Determination method of planar potential replenishment quantity of underground water based on isotope rainfall effect

The invention discloses a determination method of planar potential replenishment quantity of underground water based on an isotope rainfall effect. The method comprises the steps that a vadose zone interception threshold model is established; a determined rainfall material and an underground water material are brought into the vadose zone interception threshold model for solving; vadose zone interception water quantity, namely minimum replenishment rainfall of the underground water is obtained; and then the potential replenishment quantity of the underground water is calculated. The method achieves replenishment of hydrogeological underground water, provides a novel reliable method, promotes development of a hydrogeological discipline, scientifically and reasonably determines the planar potential replenishment quantity of regional underground water, facilitates optimal allocation of an underground water resource, provides reliable data for water resource management, provides more detailed scientific support for further establishing economic development and ecological protection measures, can be directly applied to calculation and evaluation of a regional underground water resource, improves the applicability of a determination result, and avoids a possible error in a scale conversion process of the determination result.