Land consolidation and eco-environmental sustainability in Loess Plateau: A study of Baota district,Shaanxi province,China

Journal of Geographical Sciences - Eco-environmental sustainability is the basis for sustainable development in ecologically fragile areas. Land consolidation plays an important role in...     

New insight into the structure of nanocrystalline ferrihydrite: EXAFS evidence for tetrahedrally coordinated iron(III)

Ferrihydrite (Fh) is a short-range ordered nanocrystalline iron(III) (oxyhydr)oxide that has been recognized to play an important role in contaminant sequestration and in iron cycling in geological and biological systems. Despite intensive research for the two last decades, the structure of Fh is still a subject of debate. In the present study, we report extended X-ray absorption fine structure (EXAFS) spectroscopy data collected on a large set of ferrihydrites and model compounds samples including especially nano-crystalline maghemite (Mh), goethite (Gt), and akaganeite (Aka). This set of EXAFS data recorded at cryogenic temperature over a wide energy range allows us to precisely determine the Fe-O mean distance (〈Fe-O〉) in the first coordination shell of iron for this large set of iron (oxyhydr)oxides. Our EXAFS analysis includes both classical shell-by-shell fits of Fourier-filtered and unfiltered data as well as analysis of Fe-O distance distribution in the first coordination shell of iron using the Landweber iteration method. 〈Fe-O〉 determined by these complementary EXAFS analyses are similar: 〈Fe-O〉 is shorter in Mh (1.96 ± 0.01 Å) that contains 37.5% of tetrahedral iron, than in Gt (2.01 ± 0.01 Å), Aka (2.00 ± 0.01 Å) and hematite (Hm) (2.01 ± 0.01 Å) that do not contain tetrahedral iron. 〈Fe-O〉 for the five Fh samples investigated (1.97 ± 0.01 Å) was found to be slightly longer than in Mh and significantly shorter than those in Gt, Aka and Hm. This short 〈Fe-O〉 distance in Fh indicates the presence of significant amount of tetrahedrally coordinated iron(III) in all Fh samples studied, which ranges between 20 ± 5% and 30 ± 5% of total iron. In addition, our analysis of Fe-Fe distances observed by EXAFS is consistent with a Keggin-like motif at a local scale (∼5 Å) in the Fh structure.     

Regional ecosystem services relationships and their potential driving factors in the Yellow River Basin,China

The Yellow River Basin(YRB) occupies an important position in China’s socioeconomic development and ecological conservation efforts. Understanding the spatiotemporal characteristics of the relationships among multiple ecosystem services(ESs) and their drivers is crucial for regional sustainable development and human-earth system coordination. This study simulated food production(FP), water yield(WY), net primary production(NPP), soil conservation(SC), and habitat quality(HQ) in the YRB from 2000...     

转型期农村土地整治的基础理论与模式探析

农村土地整治是适时补充耕地、盘活存量土地、优化城乡用地、强化集约用地和提升土地产能的重要途径。本文针对中国城乡发展转型进程中出现的农村空心化加剧发展和农村居民点用地“不减反增”等突出问题,分析了科学推进农村土地整治的战略目标与现实意义,阐释了农村土地整治中土地资源优化配置、农村土地“三整合”、农村空心化“生命周期”、克里斯泰勒中心地理论等相关的基础理论,深入探讨了农村土地整治的区域差异性模式、城乡一体化模式、“一整三还”综合模式、统筹协同决策模式及其创新机制。     

Integrated GNSS with different accuracy of track database for safety-critical railway control systems

The primary object of this research is to test and to assess a tightly coupled GNSS and railway track data system for railway applications. One of the key features of this system is its ability to take into account uncertainties in both GPS observables and the spatial railway network data. Since trains travel on pre-defined fixed routes, 3-D positioning becomes a 1-D positioning problem that fixes the position of the train along the track. The spatial railway network database is then used to estimate the other two coordinates. In this way, the accuracy of the railway network database is crucial for the integrated positioning system. Unfortunately, the necessary accuracy of the railway network database is not known. Additionally, the integrity and availability performance of GNSS-based train location system are also essential for the safety-critical railway control systems. The required navigation performances (RNP) for the safety-critical railway applications in terms of accuracy, integrity and availability are investigated. We test different accuracies of the track database for the integrated system. Based on the result, when the GPS is integrated with the track database, the accuracy, integrity and availability are improved. The higher the accuracy of the track database, the better the positioning accuracy is guaranteed. For the integrity and availability performance, the result shows that the medium accuracy of the track database is more cost-effective for the integrated system.     

GIS-based Effect Assessment of Soil Erosion Before and After Gully Land Consolidation: A Case Study of Wangjiagou Project Region,Loess Plateau

The Loess Plateau is one typical area of serious soil erosion in the world. China has implemented ′Grain for Green′(GFG) project to restore the eco-environment of the Loess Plateau since 1999. With the GFG project subsidy approaching the end, it is concerned that farmers of fewer subsidies may reclaim land again. Thus, ′Gully Land Consolidation Project′(GLCP) was initiated in 2010. The core of the GLCP was to create more land suitable for farming in gullies so as to reduce land reclamation on the slopes which are ecological vulnerable areas. This paper aims to assess the effect of the GLCP on soil erosion problems by studying Wangjiagou project region located in the central part of Anzi valley in the middle of the Loess Plateau, mainly using the revised universal soil loss equation(RUSLE) based on GIS. The findings show that the GLCP can help to reduce soil shipment by 9.87% and it creates more terraces and river-nearby land suitable for farming which account for 27.41% of the whole study area. Thus, it is feasible to implement the GLCP in places below gradient 15°, though the GLCP also intensifies soil erosion in certain places such as field ridge, village land, floodplain, natural grassland, and shrub land. In short, the GLCP develops new generation dam land and balances the short-term and long-term interests to ease the conflicts between economic development and environmental protection. Furthermore, the GLCP and the GFG could also be combined preferably. On the one hand, the GFG improves the ecological environment, which could offer certain safety to the GLCP, on the other hand, the GLCP creates more farmland favorable for farming in gullies instead of land reclamation on the slopes, which could indirectly protect the GFG project.     

基于卫星遥感的输油管廊沿线的地物识别研究

基于eCognition软件进行研究区域面向对象的信息提取,对研究区进行多尺度影像分割的实验,找到适合影像地物信息提取的尺度及参数、分类规则,并对研究区的影像数据进行验证,通过eCognition分类结果与传统分类和基于GBDT分类算法结果的对比,说明面向对象的特征提取算法更适用于几何信息和结构信息丰富的高分辨率图像.     

Geodetection analysis of the driving forces and mechanisms of erosion in the hilly-gully region of northern Shaanxi Province

Journal of Geographical Sciences - This paper analyzes the spatial variation in soil erosion in the loess hilly-gully region of northern Shaanxi Province, China. It sums up existing research,...     

Land engineering and its role for sustainable agriculture in the agro-pastoral ecotone: A case study of Yulin,Shaanxi Province,China

Journal of Geographical Sciences - With global climate change, the agricultural light-temperature potential productivity in the agro-pastoral ecotone has increased. This offers a good opportunity...     

影像变化检测技术辅助的地表覆盖分类成果质量检查技术研究

针对地理国情监测项目地表覆盖分类成果的分类精度检查特殊性,提出了一套基于高分辨率遥感影像变化检测技术辅助成果质量检查的技术路线,并结合工程实践开展了成果检查试验,试验结果表明:该技术路线能有效检查出成果中存在的漏更新、误更新等典型问题,有效提高检查的效率与准确性,可为地理国情监测项目中地表覆盖分类成果质量控制提供技术参考。