Hydrological processes in land cryosphere: current status and some perspectives

Due to global warming effects, land cryosphere as a solid freshwater resource reservoir, has undergone drastic changes, directly affecting basin-scale hydrological processes．The study of cryosphere hydrology is therefore of great importance in regards to the utilization and management of basin-wide water resources．The cryosphere has, in recent years, generally shown a shrinking trend．The manifestations are manyfold: vanishing glacier area, mass loss, increased glacier runoff; decreasing snow area and snow water equivalent, as well as time advances in snow melting; shrinking area and thickening active layer for permafrost, as well as reduction in maximum freezing depth and freezing time for seasonally frozen ground, with impacts on runoff still being controversial．Difficulties in cryosphere-hydrology studies include large uncertainty in research data, lack of clear understanding of internal physical processes of cryosphere-hydrology, and lack of systematic and integrated research taking into account of all land cryosphere elements．Development of new observation technology and methods, development/application of physically-based cryosphere-hydrology modeling including complete cryosphere elements should be the focus of future land cryosphere-hydrology studies．