Search Results (3)

The impact of a tunnel construction on the groundwater system depends on various parameters and cannot be easily predicted. Along these lines, a deep understanding of the hydrological relationship between tunnels and surface water is considered of vital importance for ensuring safety during railway construction. Upon completion, the North Taihang Tunnel will be one of four extra-long railway tunnels running through the natural ecotope and level-3 protection areas of the Tianshengqiao National Geological Park in Fuping County, Hebei Province. It will be 1 km away from the Tianshengqiao Nine Falls, which is known as a breathtaking landscape feature in Northern China. Local government, societies, and railway design units have raised concerns about whether the construction and operation of the North Taihang Tunnel will affect the Tianshengqiao Nine Falls. To effectively address this issue, in this work, hydrogeological mapping and hydraulic potential-energy calculations were performed in conjunction with hydrochemical and geological structure analyses. The groundwater system units in the study area were divided and the water source of the nine-level waterfall was determined retrospectively. In addition, the recharge of groundwater to the nine-level waterfall was calculated, the hydrogeological properties of the linear structure were analyzed, and the dominant channels of underwater discharge in surface water were compared and studied. The extracted results indicated that: (1) The Tianshengqiao Nine Falls represent a seasonal fall landscape, which is mainly supplied by surface water formed by precipitation and a low proportion of groundwater supply. (2) The water bodies of the North Taihang Tunnel project and Tianshengqiao Nine Falls belong to two independent groundwater systems. (3) No linear structure that connects these two groundwater systems has yet been discovered. It is widely accepted that a minor possibility of hydraulic connection might be present between the North Taihang Tunnel and Tianshengqiao Nine Falls. This work analyzed the water quantity of Nine Falls, determined the hydraulic relationship between the tunnel project and the waterhead of the Nine Falls, and addressed all stakeholder concerns. The conclusions could provide technological support for the scheduled construction projects. Full article

As a response to climate changes, permafrost has deteriorated and the hydrologic process has undergone significant alterations in high-cold regions. The response mechanism still remains unknown. The characteristic contribution was calculated using the random forest (RF) algorithm, AdaBoost algorithm, and gradient-boosted decision tree (GBDT) algorithm. A comprehensive evaluation model was constructed to evaluate the contribution of climate changes to the headwaters of the Yellow River and the influence of permafrost degradation as well as climate-permafrost cooperation on runoff changes. The selected characteristic vectors were chosen as datasets for the support vector machine (SVM) and RF algorithms. A model was constructed for the prediction of permafrost degradation and runoff changes based on climate data. Results demonstrated that climate variables influencing the mean depth-to-permafrost table (DPT) were ranked according to their contributions: air temperature > evapotranspiration > wind speed > relative humidity (RHU) > sunshine duration > precipitation. The descending rank of climate and permafrost variables according to their contributions to runoff was the following: precipitation > sunshine duration > permafrost coverage > evapotranspiration > relative humidity (RHU) > mean DPT > wind speed > maximum DPT > air temperature. The model demonstrated good prediction results. The outputs can provide scientific references in applications related to water resources and the protection of ecologically vulnerable areas in high-cold regions. Full article

The riparian buffer width on watersheds has been modified over the last decades. The human settlements heavily used and have significantly altered those areas, for farming, urbanization, recreation and other functions. In order to protect freshwater ecosystems, riparian areas have recently assumed world recognition and considered valuable areas for the conservation of nature and biodiversity, protected by forest laws and policies as permanent preservation areas. The objective of this work was to compare parameters from riparian areas related to a natural watercourse less than 10 m wide, for specific purposes in Law No. 4761/65, now revoked and replaced by Law No. 12651/12, known as the New Forest Code. The effects of 15, 30 and 50 m wide riparian forest in water and soil of three headwater catchments used for sugar cane production were analyzed. The catchments are located in the Environmental Protection Area of Uberaba River Basin (state of Minas Gerais, Brazil), legally protected for conservation of water resources and native vegetation. A field survey was carried out in the catchments for verification of land uses, while periodical campaigns were conducted for monthly water sampling and seasonal soil sampling within the studied riparian buffers. The physico-chemical parameters of water were handled by ANOVA (Tukey’s mean test) for recognition of differences among catchments, while thematic maps were elaborated in a geographic information system for illustration purposes. The results suggested that the 10, 30 or even 50 m wide riparian buffers are not able to fulfill the environmental function of preserving water resources, and therefore are incapable to ensure the well-being of human populations. Therefore, the limits imposed by the actual Brazilian Forest Code should be enlarged substantially. Full article