Abstract: Affected by climate warming and wetting, the number and area of lakes in the Qinghai-Tibetan Plateau have seen evident increases in recent years, resulting in lake overflow and even outbursts. Such threats to the security of lives and property of people and the safe operation of major engineering infrastructure can be alleviated by lake drainage project which diverts the overflow safely under control to the downstream area. However, in permafrost region, engineering activities and long-term water flow will lead to significant variations in hydrothermal regime. These variations will further affect local ecological environment and long-term stability of drainage projects. With the Yanhu Lake in Hoh Xil region as a background, we present a method combing InSAR, drone aerial photography, meteorological observation, ground temperature observation and geophysical exploration to establish a three-dimensional monitoring system on permafrost. The method considers the characteristics of permafrost in the region and the components of the drainage project. By using the present method, we could monitor synchronously the local meteorological conditions, the hydrothermal regimes of permafrost, and the stability of engineering structures. The monitoring work will provide data support for evaluating the impacts of drainage project on permafrost, and serve for prediction and early warning on the stability and service ability of engineering structures. The collected data will also offer important references for design, construction and maintaining of hydraulic infrastructure built on permafrost in the future.

Key words: lake outburst, drainage project, permafrost, field monitoring, Qinghai-Tibetan Plateau