Novel lysimeter techniques - a basis for the improved investigation of water, gas, and solute transport in soils

For many years lysimeters have been proven to be effective tools in assessi ng and predicting the effects of current land use and future land use chang es in catchment areas on both water and solute balances. Although due to th e diverse aspects of mass transport modelling, many different types of lysi meters exist, water and solute balances are by no means fully understood, e specially in post-mining areas. To tackle this problem, a new piece of equi pment has been developed which enables the actual weight of a lysimeter to be precisely measured. The newly designed device, which has been used for o ne of the experiments described in this paper, permits the weighing of for example a 2 m(3) lysimeter vessel with an accuracy down to 30 g. The second newly developed appliance presented here is the GAMS (Gas-Migration-Simula tor). Basically comparable to a lysimeter, the difference is that the GAMS allows the detailed investigation of soil-gas migration processes and their dependence on parameters like the diffusion coefficient and the gas permea bility of the soil, alterations of the groundwater level and on various ext ernal influences such as changes of the actual meteorological conditions. T hese two newly developed techniques are described in this paper, acid their respective suitability is demonstrated on the basis of data sets recorded during initial experiments.