Threshold Definition for Monitoring Gapa Landslide under Large Variations in Reservoir Level Using GNSS

The triggering threshold is one of the most important parameters for landslide early warning systems (EWSs) at slope scale. In present work, a velocity recommended an system Gapa in Southwest China, which was reactivated by impoundment large reservoir behind Jinping’s first dam. Based on GNSS monitoring data over last five years, defined novel method, implemented forward and reverse double moving average time series. As deformation strongly related to fluctuations water levels, crucial level also reduce false warnings from alone. recognition importance geological evolution, evolution process topping sliding described this study help understand its behavior predict potential trends. Moreover, based improved Saito’s three-stage model, set as “attention level”, because current stage considered be between initial constant stages. At present, mainly consists six surface displacement sites observation site. If daily recorded each site exceeds 4 mm/d and, meanwhile, below 1820 m above sea (asl), likely accelerations will released relevant sites. thresholds are always discretely exceeded about 3% annual days, they frequently June (especially mid-June). provide efficient effective way judging verified application. work presented provides critical insights into development reservoir-induced large-scale landslides.