利用GRACE卫星重力数据监测关中地区地下水储量变化

关中地区作为一带一路重要的工农业发达地区之一，开展针对该地区地下水储量变化的监测和分析工作对揭示地下水储量变化特征与经济社会发展具有重要现实意义.本文基于2003—2014年GRACE卫星重力场模型数据，采用组合滤波及单一尺度因子方法反演了关中地区陆地水储量变化，扣除GLDAS地表水平均结果，对关中地区地下水储量变化进行了监测分析.将陆地水储量变化与GLDAS进行相关性分析，将地下水储量变化与WGHM地下水模型及实测地下水位结果进行对比分析.研究结果表明：①关中地区陆地水变化与GLDAS模型结果具有较强的相关性，相关系数多数大于0.7，其中与模型平均结果的相关系数可达0.8.② 2003—2008年关中地区地下水呈正增长趋势，增加速率为0.25 cm·a^-1，与同期实测数据变化趋势一致；但2003—2013年地下水存在长期亏损，亏损速率为-0.37 cm·a^-1等效水高，这与同时期WGHM估算结果-0.35 cm·a^-1十分吻合.③关中地区地下水存在明显的年变化特征，在2003—2014年期间地下水减少速率为-0.44 cm·a^-1，与该地区降雨量有较好的一致性，在降雨偏少的2008、2012和2013年，地下水也显著减少.

Monitoring groundwater storage variations in the Guanzhong area using GRACE satellite gravity data

Guanzhong is one of the important industrial and agricultural developed areas in ‘One Road and One Belt’. It is necessary to monitor and analyze groundwater storage (GWS) variations in this area to reveal the characteristics of GWS, which is of great importance for economic and social development. Firstly, based on the gravity field model from the Gravity Recovery and Climate Experiment (GRACE) satellite data from 2003 to 2014, the combined filter and method of single-scale factor are applied to invert the terrestrial water storage (TWS) variations in the Guanzhong area. Then by subtracting the results of GLDAS average surface water from TWS, GWS variations in this area are determined. Finally, the correlation between TWS and GLDAS is analyzed, and the GWS variations are compared with that from the WGHM groundwater model and well observations. The results show that (1) the TWS variations in the Guanzhong area have a strong correlation with the GLDAS model (VIC, NOAH, CLM, and MOSIC). The most correlation coefficients between them are greater than 0.7, whereas the correlation coefficient between the model average and TWS is up to 0.8. (2) During 2003 to 2008, GWS in the Guanzhong area showed a positive growth trend, and the increase rate was 0.25 cm·a^-1, which is consistent with the trend of well observations in the same period. However, there was a long-term depletion of GWS from 2003 to 2013, and the depletion rate is -0.37 cm·a^-1, which agrees well with the WGHM estimation result of -0.35 cm·a^-1 for the same period. (3) There are obvious annual variation characteristics of GWS in the Guanzhong area. The rate of GWS depletion during 2003 to 2014 was -0.44 cm·a^-1, which was in good agreement with the rainfall in this area, while during the drought years, i.e., 2008, 2012 and 2013, GWS also decreased significantly.