AerialphototakenonApril21,2022showsrangerspatrolingaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xinhua/ZhangLong)

RangerspatrolaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince,April21,2022.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xinhua/ZhangLong)

ArangerfixesthefencesaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince,April21,2022.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xinhua/ZhangLong)

ArangerpatrolsaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince,April21,2022.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xinhua/ZhangLong)

AerialphototakenonApril21,2022showsarangerpatrolingaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xinhua/ZhangLong)

RangerspatrolaroundYoigilanglebQu(river)inQumalaiCountyofYushuTibetanAutonomousPrefectureinnorthwestChina'sQinghaiProvince,April21,2022.YoigilanglebQu(river)islocatedatthecoreareaofSanjiangyuanNationalPark.Sanjiangyuan,meaningthe"sourceofthreerivers,"ishometotheheadwatersoftheYangtze,YellowandLancangrivers.(Xi