Groundwater recharge level estimation from rainfall record probability match methodology

Groundwater reservoirs’ assessment and management studies present more difficulties compared to surface water resources, because their storage media are geological formations, which have spatial heterogeneities that cannot be expressed by empirical or deterministic methodologies easily. Especially, their recharge possibilities are dependent not only on the precipitation features, but also on uncertainties including heterogeneous porosity, specific yield, storage, hydraulic conductivity, permeability and transmissivity quantities. The best way to treat such uncertainties is through the probability distribution function (PDF) methods, which reflect the spatial and temporal randomness in the meteorological and hydrogeological variabilities. In general, this paper presents temporal PDF behaviors of the rainfall variation and groundwater level fluctuation in addition to the probabilistic correlation between them. For this purpose, the cumulative distribution functions (CDF) of rainfall and groundwater level rise departures are considered from respective mean values. The two CDFs are related to each other on the valid assumption that the more the rainfall cumulative departure from the mean the more is the groundwater fluctuation. The application of this probabilistic methodology is presented to available data from the south eastern part of Turkey.