Data from the Gravity Recovery and Climate Experiment (Grace) satellite and stations were used to estimate variations of the monthly groundwater level in the Zayanderud basin, Iran, over the period 2000–2018. In addition, the annual and seasonal storage of groundwater in this basin was estimated and verified using Grace satellite data, and compared with data from the previous rainfall. The results showed that the current groundwater level depends on the amount of rainfall in past years. When rainfall is on a downtrend, the trend of underground water storage fluctuations is affected by rainfall to a greater extent. In addition to the time trend, the pattern of the normalised difference vegetation index (NDVI) depends on the amount of groundwater storage variations in the Zayanderud basin. The lowest NDVI (0·078) in 2016 coincided with the lowest amount of underground water storage and recharge rate (27·36 cm). Statistical correlation analysis of Grace satellite data and recorded data from wells indicated a root mean square error of 2·23 cm, a mean absolute error of 3·28 cm and a mean bias error of 1·02 cm on the seasonal scale. The results show that Grace data can provide a good understanding of long-term variations when studying the relationship between groundwater level and rainfall, especially in large basins.

中文翻译：

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利用Grace卫星数据得出的地下水位变化与降雨之间的关系

利用重力恢复和气候实验（Grace）卫星和测站的数据估算了伊朗Zayanderud盆地2000-2018年期间每月地下水位的变化。此外，利用格蕾丝（Grace）卫星数据估算并验证了该流域的地下水的年度和季节性储量，并将其与先前降雨的数据进行了比较。结果表明，当前的地下水位取决于过去几年的降雨量。当降雨呈下降趋势时，地下水储量波动的趋势在很大程度上受到降雨的影响。除了时间趋势外，归一化植被指数（NDVI）的模式还取决于Zayanderud盆地的地下水储量变化量。2016年的最低NDVI（0·078）与最低的地下水蓄水和补给率（27·36 cm）相吻合。Grace卫星数据和井中记录数据的统计相关性分析显示，季节性尺度的均方根误差为2·23 cm，平均绝对误差为3·28 cm，平均偏差为1·02 cm。结果表明，当研究地下水位与降雨之间的关系时，尤其是在大盆地，Grace数据可以很好地了解长期变化。