Search

Quantitative and qualitative knowledge about the potential impacts of climate change on extreme hydrological events is crucial for water resource management and extreme risk management under climate change. This has theoretical and realistic implications to study and couple the climate system with hydrologic processes, to understand the system and solve related problems in water resources and extreme hydrology, such as decision making, plan management, environmental protection, and ecological balance. This paper reviews recent studies investigating climate change impact on hydrological extremes using a perspective of the integrated modeling framework comprising climate change scenarios, climate models, bias correction methods, hydrological modeling (model structure and parameterization), and reducible uncertainty arising from these sources characterized by a paucity of knowledge. The available research outcomes show the extreme high flows are likely to increase under climate change in the most parts of Europe, Asia, and the USA, but greatly vary and decrease in Africa and Latin America, which is highly variable and uncertain in space and time. Each component in integrated modeling has an important role in shifting and producing uncertainty in projected extreme flow. Among them, the climate model's discrepancy and hydrological models' structure are the more dominant source of uncertainty in projection of extreme high and low (or mean) flow in most of the regions, respectively. However, the quality of input data and hydrological model structures are the most dominant source of uncertainty in Africa, Latin America, and some parts of Asia. This indicated that these regions have strong hydrological cycle and higher physiographic heterogeneity. We believe that our existing knowledge and skills need to be improved and transformed into an accurate mathematical and physical representation, to minimize the uncertainty due to the effect of choices in the methodology chain. So, disentangling the aggregated uncertainty in the cascade modeling chain can be done by using variances, which can help understand the interaction effect and identify their contribution to the projected extreme flow. This comprehensive review can help modelers to identify and reduce uncertainty in projecting hydrological extremes and policy makers for full awareness of the various uncertainties to make a robust decision for water resources management under climate change. Article Highlights: This study provides a comprehensive review on reducing uncertainty in projecting hydrological extremes from the perspective of an integrated modeling framework Existing knowledge and skills need to be improved and transformed into an accurate mathematical representation The impact of climate change on hydrological extremes is highly variable and uncertain in space and time Uncertainties of the integrated modeling framework can be reduced by decomposing the aggregated uncertainty using variance analysis and/or the modeling chain [ABSTRACT FROM AUTHOR]

Roughly a third of Europe's water demand is satisfied by groundwater abstraction. Understanding how future changes in climate, weather, vegetation and land use will affect the transport of atmospheric water to the subsurface is critical for successful implementation of Europe's Water Framework Directive and to maintain groundwater as a high-quality water resource. This paper summarizes the known drivers of trends and variations in groundwater recharge (precipitation, evapotranspiration and vegetation, land use) in Central Europe and how they have changed in recent decades. From past observations and future climate projections, the foreseeable consequences for groundwater recharge under a changing climate are discussed. The paper focuses on the complex role of soils and vegetation at the interface between atmosphere and groundwater, and addresses open questions and possible new directions for research. Summarizing the evidence, land use and land-use change have a large control on recharge, but the influence of climate change is increasingly recognized. Central Europe's current transition from a temperate and relatively moist climate towards a more variable and Mediterranean-like climate may shift recharge patterns and increase the ratio of focused-to-diffusive recharge as precipitation patterns change and the frequency and intensity of climatic extremes (e.g., heavy rainfall, heatwaves, droughts, floods and wild fires) increase. However, uncertainty remains with regard to the dynamic response of Europe's vegetation to climate change as well as to human modifications of the water cycle (e.g., through irrigation, forest management, artificial recharge or urbanization), which currently challenges model-based predictions of future recharge. [ABSTRACT FROM AUTHOR]