Adequate management of water resources in aquifer systems implies knowledge of the different parameters of hydrological balance. However, only limited data exist for many aquifers, which lead to the production of hydrological models with high levels of uncertainty. This research estimates spatially and temporally the groundwater storage change and the storage coefficient in unconfined aquifers and under uncontrolled conditions by means of gravimetric data and validates the estimates by two procedures based on piezometric data. The application of the three procedures was carried out in an aquifer located in the Etla Valley, Oaxaca, Mexico. Piezometric data and gravitational field measurements from October 1996 and May 2018 were employed. Groundwater storage change was calculated via piezometry, residual Bouguer anomaly and gravimetry. The piezometric and gravimetric procedures estimated similar spatial distributions of groundwater recharge and discharge areas but different reductions in groundwater storage volume. The gravimetric method estimated a loss that was 50% lower than that produced by the procedures based on piezometry. The storage coefficient varied spatially in a range between − 0.22 and 0.30, assuming a theoretical relationship between gravimetric and piezometric variations based on the Bouguer slab model.

含水层系统中水资源的充分管理意味着了解水文平衡的不同参数。然而，许多含水层只存在有限的数据，这导致产生具有高度不确定性的水文模型。本研究通过重力数据在空间和时间上估算了无承压含水层和不受控制条件下的地下水储存变化和储存系数，并通过基于测压数据的两个程序验证了估算。这三个程序的应用是在位于墨西哥瓦哈卡州埃特拉河谷的一个含水层中进行的。使用了 1996 年 10 月和 2018 年 5 月的压力测量数据和重力场测量值。通过测压法、残余布格异常和重力法计算地下水储量变化。测压法和重力法估计地下水补给和排放区域的空间分布相似，但地下水储存量的减少不同。重量法估计的损失比基于测压法的程序产生的损失低 50%。假设基于布格板模型的重力和压力变化之间存在理论关系，存储系数在 - 0.22 和 0.30 之间的空间范围内变化。