Laboratory experiments were performed on chalk samples from Denmark and Israel to determine diffusion and distribution coefficients. Batch tests were used to define sorption isotherms for naphthalene and o-xylene. Linear sorption isotherms were observed and described with Henry-isotherms. Because of the high purity and low contents of clay minerals and organic carbon, Danish and white Israeli chalk generally have low retardation capacities. Contrarily, gray Israeli chalk, with organic carbon fractions as high as 1.092%, remarkably retards organic contaminants. The K(OC) concept is not applicable to predicting distribution coefficients based on the organic carbon content in the chalk samples. Effective diffusivities of o-xylene, naphthalene, and several artificial tracers were determined using through-diffusion experiments. Based on measured diffusion coefficients and available literature values, a chalk specific exponent of 2.36 for Archie's law was derived, allowing a satisfactory estimate of relative diffusivities in chalk. A field-scale tracer test with uranine and lithium was performed in the Negev desert (Israel) to examine the transferability of diffusivities determined on small rock samples in the laboratory. Due to low recovery rates of the tracer, a modified single fissure dispersion model was used for inverse modeling of the breakthrough curves. Resulting diffusivities deviate insignificantly from the laboratory values, which are considered to be representative for the investigated part of the aquifer and applicable in transport models.

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More than 1,000 constant discharge and stepdrawdown pumping tests each were analysed for an area underlain by Basement granite in Limpopo Province, South Africa. The climate and topography vary greatly over the study area, with fairly constant prevailing neotectonic stresses. The pumping tests were analysed via the methods of Theis (Am Geophys Union Trans 14 (2):519-524, 1935), Cooper and Jacob (Am Geophys Union Trans 27:526-534, 1946), Logan (Groundw 2:35-37,1964) and Birsoy and Summers (Groundw 18:137-146, 1980). Transmissivities obtained from the different methods were assigned a scenario of high ([100 m 2 /day), intermediate (10-100 m 2 /day) or low (\10 m 2 /day). These scenarios were superimposed on models controlling flow (shear zones, open structures, closed structures, contacts and the weathered aquifer) and settings (inherent prevailing climatic and neotectonic conditions) to evaluate the controls of groundwater occurrence in Basement terrain.