水利工程对长江荆南三口水系连通功能变化的影响

为了揭示荆南三口地区水利工程与水系连通功能的定量关系,基于1954、1975、1990、2008和2016年5期的水利工程与水系连通功能的相关数据,运用集对分析和相关分析等方法,定量评价了水利工程对长江荆南三口水系连通功能的影响,结果表明：1）区内外水利工程与多年日均径流保证率、河道断流率、输沙效率的相关系数（R²）均＞0.5,皆达到显著性水平。2）自然功能3个模块的联系主值数基本呈下降趋势,但物质能量传递功能与生态维系功能下降尤为明显。1990年之前物质能量传递与生态维系功能处于一个较好的状态,1990年后这2项功能的等级已下降至“差”;社会功能3个模块的联系主值数的变化各不相同。洪涝防御功能一直处于上升状态,而水资源调配功能和水能与水运资源利用功能都在1954-1990年呈下降趋势,1990年后,水资源调配功能逐渐回升,水能与水运资源利用功能持续下降。3）1954-2008年自然功能等级和综合功能等级都有所下降,直到2016年才稍有回升,但升幅较小,等级较低;社会功能等级在1954-1990年较低,2008年以后回升,且明显高于自然功能等级。     

地理学视角下的城市棕地研究综述与展望

快速城市化背景下,城市棕地频现并已成为工业化与城镇化过程中的“毒瘤”。针对城市棕地研究空间视角缺乏和新型城镇化对老工业基地“改造更新与保护修复”的实践需要,在明确城市棕地基本概念和内涵的基础上,基于CiteSpace对2001~2017年Web of Science和CNKI期刊引文数据库中关于棕地研究的461篇英文和244篇中文文献,分析其发文数量、年度前沿热点、关键词、研究学科等知识图谱,梳理城市棕地空间识别方法、GIS空间数据库、评估体系、污染治理技术、景观规划设计、再利用机制及政策等方面的现有研究,提出地理学视角下的棕地再利用研究展望,即构建多学科交融的城市棕地研究框架、重视地理学视角下的棕地研究热点、完善统一的棕地概念体系、挖掘棕地空间识别方法及建立数据库、强化棕地再开发综合评价方法及指标体系构建、深入研究棕地再生模式与规划设计、注重典型城市和典型棕地再开发的实践研究。     

Discussion on Nonlinear Behaviors in Reservoir Flood Routing Modeling and Derived Uncertainties

Water Resources - In existing studies, external factors, such as hydrologic, hydraulic, and decision-making uncertainties, have been widely recognized as major risk source in reservoir flood...     

2018年威宁县茶山区域自动站雨量空间一致性检查分析

该文对2018年威宁县区域自动站雨量空间一致性进行分析,通过全年降水时空分布规律分析得出降水时空分布合理,通过分析发现茶山区域自动站全年雨量数据明显偏低,总结了区域自动站雨量数据异常的4种原因,进而对区域自动站的日常维护及汛前专项检查提供一些建议。     

The impact of natural vegetation restoration on surface soil moisture of secondary forests and shrubs in the karst region of southwest China

Soil moisture is crucial to vegetation restoration in karst areas, and climate factors and vegetation restoration are key factors affecting changes in soil moisture. However, there is still much controversy over the long-term changes in soil moisture during vegetation restoration. In order to reveal the changes in soil moisture during vegetation restoration, we conducted long-term positioning monitoring of soil moisture at 0–10 and 10–20 cm on secondary forests sample plot (SF, tree land) and shrubs sample plot (SH, shrub land) in karst areas from 2013 to 2020. The results showed that the aboveground biomass of SF and SH increased by 50% and 240%, respectively, and the soil moisture of the SF and SH showed an increasing trend. When shrubs are restored to trees in karst areas, the soil moisture becomes more stable. However, the correlation coefficients (R²) between the annual rainfall and the annual average soil moisture of SF and SH are 0.84 and 0.55, respectively, indicating that soil moistures in tree land are more affected by rainfall. The soil moisture of shrubs and trees are relatively low during the months of alternating rainy and dry seasons. Rainfall has a very significant impact on the soil moisture of tree land, while air temperature and wind speed have a significant impact on the soil moisture of tree land, but the soil moistures of shrub land are very significantly affected by rainfall and relative humidity. Therefore, during the process of vegetation restoration from shrubs to trees, the main meteorological factors that affect soil moisture changes will change. The results are important for understanding the hydrological processes in the ecological restoration process of different vegetation types in karst areas.     

高质量发展耦合协调时空格局演化及影响因素——以浙江省县域为例

综合运用耦合协调、空间关联分析和地理加权回归模型,对浙江省县域高质量发展耦合协调水平进行测度,进一步分析其空间演化特征及影响因素.结果 表明:①浙江省县域高质量发展整体上呈现出“东高西低、北高南低”的空间分异特征,高质量发展耦合空间格局以良好耦合为主,高质量发展协调水平以中级协调为主.②高质量发展耦合协调空间结构呈现出...     

Change in regional land subsidence in Beijing after south-to-north water diversion project observed using satellite radar interferometry

ABSTRACT

Over-exploitation of groundwater has caused severe land subsidence in Beijing during the past two decades. Since the middle route of South-to-North Water Diversion Project (SNWDP), the biggest water diversion project in China, started to deliver water to Beijing in December 2014, the groundwater shortage has been greatly alleviated. This study aims to analyze the impact of SNWDP on the spatiotemporal evolution of land subsidence in Beijing. Change in surface displacement in Beijing after SNWDP was retrieved and the spatiotemporal patterns of the change were analyzed based on long time-series Envisat Advanced Synthetic Aperture Radar (ASAR) (2004–2010), Radarsat-2 (2011–2014), and Sentinel-1 (2015–2017) satellite datasets using Permanent Scatterer Interferometric Synthetic Aperture Radar (PS-InSAR) techniques. Land subsidence unevenness index (LSUI) was proposed to represent the spatial unevenness of surface displacement. PS-Time approach was then adapted to examine the time series evolution of LSUI. The results showed that the InSAR measurements agree well with leveling measurements with R² over 0.96. Although the maximum annual displacement rate reached ?159.7 mm/year by 2017, over 57% of the area within 25 mm/year contour line showed decreasing or unchanged displacement rate after the south-north water delivered to Beijing. The settlement rate in Chaoyang-Dongbalizhuang (CD) subsidence center has decreased for 26 mm/year from 2011–2014 to 2015–2017. Only around 15% of the area experienced continued accelerating settlement rate through the three time periods, which was mainly located in the area with the compressible layer thickness over 190 m, while the magnitude of velocity increment considerably decreased after SNWDP. Land subsidence unevenness, represented by LSUI, developed more slowly after SNWDP than that during 2011–2014. However, LSUI at the edge of settlement funnel has kept developing and reached 1.7‰ in 2017. Decreasing groundwater level decline after SNWDP and the positive relationship (R² > 0.74) between land subsidence and groundwater level clearly showed impacts of SNWDP on the alleviating land subsidence. Other reasons include geological background, increasing precipitation, and strict water management policies implemented during these years.     

北京市建筑设计产业空间分布与区位选择

超大城市的城市空间结构调整需求日益迫切,城市内细分产业的空间分布及区位选择的研究也变得更加重要。以北京市为例,从微观视角分析了超大城市内部企业空间分布规律,以期为城市优化建筑设计产业空间结构提供理论支撑。运用核密度估计方法、Ripley’s K（d）函数以及负二项模型,分析了建筑设计企业的空间分布及其区位选择的影响因素。结果表明：① 服务型建筑设计企业集中分布在北京市五环内的中心城区;工程型建筑设计企业选址郊区化明显。② 服务型建筑设计企业的集聚尺度较工程型更大,不同细分行业的工程型建筑设计企业集聚尺度存在差异。③ 建筑设计企业在选址时受到政策、服务设施、运营成本、信息通达度和产业基础的影响,不同类型企业选址时的侧重点不同。与大规模企业相比,中小规模企业受成本要素的影响更大。与服务型建筑设计企业相比,工程型建筑设计企业受到政策的影响大。④ 选址在中心城区的建筑设计企业对服务设施和信息通达度等要素更为敏感,城郊的企业则主要受到成本要素和交通基础设施的影响。     

山东地区流动重力历史资料清理综述

系统地清理了山东测区1991年以来采用LCR-G型重力仪观测的21期历史资料,并对每期采用改建后的LGADJ数据处理软件进行单期平差、多期整体平差计算,查找历史资料出现的问题,最后对历史资料的异常点位识别和重力变化计算进行统计分析,为最后进行华北地区统一平差计算及统一入库提供有力保障。     

Heavy metal distribution and accumulation in the <Emphasis Type="Italic">Spartina alterniflora</Emphasis> from the Andong tidal flat,Hangzhou Bay,China

In order to study the heavy metal accumulation and distribution in the roots, stems, and leaves of Spartina alterniflora, we collected S. alterniflora samples and the associated sediments along three transects at the Andong tidal flat, Hangzhou Bay. Co, Ni, Cd, Pb, Cu, and Zn were mainly accumulated in the aerial parts (stems and leaves) of the plants, and their distributions depended on their mobility and their roles during the metabolism processes of S. alterniflora. The concentrations of Cu, Zn, Cd, Hg, and Pb were significantly enhanced with the increasing of heavy metal concentrations in the sediments, while those of Co and Ni remained relatively constant. Bioaccumulation factors results showed that the serious heavy metal contamination in the sediments from the transect A may overwhelm the accumulation capability of the plants. In addition, the physicochemical properties of the sediments and the pore water therein also play a role in the heavy metal concentrations and accumulations in the plants, because they can influence the behaviors and bioavailabilities of heavy metals during nutrition and bioaccumulation processes of the plants. The sediments with vegetation did not show significantly decreased heavy metal concentration with respect to the unvegetated sediments, although the plants did absorb heavy metals from the sediments. Principal component analysis and correlation analyses indicated that Co–Ni, Cu–Cd–Hg behaved coherently during accumulation, which may be ascribed to their similar accumulation mechanisms. This work provided essential information on the heavy metal accumulation by plants in a tidal flat, which will be useful for the environmental control through phytoremediation at estuaries.