Hydrological Response of Alpine Wetlands to Climate Warming in the Eastern Tibetan Plateau

Alpine wetlands in the Tibetan Plateau (TP) play a crucial role in the regional hydrological cycle due to their strong influence on surface ecohydrological processes; therefore, understanding how TP wetlands respond to climate change is essential for projecting their future condition and potential vulnerability. We investigated the hydrological responses of a large TP wetland complex to recent climate change, by combining multiple satellite observations and in-situ hydro-meteorological records. We found different responses of runoff production to regional warming trends among three basins with similar climate, topography and vegetation cover but different wetland proportions. The basin with larger wetland proportion (40.1%) had a lower mean runoff coefficient (0.173 +/- 0.006), and also showed increasingly lower runoff level (-3.9% year(-1), p = 0.002) than the two adjacent basins. The satellite-based observations showed an increasing trend of annual non-frozen period, especially in the wetland-dominated region (2.64 day.year(-1), p < 0.10), and a strong extension of vegetation growing-season (0.26-0.41 day.year(-1), p < 0.10). Relatively strong increasing trends in evapotranspiration (ET) (similar to 1.00 mm.year(-1), p < 0.01) and the vertical temperature gradient above ground surface (0.043 degrees C.year(-1), p < 0.05) in wetland-dominant areas were documented from satellite-based ET observations and weather station records. These results indicate recent surface drying and runoff reduction of alpine wetlands, and their potential vulnerability to degradation with continued climate warming.