重力异常分层分离方法改进及应用:以安徽五河地区为例

本文在原有位场分层分离技术的基础上,提出了动态改进型插值切割算子.通过理想模型实验和谱分析,证明了改进算子对异常源产生的重力场有更好的分离效果.使用新方法对安徽省五河地区布格重力异常进行了分离和分析,分离后的浅部地球物理特征与地表地质调查结果的吻合度高,从而验证了改进算子的有效性和准确性.在结合基础地质资料和分离后的地球物理特征的基础上,进一步分析了五河地区构造格架、区域岩浆岩及红层盆地的空间分布和形态特征,并获取了对研究区内郯庐断裂系各条断裂的延伸、形态和相互关系的新认识.     

南方水库热分层消亡时期水体混合特征及其驱动机制

稳定分层的深水水库常在冬季发生“翻库”现象,继而导致水库的整体水质下降,影响饮用水安全问题。为探究南方水库热分层消亡时期水体混合特征,在冬季2019年11月—2020年2月对南宁市天雹水库水体理化指标开展长序列原位监测,并结合水体垂直扩散系数,分时期(热分层期、减弱期、完全混合期、形成期)刻画水库热分层消亡全过程中水温T、溶解氧DO的剖面变化特征,探讨了气象因子(气温、太阳辐射、风速等)与水动力因子(水体垂直扩散系数K_z)对水体理化指标的影响。结果显示:桉树人工林区水库热分层消亡期温度分层与溶解氧分层变化不同步,溶解氧分层的破坏较水温分层的破坏出现滞后,其结构失稳是气温及太阳辐射共同作用的结果;期间水体垂直扩散系数变化范围0.16～380.36 m²/d,均值为30.46 m²/d,表层K_z变化的主要控制因子为气温变化,且较T及DO而言,表层K_z对气温的变化更加敏感(R_Kz=-0.44,R_T=0.25,R     

南方水库热分层消亡期混合层深度及缺氧区时空变化特征——以南宁市天雹水库为例

湖库热分层消亡引起的突发性水质恶化现象引起了广泛的关注,我国南方水库大多是暖单次混合型湖泊,每年混合一次,导致水库水质周期性下降,但目前对南方水库热分层消亡过程的高频监测研究较少。为探究我国南方水库热分层消亡期水体混合过程的时空变化规律及驱动因素,以广西南宁天雹水库为例,于冬季热分层消亡期(2019年11月—2020年2月)对水库多点位水体理化指标开展原位监测,并利用自建气象站获取气象水文数据。结果表明:(1)水库热分层消亡期间,过渡区水深较浅可在短期内达到完全混合状态且缺氧区同步消失;而湖泊区混合过程整体滞后于过渡区,混合层深度由6.85 m增加至13.65 m,缺氧区逐渐减小,缺氧指数(AI)由0.40减小至0.07,直至水体完全混合后缺氧区消失;水库过渡区较湖泊区提前约40 d达到完全混合状态。(2)气象因子是引起热分层结构变化的主要因素,气温(T)、辐射(R)与混合层深度(MLD)呈现显著负相关(R_T=0.927、R_R=0.925,P<0.01),风速(WS)与MLD呈现显著正相关(R_WS=0.728,P&...     

云南石屏县地质灾害特征及成灾规律研究

云南石屏县地处云南高原南缘,县域总体地势北高南低,倾向红河河谷,地质构造复杂,地质环境条件比较脆弱。经实地调查,其地质灾害的类型主要有滑坡、崩塌和泥石流,这些地质灾害点大多沿断裂带集中分布。石屏县山高坡陡的地形地貌是地质灾害发生的重要控制因素,雨季的强降雨及人类生产活动常常是地质灾害产生的诱发因素。     

基于水质-水位二元响应关系推求过水型湖泊适宜生态水位研究

适宜的生态水位能够反映湖区生态系统的多种需求,是湖泊长期稳定健康运转的基本保障.目前湖泊适宜生态水位的推求大多侧重恢复天然水位情势.然而过水型湖泊承担着防洪、供水、航运等多种功能,频繁的人类活动导致湖泊水位情势异常复杂.同时随着社会经济的快速发展,水质恶化对过水型湖泊生态系统造成了较大的负面影响,仅恢复天然水位情势难以反映过水型湖泊的生态需求.因此,在IHA-RVA法的基础上,本文针对过水型湖泊吞吐性强的特点,利用水质-水位二元响应关系系统地提出了一套逐月修正过水型湖泊适宜生态水位阈值,并确定适宜水位变动率的方法.以洪泽湖为应用实例,结果表明:1)根据湖泊水文情势和入湖污染物变化情况,湖泊调度周期可以划分为平水期(1-4月)、泄水期(5-6月)、蓄水前期(7-9月)和蓄水后期(10-12月);2)各时期内,洪泽湖水位和水质呈现较强的相关性,其中平水期、泄水期和蓄水后期水质均随着水位上升而下降,平均Pearson系数达-0.77,仅在蓄水前期水质随水位上升而改善;3)现阶段洪泽湖的自净能力和污染物滞留比例竞争关系激烈,逐月适宜生态水位阈值为:12.92～12.99、12.79～12.99...     

Spatial Distribution Prediction of Habitats Selected by Wintering Common Cranes(Grus grus) at Yeya Lake Wetlands under Land Use Change

Yeya Lake Wetlands are the largest site for wintering birds in Beijing, where common cranes(Grus grus)winters every year. The land cover of the wetlands has undergone distinct changes from 2006 to 2009 as a result of human activities. In 2006, a survey of the presence/absence of the birds was completed using a line-transect method.A predictive model of habitat suitability was derived by using logistic regression and geographic information system.Then, this habitat suitability model was applied in 2009 under the land use change to test the effectiveness of the model and compare the habitat suitability between 2 years. The negative associations between Grus grus presence and increasing elevation, distances to grassland, to farmland, to bush, and to road suggested a preference for low lying areas in close proximity to food and cover. While the positive associations with distances to buildings and to water suggested a preference for low disturbance areas. The areas of suitable habitats increased from 2006 to 2009, and the spatial model was effective in both years. Habitat preference of Grus grus varied in land use types, therefore habitat suitability dynamics might possibly relate to land use change and thereby be predictable through a geographic information system approach. Although the obtained model had a good fit in both years, it was suspected that if frequent human activities continued, the number of Grus grus might decrease or disappear in this area. According to the field survey, the spacious water area was essential for wintering birds and the risks from loss of lake water and unfavorable crop practices might dramatically change the quality of each type of land use.     

Contribution of Community Forestry in Poverty Reduction: Case Study of Multiple Community Forests of Bajhang District,Nepal

In Nepal, nearly half of the total land is covered by forest, which holds a potentially important position in promoting rural livelihoods and in alleviating rural poverty. The rural landscape that encompasses an agrarian economy, a fragile ecology, and a complex and differentiated society is changing rapidly in Nepal today. Although poverty alleviation has been one of the top priorities for national development since 1976, poverty still remains widespread, persistent and it is also an acute problem in Nepal, where people are in a state of deprivation with regard to incomes, clothing, housing, healthcare, education, sanitary facilities and human rights. Thus, Nepal is considered as one of the poorest countries in South-Asia, with 25.2% people living below the poverty line. The objective of this study was to assess changes in poverty of forest users brought on by the community forestry program, in order to analyze the level of participation in community forestry management activities. For this study, Bajhang district was chosen as the study site, which is one of the poorest and most remote districts in the country of Nepal. Different Participatory Rural Appraisal methods such as face-to face interviews, focus group discussions and key informants’ interviews including secondary data were used to gather information. The findings showed that the forest users’ participation in meetings, discussion and other activities, like community forestry management or silvicultural operation related to community forestry, was high. The assessment found that 42.3%, 32.6% and 25.1% of respondents strongly agreed, agreed and were neutral, respectively, towards the idea that poverty reduction from community forests had occurred. The results showed almost all the respondents were depended upon agriculture and/or forest resources for their livelihoods. Different ecosystem services such as ethnomedicines, aesthetic value and ecotourism, control of soil erosion/land-slides, water recharge and soil fertility have increased due to the decomposition of leaf litter. This was apparent from the formulation of community forests. Poverty in rural areas of the country is still higher than in urban areas and the incidence of poverty is the highest in the Far western Province where this research was conducted, Therefore, the government, policy makers and other stakeholders should work hand-in-hand to effectively reduce the poverty that persists in Nepal.     

中国电子信息产业创新的集群网络模式与演化路径

流空间背景下,多空间尺度网络耦合对创新至关重要已达成学界共识。综合运用区位熵与社会网络分析,识别32个电子信息产业集群,进而基于1985—2015年合作申请发明专利数据,运用卡方检验和Infomap社区发现算法,借助Pajek和ArcGIS等软件,揭示中国电子信息产业创新合作空间模式,探讨创新网络空间组织演化规律。结果表明：① 中国电子信息产业创新合作呈现集群互联的模式,集群区域的创新主体更倾向于同本地和其他集群区域的创新主体合作,这与非集群区域的创新主体结网方式明显不同,印证了关系经济地理学者提出的全球集群网络论断。② 集群创新网络社区的空间组织从位于集群地理边界内,本地化特征显著,演化为超越集群地理边界,呈现等级差异明显的核心-边缘层级式特征,反映出地理邻近对集群主体创新结网影响程度的动态变化。     

Assessment of Risks Relevant to Underground Measurements for Coal Mining Production and Exploration

Natural Resources Research - In underground mining establishments and in all processes of underground coal mining from investigation activities to production activities, geodetic measurements and...     

Can Hydraulic Conductivity of Fluvial Sediments be Informed by Spectral Reflectance?

Water Resources - This study explores the statistical relationship between spectral reflectance and hydraulic conductivity (K) of fluvial sediments in two Nebraska rivers. The spectral reflectance...