Landesamt fur Geologie

Freiburg, Germany

Landesamt fur Geologie

Freiburg, Germany
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Upper Jurassic karstified limestones in southern Germany are characterized by a dual-porosity system. Here we present a new model that describes the basic processes from recharge to discharge. While recharge is distributed to both main conduits and fractures, only minor amounts of the total runoff reach the karst system directly (direct runoff) while most water infiltrates into the fractured matrix. This mechanism expels pre-event water from the fissured matrix and into karst conduits. Additionally, matrix storage exponentially decreases during baseflow conditions. Altogether, direct runoff, pre-event water and baseflow fill the karst system and make up the spring discharge. Based on a time series of 40 years of recharge data, the model simulates daily changes of groundwater volumes within the two storage systems. Prerequisites are recession coefficients for baseflow and conduits. A distribution coefficient calculates the amount of direct runoff and a second coefficient the amount of pre-event water. Calculated discharges were in good agreement with the spring hydrograph. © 2013 Springer-Verlag Berlin Heidelberg.

Haggag M.A.,Ain Shams University | Strougo A.,Ain Shams University | Luterbacher H.,Museo Geologico Del Seminario de Barcelona | Wielandt U.,Landesamt fur Geologie
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2010

During the Paleocene and Early Eocene, three main events affected the stratigraphie distribution of the planktic foraminifera in the area of the Farafra Oasis. The first one at the K/Pg boundary is characterized by a stratigraphie gap corresponding to most of the lower Paleocene. The second event starts in the upper part of the Praemurica uncinata Zone (P2) and extends into the Globanomalina pseudomenardii Zone (P4a). It is marked again by a stratigraphie gap corresponding to most of the Middle Paleocene or to numerous short diastems. The third event is the widespread "velascoensis- event". All three events are also reflected by the intensive reworking of older faunas. © 2010 Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

Becker A.,Ingenieurburo fur Bauwesen | Leinenbach J.,Geopartner S.a R.l | Rogall M.,Landesamt fur Geologie | Schiffel J.,Spezialtiefbau GmbH | Stolben F.,Stolben GmbH
Mainzer Geowissenschaftliche Mitteilungen | Year: 2010

In April 2008, massive cracks and damages at a road in the vineyards of the city of Zell in the Moselle valley indicated the collapse of an 8 m high retaining wall of the local cemetery. Due to the fact that the road is a major traffic route when the city is flooded by the Moselle river, a stabilization and remediation of the wall and the road was inevitable. The complex geotechnical and morphological situation required a solution that met the safety requirements as well as the preservation of the historic buildings. Finally, the old retaining wall was successfully stabilized, using rock bolts and shot crete.

Reh R.,University of Gottingen | Hillebrand O.,University of Gottingen | Geyer T.,Landesamt fur Geologie | Nodler K.,University of Gottingen | And 2 more authors.
Grundwasser | Year: 2014

In the presented work the occurrence of organic micro-pollutants is discussed for two karst areas with different geological characteristics and land-use patterns.Within an urban moderately karstified catchment with a large number of local input sources (e.g. contaminated sites, sewer leakages), a greater variety of micro-pollutants is found compared to a rural area. Mostly the concentrations of these compounds decrease below quantification limits before emerging at the spring and can therefore only be detected by a comprehensive network of sampling points. Springs show the presence of micro-pollutants, either recently applied in large amounts or characterized by high persistence.At the outlet of a highly karstified and consequently highly permeable aquifer readily biodegradable compounds are detected. Due to high groundwater flow velocities investigations of micro-pollutants require a highly resolved monitoring.Therefore, beside substance properties, also hydrogeological characteristics affect the spectrum of detectable micro-pollutants. © 2014, Springer-Verlag Berlin Heidelberg.

Investigations of a 30-m-high section of Pleistocene sediments at Illmensee-Lichtenegg, Höchsten in Baden-Württemberg provide detailed information on subglacial conditions beneath the Rhine Glacier outlet of the Alpine ice sheet in southern Germany. The sediment exposure extends from an upper cemented sand and gravel (Deckenschotter) into diamictic units that extend down to weathered Molasse bedrock. The exposure reveals sediments symptomatic of active syndepositional stress/strain processes ongoing beneath the ice sheet. Macrosedimentology reveals diamicton subfacies units and a strong uni-direction of ice motion based on clast fabric analyses. At the microscale level, thin-section analyses provide a substantially clearer picture of the dynamics of subglacial sediment deformation and till emplacement. Evidence based on detailed micromorphological analyses reveals microstructural strain and depositional markers that indicate a subglacial environment of ongoing soft bed deformation in which the diamictons can be readily identified as subglacial tills. Within this subglacial environment, distinct changes in pore-water pressure and sediment rheology can be detected. These changes reveal fluctuating conditions of progressive, non-pervasive deformation associated with rapid changes in effective stress and shear strain leading to till emplacement. This site, through the application of micromorphology, increases our understanding of localized subglacial conditions and till formation. © 2010 The Authors. Boreas © 2010 The Boreas Collegium.

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