Monitoring-priority assessment of geological hazards around the Xiaolangdi reservoir using multisource remote sensing

Abstract

Abandoned mine workings and loess-bank retreat around reservoirs are jointly affected by legacy excavation, water-level fluctuations, and slope structure, making a single PS-InSAR displacement metric insufficient for monitoring prioritization. This study integrates 88 ascending Sentinel-1A IW-VV scenes, optical imagery, a digital elevation model, engineering-geological records, and field investigations to construct a risk priority index (RPI) combining deformation magnitude, spatial dispersion, field damage, and reservoir coupling. Ranking stability is evaluated under a prescribed distribution of criterion weights. Across seven zones, maximum cumulative subsidence ranges from 21.4 to 199.6 mm. Jianggeda has the highest RPI. Dakuailing-Tangling rises from fifth in the displacement-only ranking to second after mine-subsidence and bank-retreat evidence is incorporated. Nanyao shows smaller displacement but remains a monitoring priority because of reservoir proximity and a predicted retreat width of 52-253 m. The integrated approach converts deformation and geological evidence into a comparable and auditable basis for monitoring prioritization; the resulting scores represent relative priorities rather than hazard probabilities.