Recent land cover changes on the Tibetan Plateau: a review

This paper reviews the land cover changes on the Tibetan Plateau during the last 50 years partly caused by natural climate change and, more importantly, influenced by human activities. Recent warming trends on the plateau directly influence the permafrost and snow melting and will impact on the local ecosystem greatly. Human activities increased rapidly on the plateau during the last half century and have significant impacts on land use. Significant land cover changes on the Tibetan Plateau include permafrost and grassland degradation, urbanization, deforestation and desertification. These changes not only impact on local climate and environment, but also have important hydrological implications for the rivers which originate from the plateau. The most noticeable disasters include the flooding at the upper reaches of Yangtze River and droughts along the middle and lower reaches of Yellow River. Future possible land cover changes under future global climate warming are important but hard to assess due to the deficits of global climate model in this topographically complex area. Integrated investigation of climate and ecosystems, including human-beings, are highly recommended for future studies.     

延安地区大气中PM_(10)浓度水平及其变化特征

利用延安地区2006—2008年大气中可吸入颗粒物PM10的监测资料,分析了PM10的浓度水平、变化规律及其影响因素。延安地区PM10的年平均浓度为153μg/m3,超过国家环境空气质量标准年平均值2级浓度限值70μg/m3的1倍多,这与当地高的PM10区域背景水平(平均值为109μg/m3)紧密相关。PM10质量浓度水平具有明显的季节性,春季最高,冬秋其次,夏季最低。PM10日均值浓度超过国家环境空气质量2级标准的日数占全年的40%,其中春季达66%。PM10质量浓度日变化呈明显的双峰双谷型特征,与风速的日变化有明显的反相关关系。1mm降水量对PM10的湿清除能力按冬、春、秋、夏依次递减。延安地区出现西风或偏西风时PM10平均质量浓度高,但就累积影响而言,处于主导风向上的西南风要比其他方向高40~50μg/m3左右。     

山东半岛冷流降雪过程的统计分析

对威海地区2001-2006年1、2、11、12月所有冷流过程的温压湿等气象要素进行分析,结果表明:地面偏西北风有利于冷流过程的发生;冷流降水量与海气温差有着较强的正对应关系,而与大气相对湿度没有明显的对应关系.相关系数进一步表明了850 hPa温度与海温之差直接决定了地面冷流降水量的大小.从探空指教和垂直湿位涡分布可以看出.,管大气近于弱的对流稳定,但仍不影响对称不稳定的产生.     

基于Sentinel-3 OLCI影像的巢湖藻蓝素浓度年内动态遥感监测

藻蓝素(PC)是水体蓝藻的指示性色素,其浓度反映了蓝藻生物量,利用卫星遥感监测藻蓝素浓度年内动态对蓝藻水华的有效防控有着重要意义.根据不同季节的巢湖藻蓝素浓度实测数据与同期Sentinel-3 OLCI影像,构建机器学习回归反演模型,应用于巢湖2019年OLCI影像集上,对巢湖藻蓝素浓度的空间分布、年内变化进行遥感监测...     

基于系统动力学的巢湖流域水资源承载力动态预测与调控

湖泊流域水资源承载能力动态预测与调控是维护湖泊生态安全、保障社会经济健康持续发展的重要基础和手段.本文以巢湖流域为研究对象,提出基于系统动力学的湖泊流域水资源承载力动态预测技术和试验优化调控方法.首先以县(市)为基本单元构建水资源承载力系统动力学模拟与动态预测模型;再从空间上将各县(市)耦合为流域系统整体模型,并通过敏感性分析筛选量质要素调控指标;最后采用正交试验设计确定流域水资源承载力优化调控方案.结果表明:由于流域内产业规模的扩大以及城镇化率的提升,20172050年巢湖流域水资源承载状态值整体呈恶化趋势,并于2030年以后将长期处于超载状态,通过对影响要素针对性优化调控后,20172050年流域水资源承载状态均达到临界或可载.研究表明本文提出的方法对于促进区域社会经济环境协调发展和改善流域水资源承载力具有较好的实际应用价值.     

SUSTAINABLE DEVELOPMENT OF THE SERIOUSLY POLLUTED CITIES IN CHINA——Taking Benxi City as an Example

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Soil evolution features of debris flow waste-shoal land

The reclamation and utilization of debris flow waste-shoal land plays an important role in the mitigation and control of debris flow hazards, which thus contributes a lot to the exploitation of insufficient land resources in mountainous areas and the reduction of losses caused by debris flow. The aim of this paper is to discuss the features and mechanism of soil evolution of debris flow waste-shoal land so as to search for the available modes of its reclamation and utilization. The Jiangjiagou Ravine, a typical debris flow ravine, was selected to study soil evolution features of debris flow waste-shoal land based on the analysis of soil physieochemical properties and soil microstructure. It was found that the soil evolution rates of debris flow waste-shoal land varied with different modes of reclamation. For the land which had been reclaimed for less than lO years, soil evolved most rapidly in paddy fields, and more rapidly in dry farmland than in naturally restored waste-shoal land. For the land which had been used for more than lo years, the soil evolution rates of dry farmland, naturally restored waste-shoal land and paddy farmland decreased in the file. For the same utilization period of time, significant differences were recognized in soil evolution features under different modes of reclamation. Analysis data showed that soil clay content, soil thickness, the psephicity of skeleton particles and contents of microaggregates （〈0.02 mm） in paddy farmland were all highest. Soil nutrients and porosity of dry farmland were better than those of paddy farmland and naturally restored waste-shoal land, and those of paddy farmland were superior to those of naturally restored waste-shoal land. Paddy farmland characterized by rapid pedogenesis, stable evolution and high utilizability was the priority candidate for the reclamation and utilization of debris flow waste -shoal land.     

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盾构超近距离侧穿铁路桥桩保护方案探讨

郑州地铁某盾构区间超近距离侧穿铁路桥梁桩基,受地面空间及隧道与桥桩间净距限制,无法采用隔离桩等常规保护措施.结合工程实际情况提出"盾构通过范围内土体注浆加固"、"桥梁承台加固"以及"注浆+承台加固"三种措施,利用数值模拟手段,对盾构侧穿施工期间,不同保护方案下桥桩的变形规律进行了分析研究.研究结果表明,采用"盾构通过范...     

测井解释中煤层含气量评价方法对比研究

随着煤层气勘探的不断深入,对煤层含气量预测精度提出了更高的要求。基于煤层含气量测井响应特征,分析测井参数与含气量的相关性,提出MIV（Mean Impact Value）技术与LSSVM（Least Squares Support Vector Machine）结合的测井参数优选策略,优选最优测井参数作为网络建模的输入自变量组合,通过粒子群算法优化LSSVM网络核心参数,最后构建一套适用于煤层含气量预测的MIV-PSO-LSSVM模型。在此基础上,分别对比分析LSSVM、PSO-LSSVM、MIV-LSSVM和MIV-PSO-LSSVM模型对煤层含气量的预测性能,并与传统多元回归方法进行了对比,利用拟合优度和均方根误差对此5类模型进行评价。结果表明：PSO优化下的LSSVM模型预测精度得到有效提升,结合MIV方法优选测井参数可大幅度改善神经网络建模性能,MIV-PSO-LSSVM模型可实现煤层含气量高精度预测,为煤层气勘探及其储层评价提供新的技术支撑,且本研究的建模策略及思想可广泛应用于其他机器学习建模研究领域。