| Due to the steep terrain,high altitude and sparse population of the Tibetan Plateau,the lake is less affected by human activities and is almost in a natural state.Therefore,the changes of the lake are only affected by the surrounding natural conditions,that is,the changes of the lake can reflect to some extent Regional climate change status.Compared with the limitations of traditional methods for observing lakes,remote sensing technology has obvious advantages in areas with harsh natural environment and lack of ground observation because of its timeliness,periodicity and wide observation range.In the past few decades,with the redistribution of water,great changes have taken place in many glacier and lake regions,and the research on the changes of water resources in the Tibetan Plateau has gradually become one of the hot spots.Most of these researches focus on the temporal and spatial changes of climate in the entire region of the Tibetan Plateau or typical watersheds.In order to better understand the distribution pattern of water resources and the dynamic changes of lakes on the watershed scale,it is of great significance to study the changes of lakes on the Tibetan Plateau according to different types of watershed recharge.Based on Hydro SHEDS hydrological data,The Randolph Glacier Inventory 6.0 global glacier inventory data and river vector data in the Tibetan Plateau region,this paper reclassifies the Tibetan Plateau watershed into four categories,namely,glacier-stream watershed,glacier-stream-free watershed,glacier-stream-free watershed and glacier-stream-free watershed,and then starts with watershed scale.Through collecting and sorting out a large number of scholars'research data on lakes in the Tibetan Plateau in recent years,the changes of lakes in the Tibetan Plateau are analyzed as the basic data of lakes,so as to comprehensively analyze the changes of lakes in different river basins in the Tibetan Plateau and their spatio-temporal changes and causes.The main conclusions of the paper are as follows:(1)The area of 65 typical lakes in the Tibetan Plateau is analyzed.Based on the temporal heterogeneity,the change of lake area in the Tibetan Plateau can be divided into five types and eight subtypes.Most lakes in the Tibetan Plateau are in an increasing trend,while only a few lakes are in a decreasing trend.The decrease in Zigui fault is the most obvious,with a decrease of-10.23km~2/a,and the total area decreased 317.19km~2 from 1970 to 2010.The area of silvan fault increased most obviously,with a trend of 15.1km~2/a,and the total area increased 646.88km~2 from 1970 to 2010.(2)The water level of 46 typical lakes in the Tibetan Plateau is analyzed.Based on the temporal heterogeneity,the water level changes of lakes in the Tibetan Plateau can be divided into three types and four subtypes.The water level of most lakes in the Tibetan Plateau is on an upward trend,while only a few lakes are on a downward trend.Among them,Kusai Lake has the fastest rising rate,rising at a trend of 0.9m/a,with a total water level rising by 9.56m from 2000 to 2018.The falling rate of consternation water level is the fastest,with a trend of 0.99m/a,but the overall water level changes little.Secondly,the water level in Zhuonaihu Tibetan Antelope Aggregation dropped by 11.64m from 2000 to 2018 at a rate of0.84 m/a.(3)Analyzing the water volume of 55 typical lakes on the Tibetan Plateau,most lakes are expanding rapidly.For example,Selinsico increased at a rate of 1.22Gt/yr during the study period,while Kusai Lake suddenly expanded due to floods,obtaining 5.05Gt of water in 2011and increasing at a rate of 0.31Gt/yr during the study period.On the other hand,the Zhuonaihu Tibetan Antelope Aggregation in the upper reaches of Lake Cuse changed in the opposite direction.Among the 55 lakes studied,the shrinkage was the most obvious and decreased at a rate of-0.2Gt/yr during the study period.There are only 9 shrinking lakes,accounting for 16%of the total number of lakes studied.(4)Analysis of the lake area,area,and water volume of different types of watersheds.The lake area,water level,and water volume of various types of watersheds change basically the same.As the area increases,the water level and water volume also rise.For the lake area changes in different watersheds,the area change rate of the non-glacier and stream basins in the four periods from 1970 to 2010 was higher than that of the glacier and non-brook watersheds and the glaciers and the stream stream basins,indicating that the impact of streams on lake area changes is greater than that of glaciers The impact on the lake area changes,for the lake water level changes in different watersheds,of which the glaciers without glaciers only rely on stream replenishment,the watershed variability of lakes in stream basins is higher than that of lakes with glaciers replenishment,indicating that the impact of lake water level changes on streams The recharge accounted for the main factor,and the impact of glaciers on water level changes is relatively small.(5)Changes in the lake area,water level,and water volume of the Tibetan Plateau are affected by many factors,among which temperature and precipitation are two very important factors.The average annual temperature of the Tibetan Plateau has shown a significant growth trend from 1970 to 2018,and the annual precipitation has also shown an increasing trend;from the overall changes in the lake area,water level,and water volume of different types of watersheds to the annual average temperature and the annual precipitation rate From the perspective of the change trend between the two,the temperature change is more consistent with the change trend of lake area,lake water level,and lake water volume. |
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