Die chronologische Liste zeigt aktuelle Veröffentlichungen aus dem Forschungsbetrieb der Hochschule Weihenstephan-Triesdorf. Zuständig ist das Zentrum für Forschung und Wissenstransfer (ZFW).
Understanding the interaction of terrestrial freshwater and seawater in the subterranean estuary (STE) is an important factor when considering nutrient fluxes from land to sea. State-of-the-art research describes the STE by a tide-induced upper saline recirculation cell, a freshwater discharge tube and a deep saltwater wedge. However, recent numerical modelling and shallow hydrogeochemical investigations for high-energy beaches indicate that multiple saline recirculation cells may exist and affect the land-sea interaction. Electrical Resistivity Tomography (ERT) and Direct Push (DP) technologies are common tools to explore the subsurface. Due to their sensitivity to the electrical conductivity of pore water, they permit investigating the STE. This study combines ERT and DP to image the salinity distribution within the STE of a meso-tidal, high-energy beach. We actively incorporate the DP data into the ERT inversion and use geostatistical regularization for closing the resolution gap. For the first time, our experimental results confirm the existence of several 10–20 m deep reaching upper saline recirculation cells and corresponding brackish discharge locations generated by a pronounced runnel-ridge beach system in 2019, whereas in 2021 only a single cell was displayed for a flat topography at the time.
Mehr
Maria Chiara Lippera,
Ulrike Werban,
Prof. Dr. Thomas Vienken
Managed aquifer recharge (MAR) is an emerging approach to enhancing water storage capacity, improving water supply security and countering groundwater overexploitation. However, physical clogging, i.e. accumulation of suspended organic and inorganic solids within a sediment matrix, can lead to a significant reduction of infiltration rates and present difficulties in the functioning of MAR infrastructure. Clogging and subsequent reduction in infiltration capacity are often quantified based on monitoring data or field investigations, rather than on forecasts. Existing predictive models require specific parameterisation, making an application to heterogeneous sites, or under changing conditions, difficult. Hence, a generalised understanding of how intrusive fine particles distribute over depth during water recharge cycles for typical MAR infiltration basin sediments is needed to predict clogging susceptibility and clogging patterns already in the planning phase and before operation of MAR schemes. The study will contribute to operational reliability, deduce optimised management practices, and, ideally, reduce maintenance efforts. To achieve this goal, data from different soil-column clogging experiments are reviewed and complemented with experiments to establish a generally valid relationship for the vertical distribution of intrusive fines under consideration of the primary porous media’s and intruding particles’ characteristics. Obtained results allow for quantification of the amount of particles retained at the surface of the porous media, i.e. formation of a filter cake, a description of the distribution of fines over depth, and total clogging depth. Finally, the findings are applied to a real MAR case study site to showcase the quantification of clogging effects on recharge rates.
Mehr
Rudy Rossetto,
Alessio Barbagli,
Giovanna De Filippis,
Chiara Marchina,
Prof. Dr. Thomas Vienken,
Giorgio Mazzanti
Johannes Nordbeck,
Sebastian Bauer,
Andreas Dahmke,
Jens-Olaf Delfs,
Hugo Gomes,
Henok Hailemariam,
Constantin Kinias,
Kerstin Meier zu Beerentrup,
Thomas Nagel,
Christian Smirr,
Prof. Dr. Thomas Vienken,
Frank Wuttke,
Christof Beyer
Prof. Dr. Thomas Vienken,
Manuel Kreck,
Prof. Dr. Peter Dietrich
Berechtigungen: Open Access
Berechtigungen: Peer Reviewed
Monitoring the impact of intensive shallow geothermal energy use on groundwater temperatures in a residential neighborhood (2019) Geothermal Energy 7 .
DOI: 10.1186/s40517-019-0123-x
The use of shallow geothermal energy increasingly receives attention as a suitable alternative to fossil fuel-based space heating and cooling, warm water provision, as well as for seasonal heat storage throughout Europe. With the advent of shallow geothermal energy use on large scales, a vivid discussion of potential ecological and economic impacts has arisen but actual field data are scarce. An intensive groundwater temperature-monitoring program over a period of 3 years with consecutive measurements was, therefore, initiated at a residential neighborhood in the city of Cologne, Germany, under intense shallow geothermal use. The aim of the monitoring program was to overcome the existing data scarcity by pinpointing the effects of the intensive thermal use of the subsurface on groundwater temperatures and to foster understanding of urban groundwater temperature evolution. Results show that even though energy demands of the individual houses and energy extraction rates of the shallow geothermal systems were comparably small in this case, the accumulation of shallow geothermal users had a measurable impact on overall groundwater temperatures.
Boyan Meng,
Prof. Dr. Thomas Vienken,
Olaf Kolditz,
Haibing Shao
Evaluating the thermal impacts and sustainability of intensive shallow geothermal utilization on a neighborhood scale: Lessons learned from a case study (2019) Energy Conversion and Management 2019 (199).
DOI: 10.1016/j.enconman.2019.111913
Boyan Meng,
Prof. Dr. Thomas Vienken,
Olaf Kolditz,
Haibing Shao
Ground source heat pump (GSHP) systems have been considered to be a low-carbon technology to provide heating and cooling for buildings in urban environments. This study focuses on the short-and long-term evolution of groundwater temperature induced by high-density GSHP installations in an urban residential area in Cologne, Germany. Specifically, a 2D heat transport model considering both thermal convection and conduction has been constructed using the finite element simulator OpenGeoSys. The simulated temperature changes within the initial few years were compared to the monitored dataset, while the GSHP heating load and thermal conductivity were calibrated. Subsequently, the validated model was run for 25 years to evaluate the long-term trend of the subsurface temperature. Also, effects of model uncertainties were explored with different simulated scenarios. Results indicate that sufficiently large groundwater flow and a high cooling ratio can effectively mitigate ground cooling. Based on these findings, best and worst-case scenarios were formulated for the studied case and the sustainability of GSHP operation were evaluated accordingly. As an outcome, specific design and operation criteria were proposed for the sustainable utilization of shallow geothermal energy for the heating and cooling of buildings in urban areas.
Mehr
Georg Kaufmann,
Douchko Romanov,
Thomas Tippelt,
Prof. Dr. Thomas Vienken,
Ulrike Werban,
Prof. Dr. Peter Dietrich,
Franziska Mai,
Frank Börner
Münsterdorf is a small village in the north of Hamburg, located along the northern rim of a salt diapir. The Permian rocks are uplifted and overlying rocks such as the Cretaceous limestone, normally at several kilometers depth, have been pushed close to the surface. In Münsterdorf, the Cretaceous limestone can be found at around 20 m depth, and about 2 km further south, Cretaceous limestones are quarried in a large open-pit mine.Since 2004, collapse sinkholes have formed on a sports field in Münsterdorf, with a frequency of about 1 every two years, about 3–5 m in diameter and 3–5 m deep. The collapse sinkholes do not reach the underlying limestone, but seem to be related to accelerated dissolution in that formation. Above the Cretaceous limestone, Quaternary gravels and glacial tills provide a non-soluble, but permeable and heterogeneous cover of about 20 m thickness.We have mapped the sports field and its vicinity with gravity (GRAV), electrical resistivity imaging (ERI), and ground-penetrating radar (GPR). The ERI profiles indicate a significant change in the surface layer, from thin and irregular in the northern part to thicker and more homogeneous in the southern part of the sports field. GPR profiles confirm this result.We numerically model the evolution of flow and porosity in the Cretaceous limestone to estimate the evolution time of subsurface voids in the limestone, and we discuss the potential cause of the sinkhole formation and its sudden onset in light of the hydraulic boundary conditions.
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