Ecological Impacts Associated with the Qinghai-Tibet Railway and Its Influencing Factors: A Comparison Study on Diversified Research Units.

The ecological impacts of the construction and operation of the main transport infrastructure on the Qinghai-Tibet Plateau cannot be disregarded. Based on different sections, buffers, bilateral sides, and periods, the authors of this study explored the ecological changes along the Qinghai-Tibet Railway through an integrated analysis of the landscape fragmentation index and ecological service value calculation from 2000 to 2020, as well as the influencing factors of differentiated trends, using multinomial logistic regression. It was discovered that there was heterogeneity among the sections, buffers, and bilateral sides in both the landscape fragmentation index and the ecological service value. It was also found that there was recoverability in the operation period, compared to the construction period. The negative correlation between the landscape fragmentation index and the ecological service value was only significant in 2020, which was not enough to fully explain the negative effect between them. Distinct human and natural circumstances have resulted in different consequences. However, regions far away from the main settlement areas, and with lower population densities, could aid in the simultaneous recovery of the ecological service value and landscape fragmentation index. According to these findings, prior studies may have exaggerated the ecological impact of the Qinghai-Tibet Railway. However, it should be highlighted that, in a location with a delicate ecological environment, it is still crucial to consider regional development, infrastructure construction, and ecological protection synchronously.

A Nonlinear Constitutive Model for Remoulded Fine-Grained Materials Used under the Qinghai-Tibet Railway Line.

Using undrained triaxial shear tests, this study investigates the mechanical properties of fine-grained materials (silty clay and sand) which are extensively used for China's Qinghai-Tibet Railway (QTR) under different confining pressures (σ3) and freezing temperatures (T). The results show that a reduction in T causes an increase in the shear strength and elastic modulus of all the materials tested in the present study. In addition, the freezing of the silty clay has no significant effect on the type of soil behaviour (strain-hardening), whereas the freezing of the sand changes its strain-hardening behaviour to strain-softening. Supposing that the deviatoric stress-strain curves of the silty clay and sand can be divided into two segments due to a reverse bending point, it was assumed that the first segment follows a hyperbolic function. Meanwhile, the second segment is also a hyperbola, with the reverse bending point as the origin and the residual strength as the asymptote. Accordingly, a nonlinear relation constitutive model that considers σ3 and T is derived. All model parameters are identified. The reasonability of the new model was verified using the test results of the materials. A comparison of the predicted and test results shows that this model can well simulate the deviatoric stress-strain response in the failure process of the tested materials. In particular, it can reflect the residual deviatoric stress after the materials' failure.

Domino effect of a natural cascade alpine lake system on the Third Pole.

Third Pole natural cascade alpine lakes (NCALs) are exceptionally sensitive to climate change, yet the underlying cryosphere-hydrological processes and associated societal impacts are largely unknown. Here, with a state-of-the-art cryosphere-hydrology-lake-dam model, we quantified the notable high-mountain Hoh-Xil NCALs basin (including Lakes Zonag, Kusai, Hedin Noel, and Yanhu, from upstream to downstream) formed by the Lake Zonag outburst in September 2011. We demonstrate that long-term increased precipitation and accelerated ice and snow melting as well as short-term heavy precipitation and earthquake events were responsible for the Lake Zonag outburst; while the permafrost degradation only had a marginal impact on the lake inflows but was crucial to lakeshore stability. The quadrupling of the Lake Yanhu area since 2012 was due to the tripling of inflows (from 0.25 to 0.76 km3/year for 1999 to 2010 and 2012 to 2018, respectively). Prediction of the NCALs changes suggests a high risk of the downstream Qinghai-Tibet Railway, necessitating timely adaptions/mitigations.

Effects of the opening of the Qinghai-Tibet Railway on municipal solid waste management generation in Lhasa.

Lhasa, the capital of Tibet, is located on the Tibetan Plateau. Accelerated economic development and flourishing tourism resulting from the opening of the Qinghai-Tibet Railway (QTR) have increased solid waste generation and contamination in recent years. Using data from Lhasa Statistical Yearbooks and previous studies, this study estimates the future population of permanent residents and tourists using the least squares method to extrapolate the population from 2015-2025, and evaluates the effects of the QTR on municipal solid waste (MSW) generation in Lhasa and estimates future MSW generation. There were approximately 1.35 million tourists in 2008 when the QTR had been operating for 2 years and MSW generation was approximately 470 tons per day. The amount of MSW generated increased dramatically with time after opening the QTR. This study estimates that MSW generation will reach 962 tons per day in 2025. Due to the existence of the QTR, increasing numbers of people are traveling to Lhasa, and tourism has driven the development of the local economy. During the studies, the proportion of MSW produced by tourists increased from 2.99% to 20.06%, and it is estimated that it will increase to 33.49% in 2025. If the current trend continues, Lhasa will face significant challenges from garbage disposal. This study analyzes the current situation of urban garbage treatment in Lhasa, and it suggests several options for improvement to MSW generation, transportation equipment, disposal, and resource recycling.

The Hygienic Survey on Drinking Water Source Quality in Qinghai Section of Qinghai-Tibet Railway Areas / 环境与健康杂志

Objective In order to understand the quality of drinking water sources and the environment of the Qinghai-Tibet Railway areas. Methods In 2002-2004, the first and second phase of the project of Qinghai-Tibet Railway, 37 sampling sites were chosen in the dry and rainy seasons and the water samples were analyzed according to the national standard test methods. Results In the first phase of the project, the eligible rates of the 39 test indexes of the water sources of 23 sampling sites in the Qinghai-Tibet Railway areas were 82%-95% in the dry season and some decreased in the rainy season. In the second phase, the eligible rates of the test indexes of the water sources of 14 sampling sites were 50%-100% in dry season and in the rainy season, the trend was the same as in the first phase. Conclusion Among the 37 water resources in the Qinghai-Tibet railway areas,the percent of gradeⅠ, gradeⅡ, grade Ⅲ and above grade Ⅲ water source was 67.57%,13.51%,2.70% and 16.22% respectively, some water sources can not be used as the drinking water sources due to the bad quality.