Impacts of predicted climate change on groundwater flow systems: Can wetlands disappear due to recharge reduction?

Climate change can directly influence groundwater systems through modification of recharge. Affecting not only groundwater levels and flow dynamics, climate change can also modify the fragmentation and hierarchy of groundwater flow systems. In this study, the influence of climate change - impacted recharge on groundwater levels and on inter-connected groundwater flow patterns is evaluated. Special emphasis is placed on how flow system hierarchy may change, to examine possible consequences on groundwater-related shallow surface water bodies and on groundwater - surface water interaction. As a test site with no significant anthropogenic impacts, the Tihany Peninsula in Hungary was an ideal area for the study. We address the following issues: i) How might a groundwater system, including groundwater-surface water interaction, be modified by predicted climate change?, ii) Given the variable groundwater levels and flow patterns, how will the water levels and fluxes be impacted around surface water bodies?, and iii) How sensitive are groundwater-related wetlands to these changes, and will they be maintained or will they eventually disappear? In order to answer these questions, two-dimensional transient numerical simulations were performed based on site-specific measurements and climatic prediction at the Tihany Peninsula. Results show that future climate trends can cause dynamic evolution and dissipation of transient groundwater flow systems, and the characteristic flow system hierarchy can change from nested flow systems to a set of single flow cells. Preservation of associated groundwater-dependent ecosystems would be challenging under these conditions since long-term climate change could potentially have serious consequences, including wetland disappearance. Understanding these transient processes in two-dimensions can also help to set-up three-dimensional site-specific models.