Automated image classification and visual interpretation of Landsat imagery were used to extract the glacier boundary in the Nujiang-Salween River Basin(NSRB)around the years 1975,2000,and 2020.The spatiotemporal char...Automated image classification and visual interpretation of Landsat imagery were used to extract the glacier boundary in the Nujiang-Salween River Basin(NSRB)around the years 1975,2000,and 2020.The spatiotemporal characteristics of glacier area changes in the NSRB were determined and the reasons for the spatial heterogeneity in glacier area changes were discussed,based on comparative analyses of temperature and precipitation data from meteorological stations around the NSRB.The results indicate that 1)the total glacier area in the NSRB decreased by 477.78 km^(2)(28.17%)at a rate of-0.62%/a in 1975-2020.Most shrinkage occurred at low and mid altitudes,with the most severe occurring at 5290-5540 m,accounting for 40%of the total shrinkage.Considering other river basins in China,the relative glacier area change rate in the NSRB was similar to that for typical inland river basins in northwest China but lower than that for other transboundary river basins in the southeastern Tibetan Plateau.2)These areal changes in the NSRB presented obvious regional differences.The glaciers in the Hengduan Mountains retreated significantly,followed by those in the Nyainqentanglha Mountains,with relatively low shrinkage observed in the Tanggula Mountains.The number of cold and hot spots indicating areal changes increased after 2000,along with their spatial heterogeneity.3)The glacier shrinkage rate over different time intervals was positively correlated with temperature.Thus,spatial heterogeneity of climate change effects could elucidate differences in the glacier area change rate in different regions of the NSRB.The temperature rise was determined as the primary reason for the significant glacial retreat over the past 45 years.As the significant warming trend continues,the glacier area in the NSRB is likely to shrink further.展开更多
The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by a...The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by approximately 6.7 million people.The basin has limited hydraulic conservancy infrastructure and insufficient ability to cope with climate change risks.Studying the hydrological characteristics and changes in the basin provides the scientific basis for rational protection and development of the basin.However,owing to the limitation of observation data,previous studies have focused on the local area and neglected the study of the lower reaches,which is not enough to reflect the spatial characteristics of the entire basin.In this study,the ECMWF 5th generation reanalysis data(ERA5)and Multi-Source Weighted-Ensemble Precipitation(MSWEP)were applied to develop a geomorphology-based hydrological model(GBHM)for reconstructing hydrological datasets(i.e.GBHM-ERA5 and GBHM-MSWEP).The reconstructed datasets covering the complete basin were verified against the gauge observation and compared with other commonly used streamflow products,including Global Flood Awareness System v2.1,GloFAS-Reanalysis dataset v3.0,and linear optimal runoff aggregate(LORA).The comparison results revealed that GBHM-ERA5 is significantly better than the other four datasets and provides a good reproduction of the hydrological characteristics and trends of the NSR.Detailed analysis of GBHM-ERA5 revealed that:(1)A multi-year mean surface runoff represented 39%of precipitation over the basin during 1980–2018,which had low surface runoff in the upstream,while areas around the Three Parallel Rivers Area and the estuary had abundant surface runoff.(2)The surface runoff and discharge coefficient of variations in spring were larger than those in other seasons,and the inter-annual variation in the downstream was smaller than that in the upstream and midstream regions.(3)More than 70%of the basin areas showed a decreasing trend in the surface ru展开更多
基金National Natural Science Foundation of China,No.42061005,No.41561003Science and Technology Projects of Yunnan Province,No.202101AT070110。
文摘Automated image classification and visual interpretation of Landsat imagery were used to extract the glacier boundary in the Nujiang-Salween River Basin(NSRB)around the years 1975,2000,and 2020.The spatiotemporal characteristics of glacier area changes in the NSRB were determined and the reasons for the spatial heterogeneity in glacier area changes were discussed,based on comparative analyses of temperature and precipitation data from meteorological stations around the NSRB.The results indicate that 1)the total glacier area in the NSRB decreased by 477.78 km^(2)(28.17%)at a rate of-0.62%/a in 1975-2020.Most shrinkage occurred at low and mid altitudes,with the most severe occurring at 5290-5540 m,accounting for 40%of the total shrinkage.Considering other river basins in China,the relative glacier area change rate in the NSRB was similar to that for typical inland river basins in northwest China but lower than that for other transboundary river basins in the southeastern Tibetan Plateau.2)These areal changes in the NSRB presented obvious regional differences.The glaciers in the Hengduan Mountains retreated significantly,followed by those in the Nyainqentanglha Mountains,with relatively low shrinkage observed in the Tanggula Mountains.The number of cold and hot spots indicating areal changes increased after 2000,along with their spatial heterogeneity.3)The glacier shrinkage rate over different time intervals was positively correlated with temperature.Thus,spatial heterogeneity of climate change effects could elucidate differences in the glacier area change rate in different regions of the NSRB.The temperature rise was determined as the primary reason for the significant glacial retreat over the past 45 years.As the significant warming trend continues,the glacier area in the NSRB is likely to shrink further.
基金This work is jointly supported by the National Key Research and Development Program of China(2016YFA0601603)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0206)+1 种基金the National Natural Science Foundation of China(91747101&41801260)the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20100103).
文摘The Nu-Salween River(NSR),the longest free-flow river in Southeast Asia,plays an irreplaceable role in social development and ecological protection.The lower NSR region is particularly valuable as it is inhabited by approximately 6.7 million people.The basin has limited hydraulic conservancy infrastructure and insufficient ability to cope with climate change risks.Studying the hydrological characteristics and changes in the basin provides the scientific basis for rational protection and development of the basin.However,owing to the limitation of observation data,previous studies have focused on the local area and neglected the study of the lower reaches,which is not enough to reflect the spatial characteristics of the entire basin.In this study,the ECMWF 5th generation reanalysis data(ERA5)and Multi-Source Weighted-Ensemble Precipitation(MSWEP)were applied to develop a geomorphology-based hydrological model(GBHM)for reconstructing hydrological datasets(i.e.GBHM-ERA5 and GBHM-MSWEP).The reconstructed datasets covering the complete basin were verified against the gauge observation and compared with other commonly used streamflow products,including Global Flood Awareness System v2.1,GloFAS-Reanalysis dataset v3.0,and linear optimal runoff aggregate(LORA).The comparison results revealed that GBHM-ERA5 is significantly better than the other four datasets and provides a good reproduction of the hydrological characteristics and trends of the NSR.Detailed analysis of GBHM-ERA5 revealed that:(1)A multi-year mean surface runoff represented 39%of precipitation over the basin during 1980–2018,which had low surface runoff in the upstream,while areas around the Three Parallel Rivers Area and the estuary had abundant surface runoff.(2)The surface runoff and discharge coefficient of variations in spring were larger than those in other seasons,and the inter-annual variation in the downstream was smaller than that in the upstream and midstream regions.(3)More than 70%of the basin areas showed a decreasing trend in the surface ru
