曼谷地区干旱灾害风险分布及变化趋势分析

基于自然灾害风险评估理论,依据致灾因子危险性、承灾体的脆弱性,综合评估曼谷节点地区的干旱灾害风险。进而分析2000—2020年曼谷干旱灾害危险性、脆弱性和风险的空间分布特征和变化趋势。结果表明:1)曼谷干旱危险性在地区间存在差异,符合“北高南低”的规律。高脆弱性地区集中在曼谷都市区中部、佛统府西北部和沙没巴干府西部,与自然条件、人口和经济分布以及城市活动有关。曼谷干旱风险较高,中等及以上干旱灾害风险土地占总面积的41.64%,佛统府西北部和巴吞他尼府中部具有最高风险,同时具有较高的脆弱性和危险性。2)曼谷的风险性、脆弱性和危险性均呈线性上升趋势。巴吞他尼府和佛统府的危险性,佛统府西北部和曼谷中部城乡居民用地的脆弱性,以及佛统府西北部和、巴吞他尼府中部和曼谷都市区中部的干旱风险程度上升较快。3)M-K检验结果显示,曼谷危险性和风险均呈现“东升西降”的空间分布特征,但变化趋势均不显著。曼谷的脆弱性在大部分地区呈极显著上升趋势,沙没沙空府的脆弱性上升趋势最为显著,达到71.23%。4)曼谷的干旱灾害风险程度由危险性和脆弱性共同决定,一元线性线性回归分析结果与M-K检验分析结果在空间分布上存在明显差异,但都表明需采取措施降低脆弱性以降低城市干旱灾害风险。利用精细尺度的空间数据进行分析可以更准确反映该地区的资源管理能力,提高风险评估的合理性,为节点城市的灾害风险管理和风险分布研究提供有价值的参考。

喀斯特山区土壤侵蚀强度空间分布与风险评价——以贵州省绥阳县为例

为探究喀斯特山区土壤侵蚀空间分布特征,进一步探索解决土壤侵蚀造成的土地资源破坏、土壤肥力损失、质地恶化以及石漠化加剧等问题,以贵州省典型喀斯特山区绥阳县为研究区,选取ALOS影像、DEM和社会经济数据,运用人机交互解译方法提取坡度、土地利用及植被覆盖度等指标因子,以GIS空间分析探索土壤侵蚀强度的指标因子相关性、空间特征和风险性评价。结果表明:1)该研究区土壤侵蚀强度的等级面积比依次为:中度(32.35%)>强度(24.55%)>微度(21.28%)>较强度(9.28%)>轻度(6.66%)>剧烈(5.88%),中度侵蚀类型和强度侵蚀类型占主导部分;2)土壤侵蚀强度与坡度的相关系数为0.670,与植被覆盖度的相关系数为0.386,具有显著的正相关关系;3)研究区SEDI指数为423,土壤侵蚀程度达到较重等级,存在较强的潜在风险。其中,研究区东北部、东南部、东部等地SEDI指数最高,绥阳县西南部风华镇一带SEDI指数最低。该研究为预防喀斯特山区土壤退化、改善土壤环境及生态建设具有一定参考意义。

基于空间模糊层次分析的航行环境风险评估

随着海上交通日益繁忙,保障船舶安全航行成为全球性重要议题。本文从航行自然环境和海上交通环境两方面构建航行环境风险评估模型,将地理空间技术和模糊层次分析法(fuzzy analytic hierarchy process,FAHP)结合,对厦门港及其周边海域的航行环境风险评估,形成风险分级图并对其空间分布特征进行分析。结果表明:受自然环境影响,该区域航行环境风险大致呈“U”型分布,风险等级沿“SW—NE”逐渐降低;在交通环境影响下,风险等级≥8级的区域呈散点状分布在距海岸线较远海域,尤其是兄弟屿东部海域;综合以上两方面,厦门港及其周边海域航行环境风险整体处于中等偏低风险,但仍有约6.17%的区域风险等级≥7级,主要分布在“南澎列岛—兄弟屿”连线的延长线以南和厦门湾海域。

基于故障树分析的中国道路风险分布规律研究

以道路因素为牵引,并耦合驾驶人因素和车辆因素把道路因素事故作为顶上事件,确定道路线形因素事故、道路路面因素事故、路口路段因素事故为中间事件,构建了道路因素事故分析故障树模型。对数据归一化后,进行了道路因素事故分析故障树模型求解,得出了中国道路典型危险场景。并进一步建立了每个典型风险场景的子故障树。因控制概率重要度大的基本事件的发生,能使顶上事件发生的概率迅速降低,故通过对子故障树求解概率重要度,得出了关键影响因素,最终揭示了道路安全风险的空间分布规律。

Spatial Distribution and Risk Assessment of Heavy Metals in Paddy Soils of Yongshuyu Irrigation Area from Songhua River Basin,Northeast China

There is an increasing concern for potentially hazardous metals pollution, which can threaten crops production and human health. In this study, the spatial distribution and environmental risks of eight heavy metals in surface soil samples collected from the paddy fields in Yongshuyu irrigation area, Northeast China were investigated. The mean concentrations of Pb, Cr, Cu, Ni, Zn, Cd, Hg and As were 34.6 ± 4.67, 82.8 ± 9.51, 17.3 ± 4.09, 21.2 ± 12.0, 88.6 ± 17.9, 0.18 ± 0.15, 0.22 ± 0.07 and 8.77 ± 2.47 mg/kg, respectively, which were slightly higher than their corresponding background values of Jilin Province, indicating enrichment of these metals in the paddy soils, especially for Ni, Cd and Hg. The spatial distribution of heavy metals was closely correlated with local anthropogenic activities, such as agricultural production, mining and transportation. The hot-spot areas of As and Cd were mainly concentrated in the up-midstream where were associated with agricultural activities. Cr and Cu showed similar spatial distributions with hot-spot areas distributed the whole irrigation area uniformly. Ni was mainly distributed in the downstream where Ni quarries concentrated, while the spatial distribution patterns of Hg was mainly located in the upstream and downstream where the soil was significantly influenced by irrigation and coal mining emission. The spatial distributions of Pb and Zn were mainly concentrated along the highway side. The pollution levels of Yongshuyu irrigation area were estimated through index of geo-accumulation(Igeo), Nemerow integrated pollution index(NIPI) and potential ecological risk index(PERI). The results showed that Cd and Hg were the main pollutants in the study area. Health risk assessment results indicated that children were in higher non-carcinogenic and carcinogenic risks than adults with the carcinogenic metal of As. Ingestion was the main exposure pathway to non-carcinogenic and carcinogenic risk for both adults and children. Principal component analysis(PCA) indicated that Cr and Cu were mainly from parent materials, while Cd and As were mainly affected by agricultural activities. Pb and Zn were controlled by traffic activities, and the accumulations of Ni and Hg were associated with mining activities. This study would be valuable for preventing heavy metals inputs and safety in rice production of the Songhua river basin.

Spatial distribution,sources and ecological risk assessment of heavy metals in Shenjia River watershed of the Three Gorges Reservoir Area

Surface soil/sediment samples were collected from the Water-Level Fluctuation Zone(WLFZ), cultivated land and forest land at 50 different grid points from Shenjia watershed, the Three Gorges Reservoir area in August 2013. The spatial distribution, sources and ecological risk assessment for Arsenic(As), Cadmium(Cd),Chromium(Cr), Copper(Cu), Nickel(Ni), Lead(Pb)and Zinc(Zn) were analyzed in this study. The results showed all tested metals had similar distribution patterns except Ni and Cr, with areas of high concentrations distributed in the southwest(WLFZ and watershed outlet) of the study area. Ni and Cr,which were highly positively correlated and present in high concentrations, were primarily distributed in the south and middle zones of the study area. Lower concentration areas of all metals were uniformly distributed west of the high-elevation zones and forest land. Factor analysis(FA) and factor analysismultiple linear regression(FA-MLR) showed that the major sources of Cd were fertilizer and traffic sources,which together accounted for 87% of Cd. As, Zn and Cu levels were primarily supplied by industrial and domestic sources, accounting for 76% of As, 75% of Cu and 67% of Zn. Surface soils/sediments of the study watershed contaminated by Cd represent a high ecological risk, whereas other metals represent low ecological risks. The potential ecological risk index(PERI) analysis indicated that it had a low(widerange) ecological risk and a moderate(small-range)ecological risk primarily distributed in the outlet of the study watershed. Fertilizers and traffic are the primary sources of Cd pollution, which should be more closely controlled for the purposes of water quality and ecological conservation.

Trace elements spatial distribution characteristics,risk assessment and potential source identification in surface water from Honghu Lake,China

Five trace elements including Zn, Cu, Cd, Cr and As were investigated in surface water from ten typical sampling sites in Honghu Lake. The consequence indicated that all of the detected trace element levels were within the allowed standard of China’s safe water guideline. The hazard quotients （HQ） and the hazard index （HI） value levels of all the five heavy metals in all sampling sites did not exceed the acceptable risk limits of non-carcinogenic value through the selected assessment method. Pearson’s correlation analysis and principal component analysis （PCA） indicated that Zn and Cu mainly originated from the natural alluviation and non-point agricultural sources, whereas Cr and As were mainly derived from industrial effluents. Moreover, Cd mainly originated from both non-point agricultural and industrial pollution sources. In addition, cluster analysis （CA） implied that cluster 1 （including S3, S5, S6 and S10） was considered the set of high pollution sites and cluster 2 （including S4 and S9） was identified as the set of moderate pollution sites.

The distribution and potential ecological risk of Pb for multi-phase medium of artificial reefs in summer

Using inductively coupled plasma mass spectrometry(ICP-MS)to detect the Pb content in the multi-phase medium(water,sediment and large benthic organisms)in the artificial reef areas of Bohai Bay in Tianjin to analysis its spatial distribution characteristics and potential ecological risk.Using different evaluation methods.The results showed that:the Pb content is varied from 0.003-0.024μg/L,mean 0.008±0.007μg/L,the highest values appear in the No.9 station;the minimum value is 5 stations.Pb content of sediment is varied from 0.003-0.024μg/L,mean 0.008±0.007μg/L,the highest values appear in the No.9 station;the minimum value is 5 stations.The vertical sediment distribution of Pb decreased in the order:lower>middle>upper layer in each station.Risk evaluation showed that potential ecological risk index of Pb is low in the reef sediments;accumulate partial index is belong to moderate pollution levels;enrichment factor is belong to the light^pollution-free.Pb content of organisms is rang from 0.004-0.519 mg/kg,mean 0.185±0.170 mg/kg in reef area;BCF value of Pb content in organisms is generally higher than BAF value;its health risk factor is far less than 1,indicating that Pb has no obvious health risks on exposure population.

Study on Potential Strong Earthquake Risks Around the Mabian Area,Southern Sichuan

Based on seismic data from the regional network for the last 34 years, we analyzed the present fault behavior of major fault zones around the Mabian area, southern Sichuan, and identified the risky fault-segments for potential future. The method of analysis is a combination of activity background of historical strong earthquakes mainly show ~ （ 1 ） The spatial distribution of b-values strong and large earthquakes in the spatial distribution of b-values with and current seismicity. Our results indicates significant heterogeneity in the studied area, which reflects the spatial difference of cumulative stress levels along various fault zones and segments. （2） Three anomalously low b-value areas with different dimensions were identified along the Mabian-Yanjin fault zone. These anomalies can be asperities under relatively high cumulated stress levels. Two asperities are located in the north of Mabian county, in Lidian town in western Muchuan county, and near Yanjin at the south end of the fault zone. These two areas represent potential large earthquake seismogenic sites around the Mabian area in the near future. Besides them, the third relatively smaller asperity is identified at southern Suijiang, as another potential strong- earthquake source. （3） An asperity along the southwestern segment of the Longquanshan fault zone indicates the site of potential moderate-to-strong earthquakes. （4） The asperity along the segment between Huangmu town in Hanyuan county and Longchi town in Emeishan city on Jinkouhe-Meigu fault has potential for a moderate-strong earthquake.