GRACE/GRACE-FO揭示黄河上游2002-2022年GWS及可持续性时空演化

Spatiotemporal Changes of GWS Changes and Their Sustainability in the Upper Reaches of the Yellow River Basin from 2002 to 2022 Revealed by GRACE/GRACE-FO Observations

开展黄河流域上游地下水储量(groundwater storage,GWS)时空变化及可持续性时空演化特征研究,可为黄河流域水资源可持续合理开发提供有力的参考依据。利用GRACE(gravity recovery and climate experiment)和GRACE-FO(GRACE follow on)重力卫星Mascon和球谐数据,联合先验水文模型,反演估算了黄河流域上游2002-04—2022-12陆地水储量及GWS变化时空演化特征,通过计算区域水资源可持续性指数(sustainability index,SI)评估该区域地下水可持续性概况,并探讨了降雨量变化、归一化植被指数(normalized difference vegetation index,NDVI)、蒸散发量(evapotranspiration,ET)与区域GWS变化的相关性及其贡献度。结果表明,研究区域GWS变化以约-3.89±0.37 mm/a速率呈整体下降趋势,在空间上呈现出明显的南、北量值差异分区的特性,与实测水井监测结果较一致(相关度约为0.73);研究时段内区域地下水几乎均处于重度不可持续状态,空间上可持续性也呈现出自南向北逐渐降低的趋势,平均可持续性指数仅为0.38;贡献度量值大小显示出NDVI对研究区域GWS变化产生的影响最大,ET次之,降雨量影响最小;NDVI、ET与区域GWS变化呈显著负相关关系(相关系数分别约为-0.76和-0.77),黄河流域上游南、北部降雨与相应GWS变化呈正相关关系(相关系数分别约为0.54和0.50)。

Objectives:Studying the spatiotemporal changes of groundwater storage(GWS)and its sustainable spatiotemporal evolution characteristics in the upper reaches of the Yellow River Basin can provide a valuable reference for the sustainable and rational development of water resources in the Yellow River Basin.Methods:The changes of terrestrial water storage(TWS)and GWS in the upper reaches of the Yellow River Basin from April 2002 to December 2022 were estimated using Masson data and spherical harmonic(SH)data from GRACE(gravity recovery and climate experience)and GRACE-FO(GRACE follow on)gravity satellites,combined with prior hydrological models,and their temporal and spatial variation characteristics were also analyzed.The sustainability index(SI)of water resources in the study area was further calculated to evaluate the sustainability of regional groundwater.And the correlation and contribution of precipitation change,normalized difference vegetation index(NDVI),evapotranspiration(ET)and regional GWS were discussed.Results:The change of GWS in the study area showed an overall downward trend at a rate of approximately-3.89±0.37 mm/a,and showed obvious spatial characteristics of the difference between the southern and northern values,which was consistent with the monitoring results of the measured wells(correlation was approximately 0.73).During the study period,the regional groundwater was almost in a state of severe unsustainability,and the spatial sustainability also gradually decreased from south to north,with an average sustainability index of only 0.38.The size of the contribution measure shows that NDVI has the greatest impact on the change of GWS in the study area,ET has the second highest impact,and the rainfall has the smallest;there was a significant negative correlation between NDVI,ET and regional GWS changes(correlation coefficients were approximately-0.76 and-0.77,respectively).The rainfall in the south and north of the study area was positively correlated with the corresponding GWS changes(correlation coefficients were approximately 0.54 and 0.50,respectively).Conclusions:This study effectively evaluated the changes of TWS and GWS in the upper reaches of the Yellow River Basin over the past 20 years,and reasonably evaluated the spatiotemporal distribution characteristics of groundwater sustainability in the upper reaches of the Yellow River,as well as the correlation between external influences and GWS.