基于GRACE重力卫星数据非洲大陆水储量的时空变化分析

发布时间：2018-03-31 14:00

本文选题：非洲大陆　切入点：GRACE　出处：《浙江大学》2017年硕士论文

【摘要】：基于GRACE重力卫星观测区域水储量的时空变化有利于探索区域水圈变化和水资源平衡情况,成为展现中长空间尺度水储量变化情况的一个新方式。近年来,气候变化、沙漠扩张以及经济发展都对非洲大陆的水储量分布造成了极大的影响。然而非洲大陆的水储量变化信号强度不如南极洲、格陵兰岛和亚马逊河流域等区域,非洲地区基于GRACE的水储量变化研究为数不多,而且使用数据的时间跨度和版本都有所不足,研究范围也不够全面,变化明显地区研究深度有限。温度带、干燥度、地形、植被等格局分布都会影响水储量的变化,非洲大陆幅员辽阔,借助格局数据将非洲分为5个地理分区:以沙漠为主的北部荒漠区、由荒漠向草原演变的中北过渡区、以刚果盆地为主的中部盆地区、以东非大裂谷为主的东部裂谷高原区和最南端的南部高原区。本文采用了 2003年1月份到2014年12月份之间的重力卫星GRACE.等效水高数据反.演非洲大陆各地理分区水储量时空变化,得到非洲大陆年内逐月变化和各地理分区年际变化。为了保证反演结果正确,选择GLDAS-NOAH数据进行验证,两种数据相关性很好。非洲大陆水储量年内最明显的变化是范围涉及中北过渡区、中部盆地区和东部裂谷高原区的旱/雨季现象,地理分区年际趋势分析显示2003～2014年非洲大陆除了中部盆地区外基本处于亏损趋势。叠加2003～2014年的等效水高数据,年际亏损最明显的地方分别对应着尼罗河流域、北部荒漠区和中北过渡区之间的萨赫勒地带以及南部高原区西北部的卡拉哈里盆地三个地理单元,还有约翰内斯堡-比勒陀利亚地区,结合DDI荒漠化指数数据、降水数据和夜光数据对这些亏损明显的地区深入研究,分析引起水储量变化的原因。结果表明:(1)尼罗河流域上游引起水储量亏损的主要原因是坦桑尼亚境内的富特文勒冰川面积在缩减,肯尼亚的冰盖也大范围融化消退,导致赤道湖泊群水位下降,继而引起水储量的亏损。中游水储量变化和DDI荒漠化指数呈强相关,亏损主要是由荒漠化扩张引起。流域内国家水储量亏损严重,"水政治"问题依然存在着,水资源管理需要流域内各国加强合作。(2)结合GRACE数据、DDI荒漠化指数数据和降水数据,世界上荒漠化扩张最严重的萨赫勒地带和卡拉哈里盆地水储量呈现逐年亏损。非洲大陆荒漠化治理严重滞后,本文选取的荒漠化治理效果良好的陕西荒漠化监测区,荒漠化治理使得水储量得到一定程度的恢复。基于GRACE研究荒漠化为监测荒漠化提供了新的视角。(3)夜光数据显示约翰内斯堡-比勒陀利亚地区是非洲大陆亮度最高,范围最广的经济带。水储量变化和夜光影像灰度值变化呈负相关,水储量小幅度亏损,且对比区研究结果显示经济带年内水储量变化和降雨的相关性减弱,经济发展影响了该地区的水储量变化。
[Abstract]:The temporal and spatial variation of regional water reserves observed by GRACE gravity satellite is beneficial to the exploration of regional hydrosphere change and water resources balance, and it becomes a new way to show the variation of water reserves on medium and long spatial scale. In recent years, climate change has been observed. Desert expansion and economic development have had a significant impact on the distribution of water reserves on the continent. However, the continent's water reserves change signals are not as strong as those in Antarctica, Greenland and the Amazon River basin. There are few studies on water reserve changes based on GRACE in Africa, and the time span and version of the data used are insufficient, the scope of the study is not comprehensive enough, the study depth of obvious regions is limited, the temperature zone, the dryness, the topography, the temperature zone, the dryness, the topography, The distribution of vegetation and other patterns will affect the change of water reserves, and the African continent has a vast territory. With the help of pattern data, Africa is divided into five geographical subzones: desert desert in the north, and the transitional region from desert to steppe in central and northern China. The central basin region, dominated by the Congo basin, The eastern rifting plateau and the southernmost southern highland region, dominated by the Great Rift Valley of East Africa, are used in this paper. The gravity satellite GraCE.Equivalent water height data from January 2003 to December 2014 are used to invert the equivalent water height data. Temporal and spatial variation of water reserves, In order to ensure that the inversion results are correct, the GLDAS-NOAH data are selected for verification. The most obvious change in the continent's water reserves during the year is the drought / rainy season in the north-central transitional region, the central basin region and the eastern rift valley plateau. The annual trend analysis of geographical regions shows that the African continent is basically in a deficit trend except for the central basin area from 2003 to 2014. When the equivalent water height data from 2003 to 2014 are superimposed, the most obvious interannual losses are corresponding to the Nile basin, respectively. The Sahelian belt between the northern desert and the north-central transitional zone and the three geographic units of the Kalahari basin in the north-west of the southern highlands, as well as the Johannesburg-Pretoria region, combined with DDI desertification index data, The precipitation data and the nocturnal light data deeply studied these areas where the losses were obvious. The results show that the main reason for the loss of water reserves in the upper reaches of the Nile River Basin is the shrinking area of the Futvinle Glacier in Tanzania and the widespread melting of the Kenyan ice sheet. As a result, the water level of the equatorial lake group drops and the water reserves are depleted. The variation of the water reserves is strongly correlated with the DDI desertification index. The deficit is mainly caused by the expansion of desertification. The water reserves of the countries in the basin are seriously depleted, and the problem of "water politics" still exists. The water resources management needs the countries in the basin to strengthen their cooperation. (2) combined with the GRACE data, the desertification index data and precipitation data are used. The water reserves in the Sahel and Kalahari basins, which have the most serious desertification expansion in the world, are losing money year by year. The desertification control area in Shaanxi Province, which has a good effect on desertification control, is seriously lagging behind in the African continent. Desertification control has restored water reserves to a certain extent. Based on the GRACE study, desertification provides a new perspective for desertification monitoring.) Night-light data show that the Johannesburg-Pretoria region is the continent with the highest brightness. The variation of water reserves is negatively correlated with the change of the gray value of nocturnal images, and the loss of water reserves is small. The results of the comparative study show that the correlation between the changes of water reserves and rainfall in the economic zones is weakened during the year. Economic development has affected changes in water reserves in the region.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P332

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