Peatland subsidence and vegetation cover degradation as impacts of the 2015 El niño event revealed by Sentinel-1A SAR data

Indonesia has the world’s largest tropical peatland, mostly located in the southern province of Sumatra, the south of Kalimantan, and Papua. The catastrophic fires between June and October 2015 induced by the El Niño event burnt most of these peatland areas. We analyzed spatio-temporal peat subsidence during pre- and post-fires in the peat hydrological unit of Sungai Sugihan – Sungai Saleh (KHGSS), South Sumatra using Sentinel-1 images by applying DInSAR-SBAS algorithm. Based on our analysis, the linear subsidence rate after the 2015 peat fires increased by a factor 6.4 compared to that of pre-fires. Generally, the estimated subsidence is temporally well-correlated with the precipitation variation. In addition, the subsidence patterns are spatially correlated with the hotspot distribution, peat thickness, and drainage networks. Furthermore, we mapped vegetation cover over the KHGSS by using the Sentinel-1 images as well. The results show that the vegetation degradation is correlated with the hotspot distribution and the highly-degraded vegetation associated with the 2015 peat fires. It demonstrated that the 2015 El Niño event has significant impacts on increasing the amount of the subsidence and the vegetation degradation in KHGSS area.     

火灾中集装箱船剩余极限强度研究

采用ISO规定的火灾的标准温度—时间曲线建立船体结构的火灾模型。基于能量守恒原理建立热传导微分方程,计算热传导、对流和辐射对结构温度分布的影响。考虑火灾发生位置的差异性,分析得到着火区域的温度场。根据高温下钢材的力学性能,针对火灾发生位置的不同,利用非线性有限元方法,分析火灾对集装箱船剩余弯曲极限强度(中拱、中垂)的影响。结果表明,集装箱船不同位置发生火灾时,对船体结构极限强度的影响具有显著差异。船舱某一位置发生火灾时,对船体梁中拱和中垂极限强度的影响也分别不同。对集装箱船火灾的瞬态分析结果表明,火灾对船体梁极限强度的衰减作用主要发生在火灾发展过程中的前期,船体梁极限强度的衰减速度随火灾发展的时间逐渐减慢。     

地质样品中贵金属元素的预处理方法研究进展

本文评述了近年来地质样品中贵金属元素分析预处理技术的研究现状和应用进展,对样品分解过程中常用的火试金法、碱熔融法、酸分解法以及样品分离富集过程中的吸附法、碲共沉淀法、离子交换法、溶剂萃取法、蒸馏法、生物吸附法等手段进行了归纳总结,分析了各方法的特点与不足,展望了技术方法未来发展方向。分解方法中的火试金法经分析工作者不断探索及改进,已成为分解贵金属的最佳手段,但其仍存在试剂消耗量大、成本高、流程长等缺点;碱熔融法虽可分解几乎所有地质样品,但其处理后的溶液存在大量钠盐,需经进一步的纯化;酸分解法主要以高压密闭和卡洛斯管的消解方式为主,但受到样品性质的制约。而不同分离富集的手段都具有较强的针对性,如:吸附法多用于Au、Pt、Pd的富集,蒸馏法仅适用于Os、Ru的分析。由于贵金属元素具有颗粒效应强、赋存形式复杂多样以及超痕量等特殊性,需要针对样品的类型特点选择相适应的预处理方法。本文提出,应当在现有的贵金属分解方法基础上,结合当前新的实验设备及实验条件,寻求更加高效、快捷的分解技术,严格控制流程的本底及各个环节的污染问题,实现多技术、多方法联用,满足贵金属分析的要求。     

新疆SCZ17剖面黑碳记录的16~12 ka火灾历史及其驱动因素探究

基于新疆深390 cm的SCZ17黄土剖面的黑碳(BC)记录以及总有机碳含量(TOC)和磁化率结果,并与巴里坤湖孢粉记录的温度数据对比,重建了该区末次冰消期(16~12 ka,对应剖面深度202~274 cm)的火灾历史并探讨了其控制因素。结果表明:1)在末次冰消期期间黑碳通量与TOC变化具有较好的一致性,均呈上升趋势,说明随着植被量的增加,生物质燃烧活动增加;2)BC通量与湿度和温度数据的EEMD结果显示:①在13~16 ka期间,剖面的黑碳通量指示的区域生物质燃烧变化与温度变化存在着近乎同步的关系,而在12~13 ka期间可能由于湿度的影响二者的同步关系不太明确;②χfd%所指示的湿度变化和黑碳通量的对比结果显示,湿度峰值/谷值分别对应着黑碳通量的谷值/峰值,即当气候湿润时,火灾活动频率低;气候干旱时,火灾活动频率高。因此,认为研究区火灾活动倾向于发生在暖干的气候条件下,且可燃生物量可能控制着区域火灾变化的长期趋势,而由温度和湿度变化所造成的火灾活动的次一级波动叠加在这一长期趋势上。     

Is multi-hazard mapping effective in assessing natural hazards and integrated watershed management?

Natural hazards are often studied in isolation.However,there is a great need to examine hazards holistically to better manage the complex of threats found in any region.Many regions of the world have complex hazard landscapes wherein risk from individual and/or multiple extreme events is omnipresent.Extensive parts of Iran experience a complex array of natural hazards-floods,earthquakes,landslides,forest fires,subsidence,and drought.The effectiveness of risk mitigation is in part a function of whether the complex of hazards can be collectively considered,visualized,and evaluated.This study develops and tests individual and collective multihazard risk maps for floods,landslides,and forest fires to visualize the spatial distribution of risk in Fars Province,southern Iran.To do this,two well-known machine-learning algorithms-SVM and MARS-are used to predict the distribution of these events.Past floods,landslides,and forest fires were surveyed and mapped.The locations of occurrence of these events(individually and collectively) were randomly separated into training(70%) and testing(30%) data sets.The conditioning factors(for floods,landslides,and forest fires) employed to model the risk distributions are aspect,elevation,drainage density,distance from faults,geology,LULC,profile curvature,annual mean rainfall,plan curvature,distance from man-made residential structures,distance from nearest river,distance from nearest road,slope gradient,soil types,mean annual temperature,and TWI.The outputs of the two models were assessed using receiver-operating-characteristic(ROC) curves,true-skill statistics(TSS),and the correlation and deviance values from each models for each hazard.The areas-under-the-curves(AUC) for the MARS model prediction were 76.0%,91.2%,and 90.1% for floods,landslides,and forest fires,respectively.Similarly,the AUCs for the SVM model were 75.5%,89.0%,and 91.5%.The TSS reveals that the MARS model was better able to predict landslide risk,but was less able to predict flood-risk patterns and forest-fire risk.Finally,the combination of flood,forest fire,and landslide risk maps yielded a multi-hazard susceptibility map for the province.The better predictive model indicated that 52.3% of the province was at-risk for at least one of these hazards.This multi-hazard map may yield valuable insight for land-use planning,sustainable development of infrastructure,and also integrated watershed management in Fars Province.     

柴达木盆地北缘湖泊表层沉积物炭屑特征及其环境意义

沉积物中的炭屑在探讨火(灾)的基本特征及其与植被和人类活动关系方面具有重要意义。采用孢粉学提取方法,对柴达木盆地北缘的湖泊表层沉积物进行了微体炭屑的分析工作,用以探讨其空间分布及其与区域植被和现代人类活动之间的关系。结果表明：不同粒径的炭屑浓度均呈现出自西向东升高的趋势,与区域植被覆盖度自西向东增加的趋势一致。其中,小粒径的炭屑以近圆形占多数,表明区域性火事件中燃烧的木本植被占主导地位;粒径较大的长条形炭屑在盆地东部区域占优势,表明地方性火事件向东增加,草本植物燃烧逐渐增多,与自西向东草本植物的增多相吻合,且燃烧由区域向近源转换。此外,该地区人口数量也有自西向东增加的趋势,推测人类生产生活用火对炭屑浓度有很大的贡献量,与大颗粒炭屑浓度向东升高有较好的对应关系。表层沉积物炭屑的空间变化特征不仅很好地反映了相应地区的火的信息,还对区域植被和人类活动等要素具有较好的指示意义。     

Beyond slash-and-burn: The roles of human activities,altered hydrology and fuels in peat fires in Central Kalimantan,Indonesia

Near-annual landscape-scale fires in Indonesia's peatlands have caused severe air pollution, economic losses, and health impacts for millions of Southeast Asia residents. While the extent of fires across the peatland surface has been widely attributed to widespread peatland drainage for plantation agriculture, fires that transition from surface into sub-surface soil-based fires are the source of the most dangerous air pollution. Yet the mechanisms by which this transition occurs have rarely been considered, particularly in diversely managed landscapes. Integrating physical geography methods, including active fire scene evaluations and hydrological monitoring, with qualitative methods such as retrospective fire scene evaluations and semi-structured interviews, this article discusses how and why sub-surface peat fire transition occurs in an intensively altered peatland ecosystem in Indonesia's Central Kalimantan province. We demonstrate that variable water table levels and flammable surface vegetation (fire fuels) are co-produced socio-political and biophysical phenomena that enable the conditions in which surface fire is likely to transition into peat fire and increase landscape vulnerability to ongoing, uncontrollable annual fires. This localized understanding of peat fire transition counters normative causal narratives of tropical fire such as ‘slash-and-burn’, with implications for the management of new fire regimes in inhabited landscapes.     

火灾烟颗粒分形模型和球形模型光散射的比较研究

对烟颗粒的光散射进行模拟计算是研究火灾烟颗粒光散射特性的重要手段,目前对于火灾烟颗粒光散射的数值计算多采用球形或椭球模型.实际上,火灾烟颗粒的形貌与球形和椭球均存在着显著差异.扫描电子显微镜图像表明,烟颗粒具有近似分形的结构.本文利用离散偶极近似方法计算了随机取向的火灾烟颗粒分形凝团以及同体积的球形颗粒的光散射Muller矩阵,并对两者的归一化Muller矩阵元素随散射角的分布进行了比较.研究表明:火灾烟颗粒分形模型和球形模型的归一化矩阵元素F₁₁(θ)/F_{11相似文献}   

天山西部林区护林防火信息系统构建

天山西部林区护林防火信息系统是综合运用空间信息技术、数据库技术及森林防火专业技术,依托地理基础信息、森林资源信息及护林防火专题信息,在Arc GIS Engine开发平台上,通过VB.NET可视化开发语言的二次开发,构建的专业应用系统。该系统的框架包括数据库及林火预测预报、火灾指挥扑救、灾后损失评估、森林资源管理等子系统,可实现火点智能定位、火场信息查询显示、辅助决策指挥等具体功能。为林区护林防火部门进行宏观管理、分析决策提供多源、及时、科学的空间信息服务,旨在改善林区防灾、减灾及森林安全工作的被动局面,提升林火管理的科学化、信息化水平。     

中国东南海域活跃火强度时空动态与发生类型

自然和人为因素引发的植被火是全球生态系统的重要干扰因子,而基于卫星获取的活跃火（active fires）是探究人-火关系与活跃火发生机理、扩展机制的基础。相对于陆域活跃火,海上活跃火发生的时空动态及其强度、类型等研究较为薄弱。基于VIIRS活跃火和海洋地形等数据,通过分析中国东南海域活跃火发生的时间规律、强度特征、地形属性和距海岸线距离等特性,初步确定了海上活跃火类型界定体系。结果表明：(1)本区相同位置活跃火发生具有时序性。2015年前后两年内相同位置活跃火逐渐减少,且低纬地区更突出;而2015年前后三年内低纬地区活跃火发生强度稳定、高纬地区逐渐减少。(2)中国东南海域活跃火呈现明显的空间集-疏特征,即沿岸海域“条带状”聚集区、以曾母暗沙为中心的“团状”聚集区、南海诸岛周围的分散区。(3) 2012—2013年、2015年、2020年活跃火总强度与其月均强度变化一致,即其发生强度增强归因于活跃火的面状、分散发生;2014年、2016—2019年活跃火总强度与月均强度峰值不同步,即其强度增强归因于活跃火的点状、集中发生。(4)基于时空、强度和集聚特征,结合人类活动频繁区布局,将发生时...