基于时序特征的黄河三角洲土地覆盖动态及驱动力分析

综合不同土地利用类型的Landsat影像时序特征和面向对象分割方法,分析1985-2018年现代黄河三角洲土地覆盖时空特征,探讨土地覆盖变化的驱动机制。结果表明:1985-2018年间研究区天然湿地面积大幅减少,共减少9.9847×104 hm²,其中沼泽和草甸湿地面积减少尤为明显,而人工湿地面积则逐年增加,年平均增加率达54.66%,主要是盐田养殖场和水稻种植面积的增大;社会经济因素对研究区土地覆盖的影响程度高于水文因素;输沙量是影响研究区土地覆盖变化的主要水文因素,实测径流量的减少进一步导致天然湿地向旱地类型转化;人口和GDP变化对人工湿地面积增加的正相关作用比较显著,而天然湿地面积的减少则与该两个指标的负相关关系比较明显。     

Land use externalities, open space preservation, and urban sprawl

Parcel data on residential land conversion are used to investigate how land use externalities influence the rate of development and modify policies designed to manage urban growth and preserve open space. Several “smart growth” policies are found to significantly influence land conversion, including a development clustering policy that concentrates development and generates preserved open space. In addition to directly affecting a parcel's hazard rate of conversion, this policy is found to affect neighboring parcels' conversion by generating a positive open space externality that hastens their development. The implication that the clustering policy could generate a more sprawled pattern of development is explored using spatial simulation.     

The housing question in Japan

This article first examines how bad housing conditions are in Japan based on international comparisons. The next question is whether the extremely high land prices in Japan can be explained by economic logic. We then turn to more specific housing policy questions that are peculiar to or important in Japan, such as the tax advantages of owning land that have caused under-utilization of land and the reasons why the average size of Japanese rental housing is so small.     

Legalization of drugs: Effects on the workplace

In the last few years bipartisan support for legalizing drugs has grown to a surprising level. Because of the lack of involvement of the business community in this debate, we surveyed the human resource managers of 127 firms about their perceptions of the effects of legalization. Their responses were uniformly negative, with expectations that drug use, absenteeism, worksite crime, and liability costs would increase, while the quality and quantity of work would decline. They also forecast increases in drug testing, performance monitoring, and education and rehabilitation programs as a result.     

宅基地使用权转让的法律路径——兼评《物权法草案》第162条

设计宅基地使用权的转让制度既要充分考虑我国农村的现实，又要保持相关规则之间的协调。“一户一宅”原则宜表述为“一户只能申请一处宅基地”。物权法对宅基地使用权的转让可以进行必要的限制，但不宜作出绝对的禁止性规定，应当允许宅基地使用权在一定条件下和一定范围内转让。非本集体经济组织成员受让宅基地使用权有其必要性，但必须予以限制。宅基地使用权转让的登记制度，可统一采用“未经登记，不发生物权的效力”的处理模武。     

广播谈话节目中细节的运用与处理

广播谈话节目是广播节目主持人与嘉宾、听众之间的以思想观念、感情心理的深层交流为目的的双向交流节目。怎样使节目能够不断出新、出彩从而吸引听众呢?细节的运用与处理大有文章可做。细节分为两种，即必然的细节和偶然的细节。必然的细节更多地运用在节目的开场和结尾，它可以很好地烘托节目主题；偶然的细节，它可以使节目”形散而神不散”、自然流畅、浑然天成。有人说细节成就精品就是这个道理。在谈话节目中，必然细节和偶然细节是可以根据实际情况灵活运用于开场白、主体部分及结束语中的，决不能视为固定不变的公式。     

水土流失遥感调查中植被覆盖度因子提取研究

植被覆盖度是水土流失的主要影响因子,而利用遥感影像判读可以快速有效地获得大范围的植被覆盖度。简要介绍了水土流失遥感调查中植被覆盖度因子提取的方法。基于遥感与实地野外调查数据,采用MODIS时序数据融合高分遥感数据的方法,以湖南省蓝山县为试验区,对植被覆盖度因子进行了提取。结果表明,该方法提取植被覆盖度因子的结果较理想。提出的植被覆盖度因子提取方法对今后的水土流失动态监测研究具有重要的理论意义和实践意义。     

梅溪流域城镇化进程对山前平原区洪涝过程的影响

为探究城镇化进程引起土地利用类型变化对山前平原区洪涝过程的影响,以梅溪流域下游平原区的洪濑镇为例,分析了2002—2018年梅溪流域上游山区和下游平原区的土地利用类型变化,并基于多情景数值模拟,研究了流域尺度内土地利用类型变化对山前平原区洪涝过程和地表淹没状况的影响。结果表明：随着梅溪流域耕地和林地面积减少、城镇建设用地增加,上游山区的径流系数和峰值流量均增大,下游山前平原区的淹没状况更加严重;上游山区的城镇建设用地增加使山区骤发洪水峰值流量增大、峰现时间提前,主要影响地表平均最大淹没水深和平均峰现时间;下游平原区的城镇建设用地增加使内涝发生的时间提前,主要影响地表平均淹没历时。     

Among-site variability in environmental and management characteristics: Effect on nutrient loss in agricultural tile drainage

Water quality issues, including harmful and nuisance algal blooms (HNABs), related to nitrogen (N) and phosphorus (P) exported from agricultural lands persist in the Great Lakes region. Previous work examining N and P loss from agricultural fields in portions of the United States (US) and Canada (CA) that drain into Lake Erie, consistently indicate significant nutrient loss from fields in Indiana and Ohio, US compared with those in southwestern Ontario, CA. The primary objective of this study was to examine variation in environmental and management characteristics from 30 sites (US: n = 28, CA: n = 2) located within the Lake Erie Basin and subsequently determine the influence of among-site variation on edge-of-field N and P losses. Using principal component analyses (PCA), we found that among-site variation was predominantly controlled by broad-scale patterns in fertilizer management practices and soil properties; however, N and P loss metrics were largely unexplained by these gradients. As such, fine-scale variability and the interaction of environmental and management characteristics at individual sites more strongly influenced N and P loss. Ultimately, these results further emphasize the importance of site- and nutrient-specific management plans that are needed to mitigate N and P losses from agricultural fields.     

长江经济带农业水资源利用效率时空差异分析

长江经济带水资源总量充沛,但人均水资源量以及单位面积耕地占有量处于较低水平;农业用水量超过供水总量的50%,而农业水资源利用效率低。研究长江经济带农业水资源利用效率对保护长江具有重要的现实意义。基于Malmquist-Panel Data两阶段模型,对长江经济带农业水资源利用效率的时空差异特征及其影响因素进行了分析研究。分析结果表明:经济发展水平、第一产业固定资产投资额、水资源禀赋、节水农业发展水平、"长江经济带"国家战略的实施、区域变量以及部分时间变量等对农业水资源利用效率具有显著的正向影响,而种植结构即粮食播种面积占比则有着显著的负向影响;长江经济带农业水资源利用效率时空差异特征明显。因此,对于长江经济带,应因地制宜、合理规划农作物种植结构;同时,加强地区间的技术交流与合作,实现长江经济带整体发展与各区域特色发展协同共进。