TITLE:
The Gravity Environment of Zhouqu Debris Flow of August 2010 and Its Implication for Future Recurrence
AUTHORS:
Diandong Ren, Lance M. Leslie, Xinyi Shen, Yang Hong, Qingyun Duan, Rezaul Mahmood, Yun Li, Gang Huang, Weidong Guo, Mervyn J. Lynch
KEYWORDS:
Groundwater Fluctuation, Gravity Satellite Measurements, Storm Triggered Landslides and Flash Floods, Climate Change
JOURNAL NAME:
International Journal of Geosciences,
Vol.6 No.4,
April
2,
2015
ABSTRACT: This study investigates
the geological background of the August 7-8, 2010 Zhouqu debris flows in the
northwestern Chinese province of Gansu, and possible future occurrence of such
hazards in the peri-Tibetan Plateau (TP) regions. Debris flows are a more
predictable type of landslide because of its strong correlation with extreme
precipitation. However, two factors affecting the frequency and magnitude of
debris flows: very fine scale precipitation and degree of fracture of bedrock,
both defy direct observations. Annual mean Net Primary production (NPP) is used
as a surrogate for regional precipitation with patchiness filtered out, and
gravity satellite measured regional mass changes as an indication of bedrock
cracking, through the groundwater as the nexus.The GRACE measurements indicate a
region (to the north east of TP) of persistent mass gain (started well before
the 2008 Wenchuan earthquake), likely due to increased groundwater percolation.
While in the neighboring agricultural region further to the north east, there
are signal of decreased fossil water reservoir. The imposed stress fields by
large scale increase/decrease groundwater may contribute to future geological
instability of this region. Zhouqu locates right on the saddle of the gravity
field anomaly. The region surrounding the Bay of Bangle (to the southeast of
TP) has a similar situation. To investigate future changes in extreme
precipitation, the other key player for debris flows, the “pseudo-climate
change” experiments of a weather model forced by climate model provided
perturbations on the thermal fields are performed and endangered locations are
identified. In the future warmer climate, extreme precipitation will be more
severe and debris will be more frequent and severe.