Ptak-Fix, Thomas

[["dc.bibliographiccitation.firstpage","107"],["dc.bibliographiccitation.journal","Journal of contaminant hydrology"],["dc.bibliographiccitation.lastpage","121"],["dc.bibliographiccitation.volume","177-178"],["dc.contributor.author","Yang, Jie"],["dc.contributor.author","Graf, Thomas"],["dc.contributor.author","Ptak, Thomas"],["dc.date.accessioned","2018-06-28T09:30:59Z"],["dc.date.available","2018-06-28T09:30:59Z"],["dc.date.issued","2015"],["dc.description.abstract","Climate change is expected to induce sea level rise in the German Bight, which is part of the North Sea, Germany. Climate change may also modify river discharge of the river Weser flowing into the German Bight, which will alter both pressure and salinity distributions in the river Weser estuary. To study the long-term interaction between sea level rise, discharge variations, a storm surge and coastal aquifer flow dynamics, a 3D seawater intrusion model was designed using the fully coupled surface-subsurface numerical model HydroGeoSphere. The model simulates the coastal aquifer as an integral system considering complexities such as variable-density flow, variably saturated flow, irregular boundary conditions, irregular land surface and anthropogenic structures (e.g., dyke, drainage canals, water gates). The simulated steady-state groundwater flow of the year 2009 is calibrated using PEST. In addition, four climate change scenarios are simulated based on the calibrated model: (i) sea level rise of 1m, (ii) the salinity of the seaside boundary increases by 4 PSU (Practical Salinity Units), (iii) the salinity of the seaside boundary decreases by 12 PSU, and (iv) a storm surge with partial dyke failure. Under scenarios (i) and (iv), the salinized area expands several kilometers further inland during several years. Natural remediation can take up to 20 years. However, sudden short-term salinity changes in the river Weser estuary do not influence the salinized area in the coastal aquifer. The obtained results are useful for coastal engineering practices and drinking water resource management."],["dc.identifier.doi","10.1016/j.jconhyd.2015.03.014"],["dc.identifier.pmid","25889797"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15157"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.eissn","1873-6009"],["dc.title","Impact of climate change on freshwater resources in a heterogeneous coastal aquifer of Bremerhaven, Germany: A three-dimensional modeling study"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2695"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Hydrogeology Journal"],["dc.bibliographiccitation.lastpage","2705"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Yang, Jie"],["dc.contributor.author","Graf, Thomas"],["dc.contributor.author","Ptak, Thomas"],["dc.date.accessioned","2020-04-02T13:12:08Z"],["dc.date.available","2020-04-02T13:12:08Z"],["dc.date.issued","2019"],["dc.identifier.doi","10.1007/s10040-019-02009-9"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/63533"],["dc.relation.issn","1431-2174"],["dc.relation.issn","1435-0157"],["dc.title","Combined influence of weir construction and sea-level rise on freshwater resources of a coastal aquifer in northern Germany"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","39"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Grundwasser"],["dc.bibliographiccitation.lastpage","51"],["dc.bibliographiccitation.volume","20"],["dc.contributor.author","Yang, J."],["dc.contributor.author","Graf, Thomas"],["dc.contributor.author","Ptak, Thomas"],["dc.date.accessioned","2018-11-07T10:00:16Z"],["dc.date.available","2018-11-07T10:00:16Z"],["dc.date.issued","2015"],["dc.description.abstract","Climate change will affect coastal groundwater resources due to the mean sea level rise (MSLR) and an increase in storm intensity and frequency. Increasing saltwater intrusion from the subsurface as well as intrusion into aquifers from land-surface storm surges can be expected. We numerically investigate the impacts of MSLR and storm surge events in a 2D cross-sectional aquifer at the North-German coast using the coupled surface-subsurface approach of the HydroGeoSphere model. Aquifer heterogeneity is considered to investigate the influence of heterogeneity on the migration of salt plumes in the aquifer. A 1 m MSLR causes the saltwater/freshwater interface to migrate up to 1250 m landward, and the salinized area of the aquifer to expand up to 2050 m landward. Results from a storm surge simulation show that salt plume fingers develop below the flooded land surface, however, the fate of the salt plumes is highly dependent on the hydraulic conductivity of the subsurface."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [GR 3463/2-1]"],["dc.identifier.doi","10.1007/s00767-014-0279-z"],["dc.identifier.isi","000351399600005"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37766"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.publisher.place","Heidelberg"],["dc.relation.issn","1432-1165"],["dc.relation.issn","1430-483X"],["dc.title","Sea level rise and storm surge effects in a coastal heterogeneous aquifer: a 2D modelling study in northern Germany"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","61"],["dc.bibliographiccitation.journal","Journal of Contaminant Hydrology"],["dc.bibliographiccitation.lastpage","75"],["dc.bibliographiccitation.volume","149"],["dc.contributor.author","Yang, J."],["dc.contributor.author","Graf, Thomas"],["dc.contributor.author","Herold, Maria"],["dc.contributor.author","Ptak, Thomas"],["dc.date.accessioned","2018-11-07T09:24:16Z"],["dc.date.available","2018-11-07T09:24:16Z"],["dc.date.issued","2013"],["dc.description.abstract","Coastal aquifers are complex hydrologic systems because many physical processes interact: (i) variably saturated flow, (ii) spatial-temporal fluid density variations, (iii) tidal fluctuations, (iv) storm surges overtopping dykes, and (v) surface runoff of storm water. The HydroGeoSphere model is used to numerically simulate coastal flow dynamics, assuming a fully coupled surface-subsurface approach, accounting for all processes listed above. The diffusive wave approximation of the St. Venant equation is used to describe surface flow. Surface flow and salt transport are fully coupled with subsurficial variably saturated, variable-density flow and salt transport through mathematical terms that represent exchange of fluid mass and solute mass, respectively. Tides and storm surges induce a time-variant head that is applied to nodes of the surface domain. The approach is applied to real cases of tide and storm surge events. Tide simulation results confirm the existence of a recirculating zone, forming beneath the upper part of the intertidal zone. By monitoring the exchange fluid flux rates through the beach, it was found that the major inflow to the aquifer takes place at the upper part of the intertidal zone, which explains the formation of the recirculating zone. The recirculating zone is forming particularly during rising tide. Results from a storm surge simulation show that plume fingers develop below the flooded land surface. Natural remediation by seaward flowing freshwater is relatively slow, such that reducing the salt concentration in the aquifer down to drinking water standards takes up to 10 years. (C) 2013 Elsevier B.V. All rights reserved."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [GR 3463/2-1]"],["dc.identifier.doi","10.1016/j.jconhyd.2013.03.002"],["dc.identifier.isi","000319550400005"],["dc.identifier.pmid","23603354"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29784"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","1873-6009"],["dc.relation.issn","0169-7722"],["dc.title","Modelling the effects of tides and storm surges on coastal aquifers using a coupled surface-subsurface approach"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]