|YANLIN, ZHANG - Chinese Academy Of Sciences|
|GUODONG, C - Chinese Academy Of Sciences|
|XIN, L - Chinese Academy Of Sciences|
|XIAOLI, C - Chinese Academy Of Sciences|
|XUJUN, H - Chinese Academy Of Sciences|
Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2016
Publication Date: 3/13/2017
Citation: Yanlin, Z., Guodong, C., Xin, L., Xiaoli, C., Xujun, H., Flerchinger, G.N. 2017. Influences of frozen ground and climate change on hydrological processes in an alpine watershed: A case study in the upstream area of the Hei’he River, Northwest China. Permafrost and Periglacial Processes. 28(2):420-432. doi: 10.1002/ppp.1928.
Interpretive Summary: Climate warming is expected to affect the hydrological processes of cold regions by altering snowmelt and frozen-soil dynamics, particularly in discontinuous permafrost terrain. A new model developed by coupling the Simultaneous Heat and Water model (SHAW) with the distributed hydrological model (WEB-DHM) was applied to a river basin in China dominated by frozen soil, snowmelt and permafrost. Results indicate that under climate warming scenarios, the change in frozen soil dynamics and degradation of permafrost resulted in streamflow originating more from ground water flow rather than from direct surface runoff. This subsequently resulted in delayed and decreased streamflow. These findings have important ramifications to cold regions where hydrology is dominated by frozen soil, snowmelt, and permafrost, which accounts for approximately 55-60% of the land in the Northern Hemisphere.
Technical Abstract: Frozen soil prevails in cold regions and exerts significant influence on the hydrological cycle. In the context of climate warming, the spatial and temporal dynamics of frozen soil and hydrological processes also will change. How these changes inter-relate is a key challenge in studies of hydrological cycle and water resource assessment in cold regions. The objective of this study is to analyze and identify the impacts of frozen soil, climate warming, and permafrost coverage on the hydrological processes in mountainous cold regions. Thus, a physically based, distributed hydrological model with explicit full snow and frozen soil modules was tested in the upper reaches of the Heihe River basin. A simple calibration was performed and the model was evaluated. Results show that the model appears to be acceptable and promising. To obtain greater insight into the hydrological processes, climate-warming and frozen soil-free scenarios were developed and compared. Results show that when frozen soil was ignored, groundwater recharge and base flow was enhanced. The response time of river runoff to rainfall and snowmelt was delayed, and the hydrograph became smoother. Simulated river runoff was shown to decrease and the hydrograph became smoother with increased air temperatures associated with climate warming; the reason was attributed to higher evapotranspiration and increased depth of soil thawing.