冻土水文研究进展

Research Review on Hydrology in the Permafrost and Seasonal Frozen Regions

冻土改变了区域水热条件、产汇流过程、产流量多寡及年内/际变化,冻土水文成为寒区生态—水文过程的核心环节。系统总结了国内外冻土水文研究进展,包括冻土水热传输特征,特殊的产汇流过程,流域尺度水平衡,以及各种水热传输物理模型和流域尺度水文模型。未来冻土水文的发展应在数据和方法积累的基础上,进一步探索产汇流过程机理,并建立完善的分布式冻土水文物理模型,定量探索冻土变化对区域/流域水资源和生态的影响。

Hydrology in the permafrost and seasonal frozen regions becomes the most important segment in the eco-hydrology processes in the cold region,since the water and energy conditions,runoff generation and concentration are changed by the presence of frozen soil.Such understanding is important for regional environmental protection and water management decisions.This paper try to provides an review of research on hydrology in the permafrost and seasonal frozen regions,and introduce the characteristics of the water and heat flow,the peculiar mechanisms of runoff generation and concentration,and the qualities of runoff and water balance in the cold regions.Water and heat flow through frozen soil are affected by the formation and presence of ice in the porous matrix in comparison to unfrozen soils.The formation of ice is influenced by soil characteristics,temperature and initial water content,and lead to the diversity of thermal and hydraulic conductivity in the frozen soil,which are need more concern in future research.With respect to frozen ground,its influence on infiltration,percolation and evapotranspiration in both permafrost and seasonal frozen regions result in the clearly distinguishable peculiarities from the hydrology of other geographical zones.Where present,frozen soil acts as a semi-impermeable medium,restricting deep percolation,increasing soil moisture and enhancing runoff in spring.In summertime,the soil water storage capacity in the thawing part of the soil,the depth of which changed over time,controls the runoff characteristics.Excess water at summertime just before soil freezing,which is controlled by the amount of summer rainfall,is stored as ice during winter.This water storage stabilizes the rate of evapotranspiration.Besides the introduction of mechanism of hydrology in the permafrost and seasonal frozen regions,some models deal with water and heat transfer processes and hydrological processes are summarized.In the early time,these models used in the cold regions were upbuilt through appending influence of frozen soil to tradition hydrological models,and then some researchers attempt to develop some specialized spatially-distributed models of runoff generation in the permafrost regions at the present time.However,some the hydrological processes and parameters in these models,which characterized the peculiarities in the cold regions,are still experiential and conceptual.The future research on hydrology in the permafrost and seasonal frozen regions should ravel the mechanisms of runoff generation and concentration on the base of the accessorial data and new technique,develop a cold regions distributed physics-based hydrological model,and quantify the influence on water resource and ecosystem in cold regions.