qualitative socioeconomic data of 1683 samples from questionnaire surveys during 2000 to 2008 were used for this study, of which 1173 were obtained in Polder Xipanshanzhou. Five conclusions are drawn from the study： （i） the community-based alternative activities and wise-use in Polder Xipanshanzhou after ＂Returning Farmland to Lake＂ （RFL） resulted in more income, increased well-being, reduced vulnerability to food shortage, poverty and flooding, and more sustainable use of the natural resource base; （ii） women, elder farmers, and low-income groups benefited much more from these activities; （iii） livelihood continued to improve as compared with that when the project started in 2000, and project participating households earned more income and owned more properties than non-project households. Even after the external funding stopped in 2001, its positive accumulated effects have still been significantly contributing to the improvement of livelihoods of this community; （iv） social structures within Polder Xipanshanzhou have been evolving in a positive way, community-based grass-roots organizations have emerged and developed well, and the capacities of community-based participatory co-management, self-governing and self- development, as well as local awareness of environmental issues have been improving, which attract more local people to be interested in such wise-use activities; and （v） the success can be attributed to the mobilization of local communities, favorable national policies, Public-Private Partnership （PPP）, institutional arrangements in local communities, and adaptive management and innovative approaches.
文摘目前,偏振遥感已被用于气溶胶卫星和地基遥感中,其仅对小粒子敏感。本研究以2007-2008年间的POLDER(Polarization and Directionality of the Earth’s Reflectances)和AERONET(Aerosol Robotic Network)合肥站的气溶胶数据为研究对象,探讨了偏振遥感对气溶胶粒子尺度的敏感性。利用AERONET合肥站的尺度分布数据和折射指数数据,计算了不同尺度范围内气溶胶粒子的光学厚度,并与对应的POLDER反演结果作拟合,通过寻找最佳拟合对应的尺度范围确定偏振遥感敏感的粒子尺度。结果表明,偏振遥感并非对所有尺度的小模式气溶胶粒子都敏感,在865 nm波段,其敏感的气溶胶粒子上限半径约为0.3μm左右。这一结果对指导气溶胶偏振遥感,以及理解和应用偏振遥感气溶胶产品等具有重要意义。
文摘在卫星海洋遥感中,云作为海气耦合系统最重要的调节器之一,其检测结果对海洋上空云微物理特性的反演精度有较大影响。因此,快速而准确识别海洋上空的云像元是卫星遥感数据处理过程中首要解决的关键问题。以PARASOL (Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar)卫星搭载的POLDER3载荷遥感数据为研究对象,提出一种改进的海洋上空云检测方法。首先剔除海洋耀光;接着利用有云与晴空区近红外反射率差异检验识别有云像元,并利用偏振反射率检验进一步识别低反射率的云像元;然后利用近红外与可见光反射率比值检验识别晴空像元;最后建立多角度云检测结果空间融合规则,重新标记有云、晴空和未定像元。以印度洋海区为例进行实验分析,将云检测结果与Buriez方法进行对比,发现检测精度基本相当,而有云像元的识别速度却平均提高约3倍。结果表明:该方法能有效的检测出海洋上空的云像元,满足业务化数据处理的高精度及时效性要求,为后续云微物理特性反演提供可靠的数据源。
