A5033145216- Soil Moisture and Remote Sensing
- Soil and Unsaturated Flow
- Geophysical Methods and Applications
- Climate change and permafrost
- Groundwater flow and contamination studies
- Cryospheric studies and observations
- Marine and environmental studies
- Seismic Waves and Analysis
- Landslides and related hazards
- Hydrology and Watershed Management Studies
- Microwave Imaging and Scattering Analysis
- Methane Hydrates and Related Phenomena
- Geology and Paleoclimatology Research
- Arctic and Antarctic ice dynamics
- Plant Water Relations and Carbon Dynamics
- Geophysical and Geoelectrical Methods
- Geological Studies and Exploration
- Landfill Environmental Impact Studies
- Enhanced Oil Recovery Techniques
- Geotechnical and Geomechanical Engineering
- Geothermal Energy Systems and Applications
- Lattice Boltzmann Simulation Studies
- Groundwater and Isotope Geochemistry
- Psychology, Coaching, and Therapy
- Winter Sports Injuries and Performance
Heidelberg University
2012-2021
Rapport (United States)
2021
Groupe SEB
2021
University of Arizona
2021
Heidelberg University
2005-2016
Chinese Academy of Sciences
2008
Paul Scherrer Institute
2006
Institut für Energie- und Umweltforschung Heidelberg
2003-2005
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
2001
University of Hohenheim
1993-1998
Time domain reflectometry (TDR) has been developed to an operational level for the measurement of soil water content during past decade. Because it is able provide fast, precise and nondestructive in situ measurements, become alternative neutron scattering method, particular monitoring under field conditions. One major disadvantages technique that, due relatively high sensitivity signal factors other than content, site‐specific calibration usually required. In this paper a curve TDR method...
Core Ideas A community effort is needed to move soil modeling forward. Establishing an international consortium key in this respect. There a need better integrate existing knowledge models. Integration of data and models challenge modeling. The remarkable complexity its importance wide range ecosystem services presents major challenges the processes. Although progress has occurred last decades, processes remain disjointed between disciplines or services, with considerable uncertainty...
A chloride tracer was applied to the surface of a vegetable field and then leached downward by rainfall irrigation. Tracer concentrations in vertical two‐dimensional region down depth 2.4 m were monitored with suction cups that, installed horizontally from tunnel. The uniformly pulse split into slowly moving main series fast pulses. first pulses reached 2.2 after an infiltration just 31 mm natural rainfall, whereas peak still at 0.84 end experiment 0.853 m. movement can be described...
Effective hydraulic properties of porous media such as the capillary pressure–saturation relation and conductivity function are a direct manifestation underlying pore geometry. The structure macroscopically homogeneous medium (sintered glass) was measured in detail using X‐ray microtomography. We investigated possibility deriving water characteristic on basis analysis. compared three approaches differing amount required input data, effort data processing, their predictive potential. With...
Abstract. Most permafrost is located in the Arctic, where frozen organic carbon makes it an important component of global climate system. Despite fact that Arctic changes more rapidly than rest globe, observational data density region low. Permafrost thaw and release to atmosphere are a positive feedback mechanism can exacerbate warming. This functions via changing land–atmosphere energy mass exchanges. There thus great need understand links between balance, which vary over hourly annual...
The influence of microscopic heterogeneity on flow through a macroscopically homogeneous, variably saturated medium is studied by numerical simulations in two‐dimensional, Miller‐similar medium. As consequence the local there appears complex network channels with interspersed islands low‐flux domains. This hydraulic structure characterized two states which are separated critical point at practically disappears. Transitions between governed degree saturation. complementary that high‐flux...
Abstract. Ponds and lakes are abundant in Arctic permafrost lowlands. They play an important role wetland ecosystems by regulating carbon, water, energy fluxes providing freshwater habitats. However, ponds, i.e., waterbodies with surface areas smaller than 1. 0 × 104 m2, have not been inventoried on global regional scales. The Permafrost Region Pond Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds from modern (2002–2013) high-resolution aerial satellite...
The ground thermal and hydrologic regimes of a site located in the continuous permafrost landscape Taymyr Peninsula, northern Siberia, were studied 1994 1995. aim was to quantify seasonal fluxes water heat active layer from spring thaw fall freeze‐back. Liquid content measured frozen unfrozen soils using time domain reflectometry. present soil at temperatures down −12°C, its volumetric fraction increased with temperature before melting occurred. regime during freeze‐back dominated by latent...
We investigate the use of dielectric spectroscopy to estimate ice content in frozen porous media. A mixing model was used determine volumetric fractions different phases, based on knowledge bulk and single‐phase permittivities. Measurement permittivities at two frequencies with an impedance analyzer is required infer content. One (25 kHz) has be close relaxation frequency ice; other (158 kHz or higher) must well above obtain a permittivity value phase. The theory tested three soil samples...
Summary We investigated the possibility of inferring effective hydraulic properties soil from structure pore space. The aim was to identify structural properties, which are essential for water flow, so that physical experiments may be replaced by direct morphological measurements. in three dimensions serial sections through impregnated samples. complex geometry space quantified terms two characteristics: pore‐size distribution and connectivity. Only pores larger than 0.04 mm were considered....
Numerical simulation of water flow in a two‐dimensional, macroscopically homogeneous, Miller‐similar medium showed the existence network channels with two complementary states separated by critical point [ Roth , 1995]. The consequences this for solute transport are explored numerical simulations using particle tracking. It is found that many experimentally observed features through soil reproduced qualitatively these simulations. Analyzing results reveals corresponding effective travel...
The dynamics of permafrost soils is manifest in the soil temperature which can be measured with high accuracy and temporal resolution. Using continuous data over a period 778 days from mineral hummock field at Bayelva site, Svalbard, we deduce quantify processes constitute dynamics. In particular, conductive heat flux, generation phase transitions, migration water vapor are analyzed. Support for interpretation comes high‐resolution time domain reflectometry measurements liquid content.
Ground-penetrating radar is a fast noninvasive technique that can monitor subsurface structure and water-content distribution. To interpret traveltime information from single common-offset measurements, additional assumptions, such as constant permittivity, usually are required. We present ground-penetrating-radar measurement using multiple transmitter-and-receiver setup to measure simultaneously the reflector depth average soil-water content. It be considered moving minicommon-midpoint...
Arctic lowlands are characterized by large numbers of small waterbodies, which known to affect surface energy budgets and the global carbon cycle. Statistical analysis their size distributions has been hindered shortage observations at sufficiently high spatial resolutions. This situation now changed with high-resolution (< 5m) circum-Arctic Permafrost Region Pond Lake (PeRL) database recently becoming available. We have used this make first consistent, estimation waterbody distributions,...
Summary The food dye Brilliant Blue FCF (Color Index 42090) is often used as tracer in field studies for visualizing the flow pathways of water soils. Batch confirmed findings other researchers that non‐linear sorption important Blue, especially at small concentrations (< 10 g l −1 our soil), and retardation increases with decreasing well increasing ionic strength solutions. Therefore, it not obvious if can be an indicator paths done. In this study, we compared mobility a soil (gleyic...
We apply an energy balance model to the snow cover for snowpack accumulation and ablation at a continuous permafrost site on Spitsbergen snow‐covered periods from fall 1998 winter 2000. The includes net radiative, turbulent, ground, snow, rain heat flux. yields two distinct types of ablation: spring ablation. Energy transferred by sensible input reduces during winter, creating internal ice lenses basal ice. ablates in stages both years. During first stage, surface melt subsequent freezing...
Abstract. Multi-channel ground-penetrating radar (GPR) was applied at a permafrost site on the Tibetan Plateau to investigate influence of surface properties and soil texture late-summer thaw depth average moisture content active layer. Measurements were conducted an approximately 85 × 60 m2 sized area with textural that ranged from medium coarse textured bare finer textured, sparsely vegetated areas covered fine, wind blown sand, it included bed gravel road. The survey allowed clear...
Abstract. Due to the large heterogeneity in hydraulic properties of natural soils, estimation field-scale parameters is difficult. Past research revealed that data from accurate but small-scale laboratory measurements could hardly ever be transferred field scale. In this study, we explore an alternative approach where apparent a layered soil profile are directly estimated inverse modelling time series situ measured water contents obtained domain reflectometry. The covered one-year period...