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Impact of climate change on recharge and vadose-phreatic storage dynamics of a Mediterranean karst aquifer: Quantitative approach for the management of a complex groundwater resource

dc.contributor.advisorKordilla, Jannes Dr.
dc.contributor.authorBresinsky, Lysander
dc.format.extentXXX Seitende
dc.titleImpact of climate change on recharge and vadose-phreatic storage dynamics of a Mediterranean karst aquifer: Quantitative approach for the management of a complex groundwater resourcede
dc.contributor.refereeSauter, Martin Prof. Dr.
dc.description.abstractengThe Mediterranean basin will be severely affected by global warming and decreased average rainfall and is often portrayed as the most prominent climate change hotspot. At the same time, the Mediterranean basin is endowed with many karst aquifers that are particularly susceptible to droughts due to their hydrogeological characteristics. This thesis addresses the impact of climate change and future groundwater management scenarios on the recharge and storage dynamics of Mediterranean karst water resources using the example of the Western Mountain Aquifer (WMA) in Israel and the West Bank. The main objectives of this thesis are (1) to demonstrate the applicability of variably saturated dual-permeability flow modeling at the catchment scale for the prediction of vadose-phreatic groundwater storage dynamics in karst, (2) the assessment of climate change and groundwater consumption effects and lastly (3) the development of management strategies to mitigate the effects of prolonged droughts. This study employs the finite element, distributed, dual-continuum flow simulator HydroGeoSphere on a high-performance-computing platform. Flow in the variably saturated fractured-porous subsurface is simulated using a dual-permeability approach based on Richards’ equation, assuming that homogenization of microscopic fluid dynamics is valid for both flow domains. We employ the van Genuchten material model to predict the partially saturated permeability but truncate the saturation-permeability relation under dry conditions to maintain a minimum permeability, accounting for gravity-dominated infiltration. This way, the duality of karstic flow, with rapid flow through conduits and slow flow through the rock matrix, can be modeled in both the vadose and phreatic zone. The simulation results highlight the relevance of thick vadose zones in karst aquifers. Vadose storage comprises circa ~45% of the overall dynamic storage in the WMA and has a significant smoothing influence on the temporal characteristics of recharge at the groundwater table of the WMA. Highly variable diurnal precipitation is dampened, and long-term seasonal fluxes become more prominent further from the surface. Subsequently, this thesis employs the presented model to forecast groundwater recharge and storage dynamics under climate change, where two coherent dynamically downscaled high-resolution regional climate projections (daily, 3km, and 8km resolution) until the year 2070 serve as input to the recharge assessment. The model predictions indicate that climate change has a mitigated impact on average recharge because of pathways of preferential infiltration in karst aquifers and the increased intensity of individual rainfall events. However, despite the attenuated decrease of long-term groundwater recharge, the extended meteorological drought periods over several years pose a significant challenge to the consistent freshwater supply from groundwater resources, requiring more resilient management options that generate surpluses in times of increased precipitation input and utilize the aquifer storage during droughts. Lastly, the developed model is employed to assess the storage potential of the WMA for managed aquifer
dc.contributor.coRefereePack, Andreas Prof. Dr.
dc.subject.engClimate Changede
dc.subject.engGroundwater ressourcesde
dc.subject.engGroundwater rechargede
dc.subject.engVadose-Phreatic storage dynamicsde
dc.subject.engDual-Continuum flow modelde
dc.affiliation.instituteFakultät für Geowissenschaften und Geographiede
dc.subject.gokfullHydrologie (PPN613605179)de
dc.notes.confirmationsentConfirmation sent 2023-04-11T11:45:01de

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