[1] This study has simulated the terrestrial hydrology associated with different climate, landscape, and permafrost regime scenarios for the field case example of the relatively well characterized coastal catchment of Forsmark, Sweden. The regime scenarios were selected from long-term simulation results of climate, topographical, shoreline, and associated Quaternary deposit and vegetation development in this catchment with a time perspective of 100,000 years or more and were used as drivers for hydrological simulations with the three-dimensional model MIKE SHE. The hydrological simulations quantify the responses of different water flow and water storage components of terrestrial hydrology to shifts from the present cool temperate climate landscape regime in Forsmark to a possible future Arctic periglacial landscape regime with or without permafrost. The results show complexity and nonlinearity in the runoff responses to precipitation changes due to parallel changes in evapotranspiration, along with changes in surface and subsurface water storage dynamics and flow pathways through the landscape. The results further illuminate different possible perspectives of what constitutes wetter/drier landscape conditions, in contrast to the clearer concept of what constitutes a warmer/colder climate.

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In the paper "Chloride migration in heterogeneous soil, 2, Stochastic modeling" by G. Destouni et al. (Water Resources Research, 30(3), 747-758, 1994), equation (7) should read as follows: •0 t s(t, z)/p,4 = exp [-kitiSm(t; z) + 3'(t, T)Sm(T; Z) d, (7a) y(t, r) = kik2r exp I-kit-k2t + k2r] ß ]•[k•k2,(t-,)]H(t-,) (7b) in which •-= ,(z) is the arrival time to z of an indivisible solute particle that is advected along an individual streamline within a soil monolith. The function Sm(t; Z) (equation (8) or (9)) quantifies the relative frequency of arrival times •-= t in the considered monolith with mean arrival time T = ZOm/qs. Note also that in (3b) and (7b) •[k•k2r(t-r)] is a Bessel function with argument k•k•,(t-,) and not a multiplication of two functions.

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This paper describes solute transport modeling carried out as a part of an assessment of the long-term radiological safety of a planned deep rock repository for spent nuclear fuel in Forsmark, Sweden. Specifically, it presents transport modeling performed to locate and describe discharge areas for groundwater potentially carrying radionuclides from the repository to the surface where man and the environment could be affected by the contamination. The modeling results show that topography to large extent determines the discharge locations. Present and future lake and wetland objects are central for the radionuclide transport and dose calculations in the safety assessment. Results of detailed transport modeling focusing on the regolith and the upper part of the rock indicate that the identification of discharge areas and objects considered in the safety assessment is robust in the sense that it does not change when a more detailed model representation is used.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-013-0395-5) contains supplementary material, which is available to authorized users.

The statistics of chloride transport through 29 undisturbed soil monoliths (20 cm in diameter and 1 rn long, sampled from a field plot of 15 x 175 m 2) were evaluated in a controlled laboratory experiment. Although the field soil {loamy sand) was relatively homogeneous with regard to texture, the individual monoliths showed large and irregular variability in their soil characteristics and in their flow and transport properties. The distribution of the specific discharge of water could be quantified by a birnodal distribution; the horizontal correlation length for the specific discharge of water was estimated to about 10 m. The ratio between the arrival time of the peak in chloride concentration and the water residence time given by the measured flow parameters indicated a mobile water content that was smaller than the measured water content. The large variability in hydraulic conductivity in both the vertical and horizontal direction, and the agreement between the present hydraulic conductivity measurements and earlier measurements in the field area, indicate that the partition of the measured water content between mobile and relatively immobile water was an effect of the soil structure rather than a boundary effect.

This paper presents an analysis of present and future hydrological conditions at the Forsmark site in Sweden, which has been proposed as the site for a geological repository for spent nuclear fuel. Forsmark is a coastal site that changes in response to shoreline displacement. In the considered time frame (until year 10 000 ad), the hydrological system will be affected by landscape succession associated with shoreline displacement and changes in vegetation, regolith stratigraphy, and climate. Based on extensive site investigations and modeling of present hydrological conditions, the effects of different processes on future site hydrology are quantified. As expected, shoreline displacement has a strong effect on local hydrology (e.g., groundwater flow) in areas that change from sea to land. The comparison between present and future land areas emphasizes the importance of climate variables relative to other factors for main hydrological features such as water balances.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-013-0394-6) contains supplementary material, which is available to authorized users.

The results of an extended analysis of the chloride breakthrough curves (BTCs) obtained from transport experiments on undisturbed soil monoliths previously reported by Sassner et al. (1994) are discussed. Parameter values for different forms of the advection‐dispersion equation (ADE) were obtained by curve‐fitting using the nonlinear least‐squares optimization code CXTFIT developed by Parker and van Genuchten (1984). Good fits to the experimental BTCs from the individual soil monoliths were obtained for three different forms of the ADE, allowing for anion exclusion, immobile water, and both of these processes, respectively. Although the more complex forms of the ADE possess more flexibility to provide a slightly more refined fit to the individual breakthrough curves, larger uncertainty is associated with the fitted parameter values. Due to the limited amount of information manifested in the BTCs it is not possible on the basis of this information to distinguish which of the models is physically more meaningful. Furthermore, when more parameters are included in the optimization procedure, the resulting values are more uncertain. The same ADE models were also fitted with equally good results to a hypothetical large‐scale BTC derived by flux‐averaging the responses from the individual monoliths. However, regardless of the form of the ADE used, the resulting parameter values for the large‐scale transport (i.e., not only the dispersivity value that is expected to increase) were inconsistent with the corresponding parameter values obtained for the individual BTCs. This supports previous indications that ADE models may not be accurate for predicting large‐scale transport in heterogeneous soil systems corresponding to e.g. the scale of an agricultural field or a grid element in a numerical catchment model because model parameters are not determinable from independent measurements on a scale corresponding to a practical manageable core size or to standard intrumentation.