Climate Change and Climate Variability

Oral Abstract

Natural and Anthropogenic Land Cover Change and Its Impact on the Hydro-climate over the Three-river Headwaters Region

Wednesday, January 4
1:30 PM - 3:00 PM
Location: 2nd & 3rd Meeting Room

Located in the northern Tibetan Plateau, the Three-River Headwaters region is the origin of the Yellow River, Yangtze River and Mekong River. Due to natural and human-induced land cover change, the streamflow over headwaters of Yellow River and Yangtze River decreased by 17% and 15% during the second half of last century. However, since the implementation of the “Graze for Grass Project” and “Three-River Headwaters Region Reserve Project”, the coverage for grassland and lake has increased, so does the streamflow. To investigate the effects of the land cover change on the regional hydro-climate over the Three-River Headwaters region, ground and remote sensing of meteorological, ecological and hydrological observations are combined with high-resolution hydro-climate modeling for an integrated assessment.


Recently, a Conjunctive Surface-Subsurface Process (CSSP) land surface model with fully coupled two-dimensional surface water, quasi-three-dimensional soil water and groundwater models, was evaluated over mountainous areas in southwestern USA in a hyper-resolution manner. Results showed that including finer-scale soil and topographic information reduced the errors of simulated soil moisture and energy fluxes, although it did not necessarily improve the variability at very high resolution (e.g., from 4 km to 1 km) without hyper-resolution meteorological forcing. The lateral transport of surface water decreased the heterogeneity of soil water over wet regions during wet seasons even at a coarser resolution, which influenced the regional water and energy cycle. In addition, the lateral transport of soil water affected the water balance at hyper-resolution of 100m or finer, especially over the valleys and channels where the topographic gradient is large.


Simulations are now being conducted with the CSSP model over the Three-River Headwaters region, configured by a multisource high-resolution (0.0625 degree) meteorological forcing, a 1-km soil texture and a 30-m topography datasets. The CSSP hyper-resolution configuration will also be implemented into its host climate model, the Regional climate-weather research and forecasting (CWRF) model, for investigating the effects of land cover change on terrestrial hydrological cycle in a land-atmosphere coupled manner. This research is targeted at attributing the changes in terrestrial water cycle before and after the ecological reserve project in a mountainous area that is regarded as a sentinel of climate change.

Xing Yuan

Professor
Institute of Atmospheric Physics, Chinese Academy of Sciences

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Natural and Anthropogenic Land Cover Change and Its Impact on the Hydro-climate over the Three-river Headwaters Region



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