Parameter estimation by one-step and multi-step outflow experiments for peat soils

The examination of the inverse method for determining the soil moisture retention characteristics and the unsaturated hydraulic conductivity functions was investigated on moorsh and peat soil. Different parameter combinations have been used in the one-step and multi-step outflow procedures for estimating hydraulic properties with the results been compered with standard measurements of moisture retention characteristics (sand table and pressure chambers) and unsaturated hydraulic conductivity measurements using evaporation method. The one-step method yields satisfactory results in moorsh soil for estimation of theta(h) and K(h) functions with the use of cumulative outflow data supplemented in the optimisation procedure with independently measured soil water retention data. The multi-step experiments performed in moorsh soil did not allow accurate prediction of soil water retention characteristic. The K(h) functions estimated from one-step and multi-step experiments in peat soils depends on the parameter vectors used in the optimisation procedure.