Response of the runoff in the headwater region of the Yellow River to climate change and its sensibility are analyzed based on the measured data at the four hydrological stations and ten weather stations during the pe...Response of the runoff in the headwater region of the Yellow River to climate change and its sensibility are analyzed based on the measured data at the four hydrological stations and ten weather stations during the period 1959-2008. The result indicates that change of temperature in the region has an obvious corresponding relationship with global warming and the changes of annual average temperature in each subregion in the region have been presenting a fluctuant and rising state in the past 50 years. However the change of precipitation is more intricate than the change of temperature in the region because of the influences of the different geographical positions and environments in various areas, and the change of annual precipitation in the main runoff-producing area has been presenting a fluctuant and decreasing state in the past 50 years. And there is a remarkable nonlinear correlativity between runoff and precipitation and temperature in the region. The runoff in the region has been decreasing continuously since 1990 because the precipitation in the main run-off-producing area obviously decreases and the annual average temperature continuously rises. As a whole, the runoff in each subregion of the headwater region of the Yellow River is quite sensitive to precipitation change, while the runoff in the subregion above Jimai is more sensitive to temperature change than that in the others in the region, correspondingly.展开更多
To understand the variations in surface water associated with changes in air temperature,precipitation,and permafrost in the Headwater Area of the Yellow River(HAYR),we studied the dynamics of alpine lakes larger than...To understand the variations in surface water associated with changes in air temperature,precipitation,and permafrost in the Headwater Area of the Yellow River(HAYR),we studied the dynamics of alpine lakes larger than 0.01 km^2 during 1986-2019 using Google Earth Engine(GEE)platform.The surface areas of water bodies in the HAYR were processed using mass remote sensing images consisting of Landsat TM/ETM-H/OLI,Sentinel-2A,and MODIS based on automatic extraction of water indices under GEE.Besides,the lake ice phenology of the Sister Lakes(the Gyaring Lake and the Ngoring Lake)was derived by threshold segmenting of water/ice area ratio.Results demonstrate that the change of surface areas experienced four stages:decreasing during 1986-2004,increasing during 2004-2012,decreasing again during 2012-2017,and increasing again during 2017-2019.Correspondingly,the number of small lakes decreased(-26.5 per year),increased(139.5 per year),again decreased(-109.0 per year),and again increased(433.0 per year).Eight lakes larger than 1 km^2 disappeared in 2004 but restored afterward.The overall trends in the area of small lakes(0.01-1 km^2),large lakes(>1 km^2),and all lakes during 1986-2019 were 0.4,3.1,and 3.4 km^2 per year,respectively.Although the onsets of freezing,freeze-up,breaking and the break-up of the Sister Lakes varied from year to year,there is no obvious trend regarding the lake ice phenology.Tendencies of lake variations in the HAYR are primarily related to the increased net precipitation and the declined aridity,followed by the construction of hydropower station around the outlet of the Ngoring Lake,as well as permafrost degradation.展开更多
基金Knowledge Innovation Program of the Chinese Academy of Sciences, No.KZCX2-YW-328 No.J0930003/J0109 Key Program of National Natural Science Foundation of China, No.907020011 No.INFO- 115-C01-SDB2-03+1 种基金 National Natural Science Foundation of China, No.40777047 No.40675066
文摘Response of the runoff in the headwater region of the Yellow River to climate change and its sensibility are analyzed based on the measured data at the four hydrological stations and ten weather stations during the period 1959-2008. The result indicates that change of temperature in the region has an obvious corresponding relationship with global warming and the changes of annual average temperature in each subregion in the region have been presenting a fluctuant and rising state in the past 50 years. However the change of precipitation is more intricate than the change of temperature in the region because of the influences of the different geographical positions and environments in various areas, and the change of annual precipitation in the main runoff-producing area has been presenting a fluctuant and decreasing state in the past 50 years. And there is a remarkable nonlinear correlativity between runoff and precipitation and temperature in the region. The runoff in the region has been decreasing continuously since 1990 because the precipitation in the main run-off-producing area obviously decreases and the annual average temperature continuously rises. As a whole, the runoff in each subregion of the headwater region of the Yellow River is quite sensitive to precipitation change, while the runoff in the subregion above Jimai is more sensitive to temperature change than that in the others in the region, correspondingly.
基金National Key Research and Development Program of China(2017YFC0405701)the National Natural Science Foundation(NSF)of China(41671060).
文摘To understand the variations in surface water associated with changes in air temperature,precipitation,and permafrost in the Headwater Area of the Yellow River(HAYR),we studied the dynamics of alpine lakes larger than 0.01 km^2 during 1986-2019 using Google Earth Engine(GEE)platform.The surface areas of water bodies in the HAYR were processed using mass remote sensing images consisting of Landsat TM/ETM-H/OLI,Sentinel-2A,and MODIS based on automatic extraction of water indices under GEE.Besides,the lake ice phenology of the Sister Lakes(the Gyaring Lake and the Ngoring Lake)was derived by threshold segmenting of water/ice area ratio.Results demonstrate that the change of surface areas experienced four stages:decreasing during 1986-2004,increasing during 2004-2012,decreasing again during 2012-2017,and increasing again during 2017-2019.Correspondingly,the number of small lakes decreased(-26.5 per year),increased(139.5 per year),again decreased(-109.0 per year),and again increased(433.0 per year).Eight lakes larger than 1 km^2 disappeared in 2004 but restored afterward.The overall trends in the area of small lakes(0.01-1 km^2),large lakes(>1 km^2),and all lakes during 1986-2019 were 0.4,3.1,and 3.4 km^2 per year,respectively.Although the onsets of freezing,freeze-up,breaking and the break-up of the Sister Lakes varied from year to year,there is no obvious trend regarding the lake ice phenology.Tendencies of lake variations in the HAYR are primarily related to the increased net precipitation and the declined aridity,followed by the construction of hydropower station around the outlet of the Ngoring Lake,as well as permafrost degradation.