青藏高原典型内流-外流盆地水力联系潜在变化研究

Monitoring of hydraulic connection changes in typical endorheic-exorheic basins in the Qinghai-Tibet Plateau

近几十年来,随着全球气候变暖,冰川退缩、冻土消融、河流流量增加和湖泊扩张等成为青藏高原科学研究备受关注的热点问题。高原水系统的这些变化催生了内流湖泊漫溢并与外流水系重建水力联系的风险。为了探究青藏高原内流区湖盆与外流区水系重建水力联系的潜在风险,本文以卫星遥感数据和气象再分析数据为数据源,采用地统计分析方法,筛选出了青藏高原内流区26个与外流区具有潜在水力联系的湖泊流域盆地,并且分析了这些湖盆内的主要湖泊面积的变化以及与区域内关键气象参量(降水、气温和蒸发)之间的相关性特征。研究表明,研究遴选出的内流盆地湖泊水体整体扩张趋势显著。不同区域的湖泊水面面积变化与气温、降水等气象要素之间具有明显的差异性。其中,与气象要素变化具有强相关性(R^(2)>0.5)的盐湖、班公错、泽错和雀莫错4个湖泊中,盐湖已于2019年与长江源支流水系重建水力联系并外溢;其他3个湖泊在无突发极端气象或地质灾变的情况下,在未来30年内无外溢的风险。本研究有助于理解在全球气候变化影响下,青藏高原河湖水系的变化过程规律及科学地预防和应对潜在的灾害风险。

In recent decades,climate change caused glacier melting and hydrological cycle acceleration has re⁃sult in expansion of many lakes in the world,which may trigger the reorganization of endorheic and exorheic lake and river systems,and even lead to geological hazards such as lake outburst and sudden floods.Under the background of global warming,the retreat of glaciers,the melting of permafrost,the increase of river flow,and the expansion of lakes have become the hot issues of scientific research on the Qinghai-Tibet Plateau.The signifi⁃cant changes on the plateau water system have given rise to the risk of overflow of endorheic lakes and recon⁃struction of hydraulic connection with outflow river systems.In this paper,in order to explore the potential risk regions for the reconstruction of hydraulic connection between the endorheic lake basin and the drainage system in the outflow region of the Qinghai-Tibet Plateau,the JRC Yearly Water Classification History v1.3,ETOPO1 DEM data,Landsat 8 satellite remote sensing data(2019—2020),China’s regional surface meteorological ele⁃ment driven dataset(1979—2018),and the Qinghai-Tibet Plateau monthly average surface evapotranspiration dataset(2001—2018)are used as the data sources,the runoff river network in the study area is extracted by us⁃ing ArcGIS hydrological analysis tool,and 26 endorheic lake basins with potential hydraulic connection with the exorheic basins of the Qinghai-Tibet Plateau are obtained.The Pettitt’test,M-K trend analysis,and Pearson correlation analysis are used to analyze the hydrological and meteorological parameters change rules on the 26 en⁃dorheic lake basins.The analysis results showed that the abrupt change years for most of lakes are between 2000 and 2003,and lake water area in 17 lake basins is in an increasing trend from 1984 to 2018.Among them,the changes of water area of Yanhu Lake,Pangong Tso Lake,Zecuo Lake,and Quemocuo Lake are significantly re⁃lated to the changes of meteorological parameter data(R^(2)larger than 0.5).Then the correlation model between the water area and meteorological factors of the 4 lakes is constructed,and the changes of the lake water area with meteorological data in recent 30 years are analyzed.On this basis,the impact of regional precipitation,tem⁃perature and other parameters changes on the lake water area in the next 30 years(before 2050),and the reorga⁃nization possibility of the hydraulic connection between the 4 related lake basins with the exorheic river systems are analyzed.The following conclusions are obtained:(1)the surface water area of the 17 endorheic lakes expe⁃riences significant increasing trends from 1984 to 2018;(2)the correlation between the change of lake surface area and meteorological factors is different in difference places on the Qinghai-Tibet Plateau.The change of the water surface area of the Yanhu Lake and Quemocuo Lake in Qinghai Province in the east of the plateau is main⁃ly related to temperature and precipitation,while the change of the water surface area of Pangong Tso and Zecuo lakes in the higher altitude of the Tibet Autonomous Region in the west of the plateau is mainly related to the change of temperature;(3)the future prediction results of the water surface areas of the Yanhu,Quemocuo,Pangong Tso,and Zecuo lakes show that,except the Yanhu Lake which had rebuilt its hydraulic connection with a tributary of the Yangtze River in 2019,Pangong Tso,Zecuo,and Quemocuo lakes haven’t risk of over⁃flow before 2050.This study is helpful to understand the change process of lake and river water systems under the influence of global climate change,it is also helpful to scientifically prevent and respond to potential lake out⁃burst disaster risks.