Hydro-climatic extremes shift the hydrologic sensitivity regime in a cold basin

Area of Science:

• Hydrology
• Climate Science
• Environmental Science

Background:

• Climate extreme events increasingly disrupt hydrological processes, impacting water availability and sediment dynamics.
• The relationship between hydrological variability and climatic extremes is under-researched, especially in cold regions facing climate change.
• Cold regions are critical for agriculture and urban development, making their hydrological systems vulnerable.

Purpose of the Study:

• To investigate the impact of shifting climatic extreme patterns on hydrological regimes in the Ishikari River Basin (IRB).
• To develop a yield-based dichotomy framework for analyzing climate extreme impacts on water and sediment yields.
• To project future hydrological changes under different Shared Socioeconomic Pathways (SSPs) scenarios.

Main Methods:

• Utilized a modified Soil and Water Assessment Tool (SWAT).
• Integrated downscaled Coupled Model Intercomparison Project Phase 6 (CMIP6) General Circulation Model (GCM) climate projections.
• Employed Shared Socioeconomic Pathways (SSPs) scenarios for future climate projections.

Main Results:

• Identified significant annual variability in water and sediment yields linked to extreme climate events.
• Hot-dry conditions correlated with lower water and sediment yields.
• Increased cold extremes were associated with higher sediment yields in the IRB.
• Hotter and drier patterns may establish new hydrologic regimes and shift yield classification thresholds.
• SSP585 projections indicate intensified water availability and sediment transport, increasing flood and sedimentation risks.

Conclusions:

• Climate extremes significantly influence hydrological regimes, with distinct impacts from hot-dry versus cold conditions.
• Future climate change, particularly under SSP585, poses substantial risks to water availability and sediment transport in the IRB.
• Adaptive water management strategies are crucial to mitigate the impacts of altered hydrological regimes due to global climate change.