城市更新对房地产市场的时空影响效应:基于杭州市的实证研究

以杭州市为例,采用双重差分法研究城市更新对房地产市场的时空影响效应。研究结果发现： 城市更新在不同阶段对周边住宅价格产生的影响效应不同,项目建设和运营期分别对周边房价产生28.6%和32.0%的推升作用; 城市更新对周边住房价格的影响在空间上存在显著差异,对城市边缘区的提升作用比核心区高23.0%; 城市更新对周边房价影响随着距离增加显著降低,距离城市更新项目中心2.0 km以内、2.0~3.5 km范围对房价的推升作用分别为41.9%、24.9%和9.1%。最后建议政府完善房地产市场微观调控,建立完善长效机制。     

张掖城市主要功能用地演变特征及其动因分析

研究城市功能用地演替可以揭示出新时期中国城市功能空间演化的特征、趋势与形成机制,为城市管理提供理论依据。本文以张掖中心城区为研究范围,运用GIS工具及方法,定量分析了张掖市1981年以来居住用地、工业用地、公共服务用地三大功能用地的空间演变特征及其动因,进而绿洲城市空间的可持续发展提供指导。研究发现：张掖城市居住用地和公共服务用地呈逐步增加趋势,空间上呈“内聚→外散”的演变趋势,两者均由老城区向四周扩散,而工业用地先增加后减少,空间上呈“混杂→集中”的转变特征,整体上集中于东北部产业园区内。张掖城市功能用地演变是人口经济驱动、宏观政策调控、城市开发与生态环境博弈、交通线路牵引、城市规划引导等共同作用的结果。     

A simple assessment approach for winter wheat loss risk impacted by water stress

In this study, an empirical assessment approach for the risk of crop loss due to water stress was developed and used to evaluate the risk of winter wheat loss in China, the United States, Germany, France and the United Kingdom. We combined statistical and remote sensing data on crop yields with climate data and cropland distribution to model the effect of water stress from 1982 to 2011. The average value of winter wheat loss due to water stress for the three European countries was about ?931 kg/ha, which was higher than that in China (?570 kg/ha) and the United States (?367 kg/ha). Our study has important implications for the operational assessment of crop loss risk at a country or regional scale. Future studies should focus on using higher spatial resolution remote sensing data, combining actual evapotranspiration to estimate water stress, improving the method for downscaling of statistical crop yield data and establishing more sophisticated zoning methods.     

Modelling relational contexts in GEOBIA framework for improving urban land-cover mapping

In human cognition, both visual features (i.e., spectrum, geometry and texture) and relational contexts (i.e. spatial relations) are used to interpret very-high-resolution (VHR) images. However, most existing classification methods only consider visual features, thus classification performances are susceptible to the confusion of visual features and the complexity of geographic objects in VHR images. On the contrary, relational contexts between geographic objects are some kinds of spatial knowledge, thus they can help to correct initial classification errors in a classification post-processing. This study presents the models for formalizing relational contexts, including relative relations (like alongness, betweeness, among, and surrounding), direction relation (azimuth) and their combination. The formalized relational contexts were further used to define locally contextual regions to identify those objects that should be reclassified in a post-classification process and to improve the results of an initial classification. The experimental results demonstrate that the relational contexts can significantly improve the accuracies of buildings, water, trees, roads, other surfaces and shadows. The relational contexts as well as their combinations can be regarded as a contribution to post-processing classification techniques in GEOBIA framework, and help to recognize image objects that cannot be distinguished in an initial classification.     

Validation of Global Evapotranspiration Product (MOD16) Using Flux Tower Data from Panjin Coastal Wetland,Northeast China

Recent advances in remote sensing technology and methods have resulted in the development of an evapotranspiration(ET) product from the Moderate Resolution Imaging Spectrometer(MOD16). The accuracy of this product however has not been tested for coastal wetland ecosystems. The objective of this study therefore is to validate the MOD16 ET product using data from one eddy covariance flux tower situated in the Panjin coastal wetland ecosystem within the Liaohe River Delta, Northeast China. Cumulative ET data over an eight-day period in 2005 from the flux tower was calculated to coincide with the MOD16 products across the same period. Results showed that data from the flux tower were inconsistent with that gained form the MOD16 ET. In general, results from Panjin showed that there was an underestimation of MOD16 ET in the spring and fall, with Biases of -2.27 and -3.53 mm/8 d, respectively(–40.58% and -49.13% of the observed mean). Results for Bias during the summer had a range of 1.77 mm/8 d(7.82% of the observed mean), indicating an overestimation of MOD16 ET. According to the RMSE, summer(6.14 mm/8 d) achieved the lowest value, indicating low accuracy of the MOD16 ET product. However, RMSE(2.09 mm/8 d) in spring was the same as that in the fall. Relationship between ET and its relevant meteorological parameters were analyzed. Results indicated a very good relationship between surface air temperature and ET. Meanwhile a significant relationship between wind speed and ET also existed. The inconsistent comparison of MOD16 and flux tower-based ET are mainly attributed to the parameterization of the Penman-Monteith model, flux tower measurement errors, and flux tower footprint vs. MODIS pixels.     

黄河口埕岛海域粉土波致孔压现场监测

波浪会对海床产生反复的作用力,由此引起的土体颗粒间孔隙水压力变化是造成土体液化的主要原因。使用自行研发的孔压监测设备,对黄河口埕岛海域易液化区海底孔压进行了长时间、高精度的观测,并对孔隙水压力、波高以及潮位间的关系进行分析。监测结果显示,本次监测条件下波浪最大作用深度介于0.5～1.5 m之间,超过该作用深度后孔压无明显变化。土体内部孔隙水压力的变化主要由潮位和波高决定,潮位的作用可使孔压缓慢平滑的变化且对超孔压无影响;波高的作用可使孔压快速、剧烈地振荡并导致超孔压的出现。     

中国干湿格局对未来高排放情景下气候变化响应的敏感性

气候变化影响下干湿状况的区域分异格局如何变化是一个重要科学问题。基于参与耦合模式比较计划第五阶段(CMIP5)的5个全球气候模式(GCM),预估了RCP 8.5情景下未来百年中国干湿区面积的变化趋势,分析了干湿格局变化的敏感地区以及对气候变化响应的敏感性。结果表明:未来干湿格局变化以湿润区显著减少、干湿过渡区显著扩张为主要特征,特别是半湿润区面积在远期(2070-2099年)相对基准期(1981-2010年)增加了28.69%。升温2℃～4℃条件下,全国发生干湿类型转变的面积从10.17%增加至13.72%,尤其在淮河流域南部,这里主要受未来潜在蒸散增加的影响,湿润区向南明显退缩从而转变为半湿润区。总体上,随着未来升温加剧,中国干湿格局对气候变化响应的敏感性将可能增强。     

Governance,Gender and the Appropriation of Natural Resources: A Case Study of ‘Left-Behind’ Women’s Collective Action in China

China’s rapid urbanization has created large scale of population migration, resulting in many villages being dominated by “left-behind” women, and weak governance of those collectively owned resources. The situation has required these women to take up the functions of decision-making and governance as a remedial mechanism as well as a new path. Based on a case study in a typical hollowing-out village in central China, this paper explores an example of left-behind women’s collective action to prevent the over-exploitation of community and resources. It finds out that although traditionally excluded from public activities and marginalized, the “left-behind” women were able to mobilize and enhance collective action. When empowered, they are growing fast with endurance and courage, and as capable as anyone of defending the common-pool resources. It suggests that the left-behind women offer a new governance option for those population hollowing out rural areas.     

Genetic Structure and Haplotype Pattern of Marine Planktonic Ostracod (Porroecia spinirostris) from South China Sea Based on Mitochondrial COI Gene

Ocean Science Journal - Ostracods (Crustacea, Ostracoda) are small bivalved crustaceans, contributing to the marine zooplankton community. They are widely distributed and are relatively abundant...