Abstract
Specific storage ( S S ) has considerable predictive importance in the modelling of groundwater systems, yet little is known about its statistical distribution and dependency on other hydrogeological characteristics. This study provides a comprehensive overview and compiles 430 values of S S from 183 individual studies, along with complementary hydrogeological information such as estimation methods, lithology, porosity, and formation compressibility. Further evaluation of different approaches to determine and utilize S S values for numerical groundwater modelling, along with the scale and source of uncertainty of different measurement methods, was carried out. Overall, S S values range across six orders of magnitude (from 3.2 × 10 –9 to 6 × 10 –3 m –1 ) with a geometric mean of 1.1 × 10 –5 m –1 and the majority (> 67%) of values are in the order of 10 –5 and 10 –6 m –1 . High S S values of ~10 –4 m –1 were reported for glacial till and sandy lithologies, particularly for shallow and thin strata where leakage may obscure the estimation of S S . A parallel assessment of 45 transient regional-scale groundwater models reveals a disconnect between findings of this study and the way S S is treated in practice, and that there is a lack of foundational S S data to conduct quantitative uncertainty analysis. This study provides the first probability density functions of S S for a variety of lithology types based on the field and laboratory tests collated from the literature. Log transformed S S values follow a Gaussian/normal distribution which can be applied to evaluate uncertainties of modelling results and therefore enhance confidence in the groundwater models that support decision making.