Accurate groundwater recharge estimates are vital for the management of groundwater resources. The watertable fluctuation method (WTFM) is one of the most widely used techniques for estimating distributed recharge. This is likely due to the simplicity of its formulation and the limited input data requirements, which include groundwater level measurements and a specific yield estimate. The method is presented in alternative forms within published accounts of its use, including adaptations for non-ideal situations (e.g., aquifers subjected to extensive pumping). This review summarises the development of the WTFM and its variants, applied to the estimation of distributed recharge, and compares resulting recharge estimates from alternative forms of the method with other recharge estimation techniques. The review finds that the WTFM has been modified to account for shallow watertable conditions, deep unsaturated zones, groundwater pumping, seasonal variations in evapotranspiration, and aquifers with hydraulic properties that vary with depth. A key component of the WTFM is the projection of the antecedent recession curve to account for groundwater discharge during periods of watertable rise, for which there are multiple approaches. The best choice for projecting the recession curve remains unclear. Opportunities to develop the WTFM and improve its reliability include modifications to account for common boundary effects (e.g., proximity to rivers, etc.), evaluating the accuracy of recession curve projection techniques, assessing the spatial scale for which WTFM estimates of recharge apply, and incorporating more complex storage terms into the WTFM. Despite the extensive use of the WTFM, systematic testing has been limited and is therefore needed, including for the many alternative forms of the WTFM.

中文翻译：

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地下水位波动补给估算方法：综述


准确的地下水补给估算对于地下水资源的管理至关重要。地下水位波动法（WTFM）是估计分布式补给最广泛使用的技术之一。这可能是由于其公式的简单性和有限的输入数据要求，其中包括地下水位测量和具体的产量估计。该方法在已发表的使用说明中以替代形式呈现，包括对非理想情况的适应（例如，含水层受到广泛抽水）。本综述总结了应用于分布式补给估算的 WTFM 及其变体的发展，并将该方法替代形式的补给估算结果与其他补给估算技术进行了比较。审查发现，WTFM 已经过修改，以考虑浅层地下水位条件、深层非饱和区、地下水抽水、蒸散量的季节变化以及水力特性随深度变化的含水层。 WTFM 的一个关键组成部分是预测先前的衰退曲线，以考虑地下水位上升期间的地下水排放，对此有多种方法。预测衰退曲线的最佳选择仍不清楚。开发 WTFM 并提高其可靠性的机会包括进行修改以考虑常见边界效应（例如，靠近河流等）、评估衰退曲线投影技术的准确性、评估 WTFM 补给估算适用的空间尺度，以及将更复杂的存储术语纳入 WTFM。 尽管 WTFM 被广泛使用，但系统测试仍然有限，因此需要进行系统测试，包括针对 WTFM 的许多替代形式。