Natural ecosystems provide human society with very important products and services. With the rapid increase in population and the over-exploitation of natural resources, humans are continually enhancing the production of some services at the expense of others. This paper estimates changes in ecosystem services, and the relationship between these services in the Guanzhong-Tianshui Economic Region of China. These ecosystem changes are of great significance to the sustainable development of this economic region. The concept of production possibility frontier (PPF) is applied to evaluate the trade-offs and synergy between carbon sequestration, water yield and soil retention. Three land use strategy scenarios–planning, exploitation and protection–are applied to evaluate potential changes in ecosystem services. This study reveals noticeable trade-offs between carbon sequestration, soil retention and water yield, with synergy between carbon sequestration and soil retention. There are synergies between carbon sequestration, water yield and soil retention in the three scenarios. The protection scenario is the most favourable land use strategy for regulating ecosystem service capacity. This scenario results in the highest carbon sequestration, water yield and soil retention. The results could have implications for natural capital and ecosystem services planning, management and land use decision-making. 相似文献
Acta Geotechnica - The pre-bored grouted planted (PGP) pile is a composite pile consisting of a precast concrete pile and the cemented soil around the pile. Thus, the PGP pile shaft capacity is... 相似文献
Shielding effects have a significant influence on the estimation of soil displacements for jacked piles, which have received minimal attention in previous studies. To include the shielding effects, a novel model was established for the soil compacting displacements of two jacked piles based on the strain path method and the source–sink method. The corresponding closed-form analytical expressions were also derived. Soil compacting displacements were calculated using the proposed method and the previous method, which disregard the shielding effects. The results showed that the soil displacements obtained based on the shielding effects are larger than those obtained when the effects are disregarded in the frontal direction, whereas the opposite results are obtained in the dorsal direction. The shielding effects have significant influence on the soil displacements in the frontal direction and those in the dorsal direction. Consequently, shielding effects should be included in the calculations of soil compacting displacements in the frontal and dorsal directions. An in situ test was also performed to investigate the reasonability of the proposed approach. Computed displacements were compared with the measured data. The results showed that the proposed model effectively predicts practical displacements, which demonstrates the validity of the proposed model. Further research is needed to verify the practicality of the described method.
The choice of a river training strategy is extremely important for the Lower Yellow River (LYR). Currently, the wide-river training strategy applies in the training of the LYR. However, remarkable changes in the hydrological processes in the Yellow River basin, as well as immediate pressure from socio-economic development in the Yellow River basin, make it necessary to consider if there is a possibility to change the river training strategy from wide-river training to narrow-river training. This research investigates the impacts of different river training strategies on the LYR through numerical simulations. A one-dimensional (1-D) model was used to simulate the fluvial processes for the future 50 years and a three-dimensional (3-D) model was applied to study typical floods. The study focused on river morphology, the results show that if the present decreasing trend in both water discharge and sediment load persists, the deposition rate in the LYR will further decrease no matter what strategy is applied. Especially, narrow-river training can achieve the aim to increase the sediment transport capacity in the LYR compared with wide-river training. However, if the incoming water and sediment load recovers to the mean level of the last century, main channel shrinkage due to sedimentation inevitably occurs for both wide-river and narrow-river training. Most importantly, this study shows that narrow-river training reduces the deposition amount over the whole LYR, but it provides little help in alleviating the development of the “suspended river”. Instead, narrow-river training can cause aggradation in the transitional reach where the river pattern changes from highly wandering to meandering, further worsening the “hump deposition” there. Because of uncertainty regarding future changes in hydrological processes in the Yellow River basin, and the lack of feasible engineering measures to mitigate “suspended river” and “hump deposition” problems in the LYR, caution should be exercised with respect to changes in the river training strategy for the LYR. 相似文献
