Managed Aquifer Recharge (MAR) sites suffer from the long-lasting problem of clogging. The causes of clogging are physical, biological, chemical and mechanical processes and their complex interaction, with physical clogging being recognised as the predominant process. The intrusion and deposition of particles during water recharge affect the hydraulic properties of the infiltration surface, resulting in a decline in the infiltration capacity of the site over the operating years. Cleaning operations are necessary to restore the original infiltration rates. For this purpose, assessing the risk of clogging can determine the site’s vulnerability and improve the scheme’s design. Numerical models are essential to replicate physical clogging processes and predict the decline in infiltration rates. So far, predictive tools for physical clogging assessment have been missing in MAR literature. Hence, the purpose of this study is to analyse and reorganise physical clogging models from applied engineering fields dealing with water infiltration in natural heterogeneous systems. The modelling approaches are illustrated, starting from the main assumptions and conceptualisation of the soil volume and intruding particles. The individual processes are untangled from the multiple studies and reorganised in a systematic comparison of mathematical equations relevant to MAR applications. The numerical models’ predictive power is evaluated for transferability, following limitations and recommendations for a process-based model applicable to surface spreading schemes. Finally, perspectives are given for clogging risk assessment at MAR sites from modelling and site characterisation. The predictive tool could assist decision-makers in planning the MAR site by implementing cost-effective strategies to lower the risk of physical clogging.
Mehr
Maria Chiara Lippera
,
Ulrike Werban
,
Rudy Rossetto
,
Thomas Vienken
Managed aquifer recharge (MAR) techniques are in demand to cope with water scarcity challenges posed by climate change and groundwater overexploitation. One of the long-lasting technical issues associated with MAR systems is physical clogging. The intrusion and deposition of external fines during water recharge reduce the infiltration capacity of the site over time. Operation and maintenance (O&M) costs are experienced directly at the site to restore the original efficiency of infiltration rates. Thus, investors need reliable estimations of the risk of clogging during the planning of the site. As a rule, in MAR design, the main parameter of concern for physical clogging is the total suspended solids (TSS), and most clogging models rely on experiment calibrations in 1D sand columns. However, secondary processes can control the development and spatial distribution of physical clogging in field conditions. The proposed work aims to detect key clogging factors directly in the field and to model these processes for reproducibility at other sites. The fieldwork is conducted at the two-stage infiltration basin in Suvereto (Tuscany, Italy). Spatial factors are included in the analysis (i.e. basin topography) to explain clogging patterns in the field altered by erosion processes. The observed clogging profiles at two sampled locations exhibiting clogging are replicated by a mathematical model. Based on the computation of annual erosion rates in the pond and fines’ redistribution, the exceeding fines’ contents over depth are validated with an RMSE of 2.53% and 12.53%. The infiltration capacity of the site is estimated to reach a stable value of 90% of the initial infiltration capacity over 20 years, given the Suvereto basin features. The model's parameterisation from field measurements represents a great advantage over existing clogging models due to its transferability to other MAR sites. The assessment of the risk of clogging supported by field characterization and numerical modelling is cost-effective and assists the deduction of O&M schemes for MAR sites.
Mehr
Georg Kaufmann
,
Douchko Romanov
,
Ulrike Werban
,
Thomas Vienken
Since 2004, collapse sinkholes occur on the sports field of Münsterdorf, a village north of Hamburg in Germany. The sinkholes, around 2–5 m in diameter and 3–5 m deep, develop in peri-glacial sand, which in around 20 m depth is underlain by cretaceous chalk. The chalk has been pushed up close to the surface by a salt diapir. The sinkhole formation initiated suddenly and occurs with a frequency of one every two years. We use a variety of geophysical results (e.g. gravity, electrical resistivity imaging, ground-penetrating radar) from previous field-work campaigns together with a new data set from direct-push based methods to infer mechanical and hydrological properties of the material beneath the sports field (peri-glacial sand, glacial marl, cretaceous chalk). Based on the derived material properties, we develop a mechanical model for the sinkhole collapse, starting from simple analytical considerations and then moving towards a three-dimensional distinct-element model explaining the sudden onset of collapse sinkholes for the sports field. The mechanical model supports our hypothesis that the sudden onset of sinkholes is triggered by changes in groundwater level.
Mehr
Nele Grünenbaum
,
Thomas Günther
,
Janek Greskowiak
,
Thomas Vienken
,
Mike Müller-Petke
,
Gudrun Massmann
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
,
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
,
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
,
Thomas Vienken
,
Frank Wuttke
,
Christof Beyer
Monitoring the impact of intensive shallow geothermal energy use on groundwater temperatures in a residential neighborhood (2019) Geothermal Energy 7 , S. 8.
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
,
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
,
Thomas Vienken
,
Ulrike Werban
,
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.
Boyan Meng
,
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
Thomas Vienken
,
Katrin Matthes
,
Hagen Nusche
,
Peter Dietrich
Reply to the Commentary by Fuchs et al. on the Paper „Effects of Measuring Uncertainties in Particle Size Analysis on the Calculation of Transmittance Levels“ by Matthes et al (2013) Grundwasser 17 (2), S. 105-111.
Einzigartiges Kompendium für die Planung oberflächennaher geothermischer SystemeKombination von experimenteller Arbeit und ComputersimulationDatenbank, die experimentelle Daten und numerische Simulationen kombiniertVirtuelle Realität als Werkzeug zur Daten- und Modellanalyse
Managed aquifer recharge (MAR) is an emerging solution to effectively replenish overused groundwater resources, but high associated costs often hinder its uptake. There are several parameters to consider when determining the cost of MAR, including recharge types, scale of MAR schemes, land acquisition, operation and maintenance period, and the hydrogeological setting. Hydraulic conductivity and its spatial variability are the most significant hydrogeological parameters for predicting infiltration rates at MAR sites, but limited data availability makes accurate predictions often challenging. Hence, it is essential to increase data availability to optimize MAR efficiency and to better assess its economic performance. Therefore, a novel approach for MAR planning is presented in this article to efficiently enhance the data availability during the conceptual stage of MAR planning by combining site exploration, spatially resolved infiltration rate estimation, and cost analysis. The approach was applied at an actual MAR site in Vincenza, Italy, and incorporated an electromagnetic induction survey and direct push profiling as across-scale investigation methods to enhance site delineation and subsequent parameterization of the identified zones using laboratory analysis of collected samples. This MAR site is particularly suitable for its heterogeneous subsurface structure and potential to counteract groundwater depletion. The performed investigation resulted in an image of the lateral variation of subsurface conditions and allowed the delineation of three zones with different infiltration behavior, with 99.5% of infiltration occurring in just two zones, representing only 22.1% of the site. In this particular scenario, the overall cost per cubic meter of recharged water can be reduced by 59.1% by identifying and eliminating unfavorable zones. This study provides scientists and practitioners with a useful tool for MAR planning that can be applied to a wide range of sites with complex geology, thereby reducing water costs, minimizing the environmental impact of infrastructure construction, and reducing land use conflicts.
Mehr
Anke Bucher
,
Uwe-Jens Görke
,
Rüdiger Grimm
,
Nele Hastreiter
,
Olaf Kolditz
,
Katrin Lubashevsky
,
Jakob Randow
,
Karsten Rink
,
Simon Richter
,
Stephan Schönfelder
,
Haibing Shao
,
Thomas Vienken
,
Konstanze Zschoke
Im Jahre 2015 wohnten etwa 75 % der deutschen Bevölkerung in Städten (Statista 2018). Entsprechend dem Ziel des Energiekonzepts der Bundesregierung (Bundesregierung 2018), den Gebäudebestandteil bis 2050 nahezu klimaneutral zu gestalten, spielen städtische Quartiere eine herausragende Rolle bei der Steigerung von Energieeffizienz und somit der Senkung von Schadstoffemissionen. Laut Angaben des Umweltbundesamtes betrug der Anteil von Wärme/Kälte im Jahr 2012 knapp 51 % am Endenergieverbrauch in Deutschland. In privaten Haushalten ist der thermische Anteil mit bis zu 80 % gemessen am Verbrauch von Endenergie noch deutlich größer. Davon stammten 2016 lediglich 13,4 % aus erneuerbaren Quellen (Bundesministerium für Wirtschaft und Klimaschutz 2022), mit einem seit 2012 nahezu stagnierenden Anteil. Diese Zahlen verdeutlichen das große Effizienzpotenzial von Stadtquartieren im Wärmesektor und deren Schlüsselrolle im Prozess der Energiewende.
Mehr
Steve Henker
,
Nele Hastreiter
,
Jakob Randow
,
Karsten Rink
,
Paul Satke
,
Thomas Vienken
Für die im Verbundprojekt Energieeffiziente Auslegung und Planung dezentraler Versorgungsnetze zum Heizen und Kühlen von Stadtquartieren unter Nutzung des oberflächennahen geologischen Raumes (EASyQuart) durchgeführten Untersuchungen, Validierungen und Realmessungen wurden eine Reihe von Standorten und -modellen verwendet. Mit der Einschränkung, dass kein einheitliches Gesamtmodell für die Durchführung aller Vorhaben an einem Standort zur Verfügung stand, wurden für die jeweiligen Anwendungsfälle spezifische Bezugspunkte genutzt.
Mehr
Nele Hastreiter
,
Steve Henker
,
Marco Pohle
,
Ulrike Werban
,
Thomas Vienken
Im Rahmen des Projektes Energieeffiziente Auslegung und Planung dezentraler Versorgungsnetze zum Heizen und Kühlen von Stadtquartieren unter Nutzung des oberflächennahen geologischen Raumes (EASyQuart) wurden die Anforderungen an die Erkundung und das Monitoring untersucht, die aus der geothermischen Erschließung auf Wohngebietsskala hervorgehen. Diese besonderen Anforderungen entstehen aus der räumlichen Dimension der Untersuchungsgebiete sowie aus der hohen geothermischen Nutzungsdichte bei Quartieren.
Mehr
Jakob Randow
,
Anke Bucher
,
Uwe-Jens Görke
,
Rüdiger Grimm
,
Nele Hastreiter
,
Olaf Kolditz
,
Katrin Lubashevsky
,
Simon Richter
,
Karsten Rink
,
Stephan Schönfelder
,
Haibing Shao
,
Thomas Vienken
,
Konstanze Zschoke
Ein wesentlicher Teil des Innovationsgehalts von EASyQuart besteht darin, offene wissenschaftliche Fragestellungen bei der Optimierung großflächiger oberflächennaher Geothermienetzwerke klären zu helfen (z. B. durch Anpassung, Entwicklung und Bewertung standort- und prozessbezogener Erkundungs- und Monitoringverfahren, Sensitivitätsstudien, numerische Unsicherheitsanalysen sowie gekoppelte Simulationen des Gesamtsystems Untergrund-Haustechnik). Zudem wurden exemplarisch konkrete Prognoseinstrumentarien zur standortbasierten Analyse der Versorgungs- und Bedarfsseite für verschiedene Arbeitsschritte eines Auslegungs- und Planungsprozesses oberflächennaher geothermischer Anlagen zum Heizen und Kühlen erstellt und mit Daten realer Standorte validiert. Auf dieser Basis konnten vom Verbundvorhaben Empfehlungen für die Flexibilisierung von Auslegungsverfahren und regulativen Rahmenbedingungen für Errichtung und Betrieb der betrachteten Systeme formuliert werden.
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