Forschungszentrum Landschaftsentwicklung und Bergbaulandschaften (FZLB)
Refine
Year of publication
Document Type
Keywords
- deep soil loosening (1)
- lignite mine (1)
Institute
BTU
Multidimensional visualization of preferential flow pathways using neutron and x-ray radiation
(2017)
An artificial catchment was constructed to study initial soil and ecosystem development. Our research site is the hydrologic catchment area “Chicken Creek”, 20 km south of the city Cottbus (Germany), which is left to undirected succession. The approximately 6-ha catchment area was built in 2005 of coarse-textured quaternary sediments and forms a back- and foot-slope that flattens out to a pond. A clay liner, 2-3 m in thickness, seals the catchment at the bottom. The initial “soil” layer consists of sandy quaternary sediments, approximately 2–3 m in thickness, that overlay the clay liner. The sediments of the artificial system are in the very initial stage of soil formation. As a key process, the pore structure dynamics in the soil at the surface strongly influences erosion, infiltration, matter dynamics, and vegetation establishment. Little is known, however, about early macropore formation. This presentation focuses on observations of the general development of the catchment, with emphasis on soil structure modifications, such as soil surface crusts, structure formation from ground beetles, moss vegetation and its effect on water flow.
We visualized the soil structure and flow patterns using a combination of neutron radiography, neutron tomography (NT) and X-ray computed tomography (CT) experiments. All 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 containing heterogeneities of different origin. Our observations demonstrate relatively high abiotic and biotic dynamics of soil pore structure in the soil surface even during the very early development stages of the catchment. The structure formation influences runoff and infiltration by forming sealing layers or preferential flow paths, due to biotic activity.
Ecosystems are characterized by high complexity and are dynamically changing by abiotic and biotic drivers such as climate, vegetation and soil fauna. Due to feedback processes between compartments, ecosystems show an inherent degree of locally heterogeneous properties and structures at multiple spatial and temporal scales.
The constructed catchment “Chicken Creek” represents a unique and outstanding site to study an ecosystem at the initial stage of development. The catchment is located about 20 km south of the city of Cottbus (Germany). The 6-ha catchment area was built in 2005 of coarse-textured quaternary sediments from the adjacent lignite mine and forms a back- and foot-slope that flattens out to a pond. A clay liner of 2-3 m thickness seals the catchment at the bottom, allowing for the formation of a local water body fed by precipitation. After construction the site was left to an unrestricted and unmanaged succession to elucidate the role of structures und processes during the initial establishment of an ecosystem. To study processes of ecosystem development and newly emerging structures the Chicken Creek catchment is equipped with a comprehensive ecological monitoring network. A network of more than 40 wells and two weirs allow for recording groundwater levels, surface runoff and discharge. Meteorological parameters are recorded at three weather stations. Annual aerial photos and vegetation monitoring reveal the floral colonisation of the area. Here, we present the 12 years of diverse and extensive monitoring program which has been launched to measure hydrological, biological, meteorological, and pedological parameters during the ecological development of the catchment area.