There are distinct seasonal changes in both precipitation and air temperature in the UTHF. Annual mean air temperature has increased since 1990s, to an extent similar or slightly exceeding the reported global warming rate of 1.1 °C. Mean annual precipitation in the UTHF is lower than the nationwide average, due to low frequencies of both Typhoon arrival and Baiu front stagnation. Snow cover period appears at the end of November and lasts until the beginning of April, with a mean maximum snow depth of 85.6 cm typically observed in late February. Seasonal fluctuations in stream discharge are driven primarily by snowmelt in spring and rain-runoff responses in summer and autumn. Both low and flood flows are hydrological risks in the region. Catchment geology affects particularly on summer low flow. While spring flows may contribute to stream discharge, no comprehensive investigation has yet been conducted in the UTHF. Although fragmented, available information on streamwater chemistry in and around UTHF suggested a strong influence of catchment geology on the chemistry.