Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 9 2009 10.5194/hess-13-1671-2009 http://www.hydrol-earth-syst-sci.net/13/1671/2009/ http://www.hydrol-earth-syst-sci.net/13/1671/2009/hess-13-1671-2009.html http://www.hydrol-earth-syst-sci.net/13/1671/2009/hess-13-1671-2009.pdf 1671 1683 2009-09-18 Large zero-tension plate lysimeters for soil water and solute collection in undisturbed soils A. Peters andre.peters@tu-berlin.de W. Durner Institut für Geoökologie, Technische Universität Braunschweig, Braunschweig, Germany now at: Institut für Ökologie, Technische Universität Berlin, Berlin, Germany Water collection from undisturbed unsaturated soils to estimate in situ water and solute fluxes in the field is a challenge, in particular if soils are heterogeneous. Large sampling devices are required if preferential flow paths are present. We present a modular plate system that allows installation of large zero-tension lysimeter plates under undisturbed soils in the field. To investigate the influence of the lysimeter on the water flow field in the soil, a numerical 2-D simulation study was conducted for homogeneous soils with uni- and bimodal pore-size distributions and stochastic Miller-Miller heterogeneity. The collection efficiency was found to be highly dependent on the hydraulic functions, infiltration rate, and lysimeter size, and was furthermore affected by the degree of heterogeneity. In homogeneous soils with high saturated conductivities the devices perform poorly and even large lysimeters (width 250 cm) can be bypassed by the soil water. Heterogeneities of soil hydraulic properties result into a network of flow channels that enhance the sampling efficiency of the lysimeter plates. 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