Objective Understanding the distribution of water-induced pipeline hazards and their environmental controls is fundamental to risk assessment and mitigation planning.

Methods Using long-term observations of water-induced pipeline hazards along the northern piedmont of Yumu Mountain in the Hexi Corridor from 2015 to 2025, this study develops a dual-index system comprising a point-development index and a linear-erosion index to quantify spatiotemporal hazard evolution and examine the controls exerted by rainfall, slope gradient, overlapping alluvial fans, and steep scarps.

Results Over time, both indices show an overall decline as engineering mitigation measures provide cumulative protection during pipeline operation. Specifically, the decline is greater for gully-type hazards than for slope-type hazards. However, extreme rainfall events can still trigger significant hazard responses over short time scales. Spatially, the point-development index is jointly controlled by gully-type and slope-type hazards, with gully-type hazards contributing more strongly. The linear-erosion index is primarily controlled by slope-type hazards.

Conclusions Heavy-rainfall frequency and intensity strongly influence the point-development index, particularly for slope-type hazards. The longitudinal slope gradient at the mountain front is positively correlated with the linear-erosion index. Water-induced hazards are concentrated in zones of overlapping alluvial fans. Whether pipelines cross or run parallel to steep scarps is a dominant control on the alternating occurrence of gully-type and slope-type hazards. The point-development index is negatively correlated with the distance between the pipeline and steep scarps, whereas the linear-erosion index is positively correlated. These findings provide a theoretical basis for characterizing hazard distributions along linear infrastructure using two complementary indices and for planning hazard prevention and mitigation.