2002-2020年黄土高原土壤水变化及其相关性分析

土壤水作为植物耗水最主要的来源,其变化对整个生态系统都有重要影响。利用GRACE卫星数据与GLDAS-NOAH模型,分析2002—2020年黄土高原土壤水时空变化规律,并结合GEE平台2002—2020年的MODIS NDVI产品数据集、与2000—2017年降水资料对土壤水的变化进行相关性分析,使用M—K检验法对趋势进行检验,结果表明:(1)2002—2020年GRACE等效水高(毫米水柱高)变化月均值为(-7.56±4.38)mm,从2008年开始呈现显著减少趋势。(2)2000—2020年0—10 cm土层土壤水呈不显著增加趋势,10—40,40—100,100—200 cm呈不显著变化趋势,2012—2020年200 cm以下土层土壤水呈显著减少趋势。(3)随着土层深度的增加,黄土高原2000—2017年的降水与土壤水的相关性在显著降低。相关性系数从0—10 cm时的0.581降低到100—200 cm时的0.099。而将2002—2020年的200 cm以下土层土壤水与NDVI变化分析其相关性系数为-0.805~*,为显著负相关关系。研究结果阐述了黄土高原土壤水的变化规律,揭示了降水和NDVI变化与其的相关性联系,为下一步黄土高原的植被恢复提供了理论支撑。

Soil Water Change and Its Correlation Analysis in the Loess Plateau from 2002 to 2020

Soil water is the main source of plant water consumption, and its change has an important effect on the whole ecosystem. Using GRACE satellite data and GLDAS-NoAH model, this study analyzed the spatial and temporal variation of soil water in the Loess Plateau from 2002 to 2020. Combined with the from 2002 to 2020 MODIS NDVI product data set of GEE platform and the precipitation data from 2000 to 2017, the correlation analysis of soil water changes was carried out for comparative analysis, and the M-K test method was used to test the change trend. The results showed that:(1) The monthly mean of equivalent water height (mm water column height) of GRACE from 2002 to 2020 was (-7.56±4.38) mm, and showing a significant decreasing trend from 2008. (2) From 2000 to 2020, soil water in the 0-10 cm soil layer showed no significant increase trend, while it showed no significant change trend in the 10-40, 40-100 and 100-200 cm soil layers, and it showed a significant decrease trend in the 200 cm soil layer from 2012 to 2020. (3) With the increasing of soil depth, the correlation between precipitation and soil water decreased significantly in the Loess Plateau from 2000 to 2017. Correlation coefficient decreased from 0.581 of 0-10 cm soil layer to 0.099 of 100-200 cm soil layer. The correlation coefficient between NDVI and soil water of the soil layer deeper than 200 cm 2002 to 2020 was -0.805, which was a significant negative correlation. The results revealed the change law of soil water in the Loess Plateau, revealed the correlation between precipitation and NDVI changes and soil water, which could provide a theoretical support for the next step of vegetation restoration in the Loess Plateau.