Generic soil descriptions for modelling water and chloride dynamics in the unsaturated zone based on Swedish soils

Information about soil hydraulic properties is a prerequisite for modelling water and solute dynamics in the unsaturated zone. Providing that this information is available and the uncertainty is within an acceptable range, computer models can be helpful tools in quantifying environmental effects. This study describes the water retention curve and hydraulic conductivity for three soil types: clay, glacial till and sand. These soils originated from a Swedish database containing 2200 measured soil layers representing 260 soil profiles. A simulation experiment was conducted where daily variations in water and chloride were simulated for a 20-year period in central Sweden, using the different soil profiles sampled from the database. Two approaches to calculate effective parameters were tested, in order to obtain generic soil descriptions and examine their ability to represent the average of the variation in chloride and water characteristics obtained for the respective soil type. In general, the use of these effective parameters was successful but overestimations of the water and chloride outflow occurred in the clay, which presented high spatial variability, and of the chloride concentration in the sand, which presented high temporal variability. Overall, the generic soil descriptions were useful in producing reasonable behaviour regarding water and chloride dynamics and could be recommended for general assessments of the environmental impact of non-reactive solutes from areas where simplified soil classifications are available.