Ecological Vulnerability Evaluation and Change Analysis of the Tianshan Area Along the Pipeline of the “West-to-East Gas Transmission” Project Based on the SRP Model

The “West-to-East Gas Transmission” project has accelerated economic development in Xinjiang and the central-western regions along the pipeline. However, as the pipeline traverses multiple cities and counties in the Tianshan region, it has significantly impacted the local ecology, necessitating a comprehensive assessment. This study employs the Sensitivity-Resilience-Pressure (SRP) model to construct an ecological vulnerability assessment system for the Tianshan region, aiming to analyze changes in ecological vulnerability and evaluate the environmental impact of the “West-to-East Gas Transmission” project. The results indicate that, spatially, ecological vulnerability in the Tianshan region increases progressively from northwest to southeast. Temporally, from 2000 to 2010, the mean Ecological Vulnerability Index (EVI) exhibited a decreasing trend, with values of 0.476, 0.464, and 0.462, primarily shifting to lower vulnerability levels. From 2010 to 2020, the EVI showed an increasing trend, with values of 0.462, 0.466, and 0.468, predominantly transitioning from heavy to very heavy vulnerability. The key influencing factors of ecological vulnerability in the Tianshan region, ranked by importance, are NDVI, NPP, land use type, annual precipitation, and aridity. Furthermore, the “West-to-East Gas Transmission” project consists of three main pipelines (Lines 1, 2, and 3), for which buffer zone analyses were conducted at radii of 1 km, 3 km, and 5 km. The results indicate that ecological vulnerability patterns remained consistent across different buffer zone sizes, and larger buffer radii were associated with lower mean EVI values along the pipeline. After pipeline construction, the mean EVI along Line 1 decreased from 0.566 to 0.550, while the EVI along Line 2 remained nearly unchanged. In contrast, the mean EVI along Line 3 increased from 0.434 to 0.447. Regarding changes in ecological vulnerability levels, along Line 1, the area of improvement (18.83%) exceeded the area of deterioration (1.09%), primarily due to the high proportion of very heavy vulnerability zones (>80%), which are more likely to transition to lower vulnerability levels. Along Line 2, ecological vulnerability remained relatively stable, indicating minimal environmental impact. However, along Line 3, the improvement area (3.81%) was significantly smaller than the deterioration area (20.52%), suggesting that construction of Line 3 had a more pronounced ecological impact, leading to greater degradation of the ecological vulnerability along its route.