@phdthesis{Badorreck2016, author = {Badorreck, Annika}, title = {Multidimensional visualization of preferential flow pathways using neutron and x-ray radiation}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-41615}, school = {BTU Cottbus - Senftenberg}, year = {2016}, abstract = {The occurrence of preferential flow of water in soils is rather the rule than the exception particularly in heterogeneous structured soils. The quantitative prediction is difficult because of the spatial as well as temporal variability. One aim of the dissertation was to visualize the soil structure and flow patterns in mine soils using a combination of neutron radiography, neutron tomography and x-ray computed tomography experiments. Both radiation techniques were used to describe preferential pathways as a soil structure with CT and the process of preferential flow of water with NT. For the first time neutron radiation was applied on undisturbed soil cores to visualize water distributions in natural soils on three examples for heterogeneities of different origin. In a first investigation we used neutron radiography to analyze the moisture distribution in undisturbed slab-type and cylindrical samples of mine soils containing lignitic fragments and inclined soil layers. 2D radiography sequences indicated that flow pathways are highly dependent on the shape, distribution, and internal structure of the lignitic fragments. For 3D experiments, the quantitative analysis of water contents failed due to a pronounced beam hardening effect. The tensiometer data indicated the existence of local non-equilibrium in pressure heads between fragments and matric pore regions. The objective of the second study was to analyze and visualize the effects of initial soil structure formation at the surface of bare soils in an artificial hydrological catchment that has been left to undirected ecological succession for three years. The three-dimensional (3D) micro-morphology was described using the X-ray computed tomography (CT); two-dimensional (2D) infiltration patterns were obtained from drip infiltration experiments using time-resolved neutron radiography (NT). The analyses of CT data indicate the existence of (i) structural crusts on soil consisting of sandy to loamy sediments and (ii) depositional crusts on sandy sediments. The results of combined observations using CT and NT suggest that the initial soil surface structure alterations of young sandy sediment modify moisture patterns of infiltrating water only slightly. The aim of the 3rd experiment was to study effect of two 'ecological engineers', moss vegetation and beetle larvae on pore structure and infiltration. The soil pore structure was characterized by micro-computed tomography analyses of bare soil, sparse and dense moss-vegetated samples containing a single burrow. Flow patterns of infiltration experiments were visualized using the neutron radiography technique. The results of this study suggest that moss vegetation and burrowing activity of ground beetles strongly control the initial soil development by modification of pore structure and surface water infiltration.}, subject = {Water; Soil; Preferential flow; Computed tomography; Neutron radiography; Wasser; Boden; Pr{\"a}ferentielle Fließwege; Computertomografie; Neutronenradiografie; Bodengef{\"u}ge; Wasser; Fließverhalten}, language = {en} }