A total water management analysis of the Las Vegas Wash watershed,Nevada

Climate change, land-use change, and population growth are fundamental factors affecting future hydrologic conditions in streams, especially in arid regions with scarce water resources. Located in the arid southwest within the Las Vegas Wash watershed, Las Vegas is one of the fastest growing metropolitan areas of the country. In the past 30?years, because of climate and land-use changes, it has experienced a decrease in clean water supply but an increase in water demand. To alleviate some of these problems, large amounts of water have been pumped into the city from different sources, such as Lake Mead, and the urban wastewater is treated and returned back to the reservoir for water augmentation. However, in the face of continual global climate change and urbanization in the watershed, long-term planning for sustainable water management is critical. This research was designed to provide a comprehensive analysis incorporating hydrologic modeling, population projection, land-use change modeling, and water management policies to examine the total water balance and management options in this arid and rapidly urbanizing watershed under various scenarios of climate regime, population growth, land-use change, and total water management programs for the year 2050.     

3S 技术在土地利用变化监测中的应用

土地是人类赖以生存和社会赖以发展的重要资源,是人类生存和发展的物质基础。实现土地利用变化信息的动态监测,对于土地资源合理规划、科学管理具有重要的意义。本文以滁州市不同时相Landsat5 TM遥感影像为主要数据源,结合其他辅助数据,利用3S技术提取土地利用变化信息,分析和评价了该区域土地利用的变化特征。结果表明：2004～2009年间该市土地利用类型发生较大变化,其中耕地面积明显减少,建设用地面积大幅度增加。     

LULUCF in the post-2012 regime: fixing the problems of the past?

One of the reasons why the Kyoto Protocol has been environmentally ineffective is the flaws in the land use, land-use change and forestry (LULUCF) accounting rules, including voluntary accounting for Article 3.4 activities, the adoption of a definition of forest management that allowed parties to preferentially include and exclude forest lands, and allowing parties with net emissions from LULUCF in 1990 to include deforestation emissions in their 1990 emissions base year. Three proposed amendments to the LULUCF rules for the post-2012 regime are discussed and analysed: (1) a force majeure rule, (2) a baseline-and-credit system for forest management and (3) an ‘emissions-to-atmosphere’ approach for harvested wood products. Although these proposals have the potential to significantly improve the accounting framework, there are still significant problems such as the failure to account for the biophysical effects of forest activities, uncertainties associated with the application of the forest management baseline-and-credit system and continuing optional coverage of Article 3.4 activities.     

多源遥感数据在土地利用图件更新中的应用--以怀柔区为例

本文阐述了以怀柔区为试验区,从遥感数据的应用着手,选择SPOT-5、QUICK BIRD、航空摄影像片三种遥感数据源对该区7幅土地利用基础图件作了更新,从而分析了三种数据源在土地利用基础图件更新中不同的适宜程度及其性价比,为土地部门选择合适的遥感数据源进行更新调查提供技术依据。     

基于本体结构的空间实体语义相似度计算模型

针对GIS领域语义相似度计算模型考虑的因素过于单一、有效性不足等问题。该文在分析现有的语义相似度计算模型的基础上,综合考虑属性相似度与结构相似度指标,同时引入概念间的继承等关系,提出了一种基于本体结构的地理空间实体语义相似度计算模型,在该模型的结构相似度指标中加入了深度、密度两种权重因子。最后,通过对土地利用分类中实体的语义相似度进行实验,说明其计算结果准确可靠,并能体现更多细节差异。     

不同土地利用数据对WRF模拟新疆高温天气的影响

本研究在WRF(v3.8.1)中使用MODIS 21类和USGS24类土地利用类型数据,模拟了新疆2017年7月9日的极端高温天气,并在对模拟温度进行了高度订正的基础上,对比了两种土地利用数据对2m温度预报的影响。结果表明：(1)MODIS和USGS在新疆地区的土地利用差异主要在阿尔泰山、天山以及南疆西部的昆仑山北部海拔3000米以上的高山带,相应地,使用USGS模拟的这些高山带2m气温明显高于使用MODIS的模拟值,最高偏高12℃左右,是全疆范围内两者偏差的极大值。(2)就新疆区域而言,使用USGS模拟的2m气温整体优于使用MODIS的模拟值,且USGS模拟的2m温度整体低于MODIS模拟的2m温度。两者的均多在2℃以内。(3)在伊犁河谷,MODIS土地利用类型主要为“旱地/草地”,USGS为“草地”和“农田/林地马赛克”。代表站点2m温度模拟多以高温偏低、低温偏高为主。(4)与MODIS相比,USGS中哈密地区 “农田/林地马赛克”所占比重明显增大。哈密地区多数代表站点高、低温均以偏低为主。(5)站点温度的高度订正多以调低为主,调高幅度最大值为1.9℃,出现在伊犁河谷的尼勒克站,调整幅度明显大于MODIS和USGS模拟2m温度的差值,由此可见温度高度订正的必要性。     

Numerical Simulations of Impacts of Urbanization on Heavy Rainfall in Beijing Using Different Land-Use Data

A summer strong convective precipitation event on 10 July 2004 over Beijing is numerically simulated in this paper, and the impact of urban heat island (UHI) on summer convective rain is investigated. The analysis reveals that a mesoscale convective cloud cluster system leads to this heavy rainfall event, suggesting the supply of moisture by the large scale circulation before the initiation of precipitation, a generally weaker UHI of 2-3℃existed in the urban area. Much like a sea breeze, the anomalously warm urban air created relatively low pressure, inducing the inflow of cooler rural air towards the urban center, which is favorable to the ascending motion and the formation of convective precipitation over the urban area. In addition, the numerical simulation of the strong convective precipitation event suggests that the simulated result of precipitation using the 2002 LANDSAT-7 land-use data with 30-m resolution is much better than that using the 1992-1993 USGS land-use data with 1-km resolution, whether in the magnitude of rainfall or in the location of precipitation. The simulation confirms to some extent that the UHI has a significant role in causing extreme rainfall event.     

广州市工业用地空间分异及其影响因素分析

基于定量分析,采用GIS技术,对广州市工业用地空间演变和分异特征进行了研究。分析表明,工业用地拓展以市中心区外围地带强度最大,其时空变化除了深受产业政策和城市发展战略的影响,在空间分异上,工业用地还与行政中心、道路交通和河流水面等因素密切相关,城市和交通的等级和功能不同对工业用地分异的影响不同。     

岩溶区土壤有机碳和团聚体的关系研究——以重庆市中梁山岩溶槽谷为例

研究了重庆市中梁山岩溶槽谷不同土地利用方式对土壤有机碳和团聚体稳定性的影响,在此基础上引入通径分析方法探讨有机碳与各粒径团聚体之问的关系.研究表明,土地利用方式对土壤有机碳、团聚体稳定性指数和团聚体保存几率影响明显:坡耕地有机碳含量仅为17.544(g/kg),分别比灌丛、橘林地、草地和菜地低61.14%、71.66%、74.43%和100.83%;团聚体稳定性指数依次为草地(2.394)>灌丛(2.383)>橘林地(2.085)>坡耕地(1.953)>菜地(0.865);团聚体稳定性与有机碳含量的相关性与土地利用方式有关,在灌丛和草地中明显正相关,在橘林地和菜地中呈负相关,而在坡耕地中相关性不明显;大粒径团聚体保存几率是决定有机碳含量的主要园子,5～10mm和3～5mm粒级的土壤团聚体对有机碳累积与稳定的决定系数分别为0.61和0.50.      

土壤环境因子对土下岩溶溶蚀速率的影响——以重庆金佛山国家自然保护区为例

通过野外溶蚀试片和测量土壤CO2浓度、水分、孔隙度、pH值和有机质含量的方法,探讨不同土地利用方式下土壤环境因子及其相互耦合对岩溶溶蚀速率的影响。研究结果表明,金佛山国家自然保护区不同土地利用方式下的平均溶蚀速率差异显著,总体表现为:竹林地>林地>草地>灌丛地>灌草丛地。不同土地利用方式下的土壤pH值与溶蚀速率呈很好的负相关,土壤水分含量、孔隙度与溶蚀速率呈正相关。山顶岩溶作用明显强于山下,这与重庆市百年一遇的大旱不无关系。土壤环境中CO2浓度、水分、孔隙度、pH值和有机质含量影响着岩溶溶蚀速率,同时这些土壤环境相互耦合也影响着岩溶溶蚀速率。