Mapping Permafrost Features that Influence the Hydrological Processes in the two forked valley in the Source Area of the Yellow River (SAYR), NE Qinghai-Tibet Plateau, China

Thursday, 27 July 2017: 10:30 AM
Paul Brest West (Munger Conference Center)
Shuhui Gao1,2, Huijun Jin1, Dongliang Luo2 and Qingfeng Wang2, (1)Chinese Academy of Sciences, State Key Laboratory of Frozen Soils Engineering, Beijing, China, (2)Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China
Degradation of near-surface permafrost due to changes in the climate is expected to impact the hydrological, ecological and biogeochemical responses of the Source Area of the Yellow River (SAYR) on the Northeast of Qinghai-Tibet Plateau (QTP), China. Little is known, however, about the hydrological processes in a two forked valley located on the discontinuous permafrost areas and their influences on permafrost evolution? We employed the Electrical Resistivity Tomography (ERT) method, topographic mapping (GPS), meteorological observation, hydrology section and borehole drilling to explore the interaction between hydrological processes and taliks development at a site on the SAYR. The study site is located at 34°39.0′N,97°19.5′E , 4420 m a.s.l
On the two forked basin, 11 ERT profiles are laid on the valley basin. And ERT results show that affected by the lithology character and the local hydrology, the permafrost depth is about 20-30m and it is deeper inside the valley basin. And the permafrost is shallow or disappears in the edge of the basin with the deepest permafrost depth at about 10m. The ERT results of the permafrost distribution are consistent to the field investigation and the borehole monitoring. And on the basis of the rock and soil physics relationship, we can get the empirical water content and the permeability coefficient in the two-forked valley. And it can describe how uncertainties the relationship between the permafrost distribution and the taliks considering the factors of vegetation distribution, the stream distribution, the mean annual ground temperature (MAGT), the porosity, and the fluid conductivity, etc. Taliks emerge around the main stream, and surrounds the stream the active layer is deeper. The vegetation coverage around the main stream is higher than that on the edge of the basin.

The study of active layer of the high-mountain permafrost in SAYR demonstrates that the evolution of the permafrost was not only driven by climate change and the elevation but also local condition such as local topography and streams.

Such a process-based qualitative understanding is crucial for assessing the impact of climate change, in conjunction with the local topography and hydrogeology, on the evolution of small valley on SAYR.