Elemental hydrochemistry assessment on its variation and quality status in Langat River, Western Peninsular Malaysia

This paper discusses the hydrochemistry variation and its quality status in Langat River, based on the chemistry of major ions, metal concentrations and suitability for drinking purposes. Water samples were collected from 30 different stations to assess their hydrochemical characteristics. The physico-chemical parameters selected were temperature, electrical conductivity, total dissolved solids (TDS), salinity, dissolved oxygen , pH, redox potential, HCO₃, Cl, SO₄, NO₃, Ca, Na, K, Mg, ²⁷Al, ¹³⁸Ba, ⁹Be, ¹¹¹Cd, ⁵⁹Co, ⁶³Cu, ⁵²Cr, ⁵⁷Fe, ⁵⁵Mn, ⁶⁰Ni, ²⁰⁸Pb, ⁸⁰Se and ⁶⁶Zn to investigate the variation of the constituents in the river water. Most of the parameters comply with the Drinking Water Quality Standard of the World Health Organization and the Malaysian National Standard for Drinking Water Quality by the Malaysia Ministry of Health except for EC, TDS, Cl, HCO₃, SO₄, Na, Mg, Al, Fe and Se. The results show that the Langat River is unsuitable for drinking purposes directly without treatment.     

Biodiversity and biomass of a natural and degraded mangrove forest of Peninsular Malaysia

Anthropogenic activities have always been the cause of most environmental degradation, and mangrove disappearance is no exception. A comparative assessment on the biodiversity of natural and degraded mangrove forests has been undertaken, looking at the biomass, both above-ground and below-ground. The natural and the degraded mangrove forests were situated at Kuala Selangor and Sungai Haji Dorani, respectively, both on the West coast of Peninsular Malaysia. A random sample scheme with quadrate sample plots (10 m × 10 m) was adopted for the measurement of the diameter at breast height and total height of individual tree species at both forests. Diversity indices and above- and below-ground biomass were estimated from this inventory. Eight mangrove tree species were identified at both study areas, namely: Bruguiera parviflora, Avicennia officinalis, Rhizophora mucronata, Sonneratia alba, Avicennia marina, Bruguiera cylindrica, Xylocarpus mekongensis and Excoecaria agallocha. The mangrove species in Sungai Haji Dorani showed high diversity with a Shannon–Weiner Index (H′) value of 0.91, compared to the natural mangrove of Kuala Selangor which has a lower value, H′ = 0.55. The dominant species in the natural mangrove area was B. parviflora, with the highest Important Value Index (IVI) of 70.96 %, as opposed to A. marina which was the most common species in the degraded mangrove area, with IVI of 49.16 %. An estimate of 305.46 t/ha of above-ground biomass was calculated for the natural mangrove, while 122.78 t/ha was obtained for the degraded mangrove forest. This contrasts with the below-ground biomass estimates, which were 14.09 t/ha for the natural mangrove and 36.35 t/ha for the degraded mangrove.     

河南省嵩县地质灾害风险评价

基于ArcGIS环境下,通过选取河南省嵩县区域高程、地貌、工程岩组、植被覆盖度、距构造距离、距水系距离、坡度、坡向等 8个因子建立危险性评价模型,易损性选取建筑物、人员和交通等 3 个承灾因子,分别采用信息量模型和层次分析法对河南省嵩县区域进行地质灾害易发性、危险性和易损性评价。研究结果表明,嵩县区域划分为低风险区面积为965.34 km2,占嵩县区域面积32%;中风险区面积为1114.65 km2,占嵩县区域面积的37%;高风险区面积为826.23 km2,占嵩县区域面积的27%;极高风险区面积为102.68 km2,占嵩县区域面积的3%。研究成果可应用于嵩县防灾减灾及地质灾害风险管控等方面。     

四川康定城地质灾害危险性分区评价

以康定城为例,提出了城市地质灾害危险性分区评价的新方法,建立了地质灾害易发性和地质灾害社会经济易损性评价因子指标体系与评价方法,在地质灾害易发性和易损性评价基础上,进行地质灾害危险性分区评价。其危险性等级划分标准与国务院地质灾害防治条例和突发地质灾害应急预案函中的划分标准一致,评价结果可直接用于城市地质灾害防治规划编制工作,为城市防灾减灾和实施地质灾害避让搬迁、监测报警和防治工程的实施提供了科学依据。     

地质灾害危险性评价研究——以四川省青川县为例

我国是一个地质灾害多发的国家。20世纪90年中期,每年造成1000多人死亡,经济损失高达200多亿元。地质灾害危险性评价是地质灾害调查的重要内容,也是风险管理及减灾管理的基础,它为管理部门制定出相应的减灾对策并为部署实施有效的减灾工程提供了科学依据。文章首先介绍了国内外地质灾害危险性评价方法的研究现状,通过对比,指出现阶段我国地质灾害危险性评价中的不足;结合实际工作经验,运用危险性评价指标对比法建立了简单有效的地质灾害危险性评价体系。以四川省青川县地质灾害调查为例,对该县地质灾害进行了危险性评价,为地质灾害易发区划分及防治分区提供了依据。     

安徽黄山市徽州区地质灾害危险性评价研究

皖南山区是安徽省地质灾害高发区域。本文选取黄山市徽州区为研究区,根据区内地形地貌和地质构造特点,选取了高程、坡度、坡向、断裂构造、水系、土地覆盖类型、工程地质岩组、人类活动强度等8项致灾因子作为地质灾害危险性评价指标。结合地质灾害野外实地调查成果,采用信息量模型法对研究区进行地质灾害危险性评价,探索建立适合皖南山区的地质灾害危险性评价模型。     

鄂西远安县地质灾害发育特征与形成条件分析

在对远安县地质灾害进行详细调查的基础上,通过成果资料数据统计,梳理出研究区地质灾害数量、类型、规模等发育特征,同时对其时空分布特征和形成条件进行系统分析.研究表明,该县地质灾害具有爆发频率高、突发性强、危害大、隐蔽性强的特点.地灾灾害分布发育与地貌有密切的关系,滑坡灾害主要分布于县域东部的低山丘陵区,崩塌灾害主要分布于县域西部的中低山区,县域中部的冲积平原区地质灾害不发育;时间上,地质灾害多集中发生雨季.区内地质灾害形成的内在因素为地形地貌、地层岩性和地质构造,外在因素为降雨和人类工程活动.     

Groundwater resources assessment using integrated geophysical techniques in the southwestern region of Peninsular Malaysia

Combined geophysical techniques such as multi-electrode resistivity, induced polarization, and borehole geophysical techniques were carried out on volcano-sedimentary rocks in the north of Gemas as part of the groundwater resource’s investigations. The result identifies four resistivity units: the tuffaceous mudstone, tuffaceous sandstone, the tuff bed, and the shale layer. Two types of aquifer systems in terms of storage were identified within the area: one within a fracture system (tuff), which is the leaky area through which vertical flow of groundwater occurs, and an intergranular property of the sandy material of the aquifer which includes sandstone and tuffaceous sandstone. The result also reveals that the aquifer occupies a surface area of about 3,250,555 m² with a mean depth of 43.71 m and a net volume of 9.798?×?10⁷?m³. From the approximate volume of the porous zone (28 %) and the total aquifer volume, a usable capacity of (274.339?±?30.177)?×?10⁷?m³ of water in the study area can be deduced. This study provides useful information that can be used to develop a much broader understanding of the nature of groundwater potential in the area and their relationship with the local geology.     

Heavy metal contents in soil of major towns in the east coast of Peninsular Malaysia

A total of 63 soil samples from 3 different soil profiles （urban, suburban and industrial areas） in major towns in the east coast of Peninsular Malaysia were analyzed for the total concentrations of Cu, Zn, Pb, Ni and Cr. The soil samples were subjected to acid digestion and the concentrations of total metals extracted were measured or flame atomic absorption spectrometry and inductively coupled plasma - atomic emission spectrometry. According to the result of this study, Pb and Zn concentrations in urban soils are much higher than those of industrial and suburban soils. Total concentrations of Cu and Cr in industrial soil samples are high compared to other two soil profiles and Ni concentrations in the suburban area are slightly higher those of urban and industrial soils. Since Malaysia has not yet to come up with her own soil maximum allowable limit, the heavy metal concentrations were compared with the Dutch maximum allowable limit. The results indicated that the median of heavy metals values in the three different soil profiles is still below the Dutch system limit. From the maximum allowable value obtained from the Dutch system, a contamination/pollution （C/p） index for each site was calculated for the set of these five heavy metals. An advantage of using this method is to make a differentiation between pollution （C/p〉1） and contamination （C/p〈1） status in soils as well as being able to characterize each status into 5 different categories （slight, moderate, severe, very severe and excessive）.     

巫山县新城区主要衍生地质灾害调查与评价

三峡水库区自然地质灾害调查和研究已广为报道。但对衍生地质灾害调查研究涉及甚少。三峡移民迁建的县城、乡镇和工厂多位于长江沿岸低山斜坡地带，迁建区内沟谷密布、切割强烈、地形复杂，几乎无可供成片建设的平坦地带。为满足移民工程的需求，迁建业主都采用“削坡填沟”的施工方式，即在道路、迁建场地内侧开挖高边坡，外侧修建挡土墙，并将开挖的弃土弃渣堆积于挡土墙内或冲沟中。这在道路、迁建场地两侧形成了众多的人工高边坡、高挡墙，沿冲沟堆放了成串的弃土弃渣。对巫山县新城区详细的衍生地质灾害调查表明，三峡移民迁建工程施工中开挖的高边坡、修建的挡土墙和沿冲沟堆放的弃土弃渣都不同程度地破坏了天然山坡的稳定性，堵塞了地表迳流的排泄途径，在某些地段存在发生崩塌、滑坡、泥石流等衍生地质灾害的内在因素．直接威胁移民建设工程。论文以巫山县新城区为重点，采用遥感调查与地面调查相结合的方法对人工高边坡、高挡墙和弃土弃渣堆放场进行调查评价。经调查共计人工高边坡、高挡墙、弃土弃渣堆放场122个，选定了重点监测对象20个，并对可能发生衍生地质灾害的3个地段进行了分析，为各级移民管理部门进行适时管理和决策提供现时性强、数据准确的资料。     

甘肃定西地区地质灾害危险性评价

识别地质灾害聚集的热点区及驱动力对于区域灾害预警具有重要意义。以甘肃定西地区为研究区,选取坡度、坡向、土地利用等7个评价因子,利用确定系数与逻辑回归耦合模型、空间自相关方法分析地质灾害的空间集聚特征及驱动因素。结果表明：定西地区地质灾害危险性呈现中部高,南北两侧低的特征,其主要受降水、坡向、工程岩组等因子的影响;地质灾害与降水、坡向和工程岩组的空间关系为高高聚集;地质灾害危险性存在较强的空间自相关性,在3 km的空间尺度上呈显著正相关,且随距离阈值增加而降低;距离阈值为5 km时,正相关高高聚集与低低聚集以团块的形式存在,而高低聚集与低高聚集多以零星状分布。研究可为区域地质灾害监测与防控提供参考。     

关于地质灾害孕灾因子权重确定的探讨

地质灾害易发区划模型中,不同地区孕灾因子权重不同。因子权重的确定、求解权重的准确性将直接关系到区划结果的可靠度。本文根据地质灾害点在不同孕灾因子分区中的分布频率,推出不同孕灾因子对地质灾害发育的贡献率的相对大小。不同因子对地质灾害发育的贡献率实际上就是各因子在地质灾害易发模型中的权重,因此通过以上分析可得出不同孕灾因子的相对权重,再利用层次分析法(AHP法)得出孕灾因子的权重。通过统计分析得出各因子相对权重的方法弥补了层次分析法确定权重的人为随意性,提高了区划的准确度。     

The socioeconomic impact of climate-related hazards: flash flood impact assessment in Kuala Lumpur,Malaysia

Small-scale flash flood events are climate-related disasters which can put multiple aspects of the system at risk. The consequences of flash floods in densely populated cities are increasingly becoming problematic around the globe. However, they are largely ignored in disaster impact assessment studies, especially in assessing socioeconomic loss and damage, which can provide a significant insight for disaster risk reduction measures. Using a structured questionnaire survey, this study applied a statistical approach and developed a structural equation model (SEM) for assessing several socioeconomic dimensions including physical impacts, mobility disruption, lifeline facilities, health and income-related impacts. The study reveals that respondents have experienced a stronger impact on direct tangible elements such as household contents and buildings as well as direct intangible elements with β coefficients 0.703, 0.576 and 0.635, respectively, at p?<?0:001 level. The direct intangible impacts affect mobility disruption with β coefficients equal to 0.701 at p?<?0:001 level which then further cause adversity to income-generating activities with β 0.316 at significant p?<?0:001 as well. The overall model fit indices show highly acceptable scores of SRMR 0.068, RMSEA 0.055 and PClose 0.092. Thus, the SEM has successfully incorporated the socioeconomic dimensions of disaster impact and explained the impact phenomena reliably. This modeling approach will allow inclusion of various variables from different disciplines to assess hazard impact, vulnerability and resilience.

     

The use of the natural gamma log in engineering geological investigations

The natural gamma log is widely used in both cased and uncased boreholes to identify changes in lithology down the length of a borehole. This is particularly important in the ground investigation process where 100% core recovery is often not achieved in the borehole programme. In this paper the use of the gamma log to provide additional information from the ground investigation boreholes is examined and illustrated by a number of case histories. It is shown that the gamma log can be used to study both the lithological variations within an individual borehole and changes in geological structure across a construction site. It is also demonstrated that a geological formation or sequence can be classified in terms of its natural gamma signature, which enables the geologist to observe its presence over large distances on a regional basis. The importance of the calibration of the gamma sonde and the use of the correct logging speed is emphasised in the paper. The successful calibration of the log against a quarry wall using a known observed geological structure as a reference is also described together with the use of the resulting information to obtain a geological log for boreholes drilled behind the quarry face. Its use in extrapolating between boreholes to detect and trace the presence of a particular geological formation to estimate its vertical and lateral extent for possible extraction is also discussed.     

陕西省地质灾害易发性综合评价方法初探

陕西省的地质灾害主要包括滑坡、崩塌、泥石流、地面塌陷、地裂缝及地面沉降。论文在总结陕西省107个县（市）地质灾害调查与区划工作的基础上,建立了陕西省地质灾害易发性综合评价指标体系。针对不同灾种选择了25个评价指标作为其易发性的主要影响因素。使用专家——AHP定权法确定各影响因素的权重,并基于GIS构建了综合评价数学模型——综合指数模型,将各指标因子图层按权重进行代数叠加运算,计算出全省地质灾害易发性综合指数。然后根据综合指数的大小,将陕西省地质灾害易发程度划分为高易发、中易发、低易发和非易发四级区。     

Probabilistic landslide hazards and risk mapping on Penang Island, Malaysia

This paper deals with landslide hazards and risk analysis of Penang Island, Malaysia using Geographic Information System (GIS) and remote sensing data. Landslide locations in the study area were identified from interpretations of aerial photographs and field surveys. Topographical/geological data and satellite images were collected and processed using GIS and image processing tools. There are ten landslide inducing parameters which are considered for landslide hazard analysis. These parameters are topographic slope, aspect, curvature and distance from drainage, all derived from the topographic database; geology and distance from lineament, derived from the geologic database; landuse from Landsat satellite images; soil from the soil database; precipitation amount, derived from the rainfall database; and the vegetation index value from SPOT satellite images. Landslide susceptibility was analyzed using landslide-occurrence factors employing the probability-frequency ratio model. The results of the analysis were verified using the landslide location data and compared with the probabilistic model. The accuracy observed was 80.03%. The qualitative landslide hazard analysis was carried out using the frequency ratio model through the map overlay analysis in GIS environment. The accuracy of hazard map was 86.41%. Further, risk analysis was done by studying the landslide hazard map and damageable objects at risk. This information could be used to estimate the risk to population, property and existing infrastructure like transportation network.     

徽(州)-杭(州)高速公路(安徽段)地质灾害遥感调查与评价

徽-杭高速公路(安徽段)位于皖南山区腹地、地形地貌复杂，构造发育，是地质灾害多发地区。利用航卫片解译结合野外调查，在高速公路预选线共圈定出大小滑坡和崩塌252处，这些滑坡与崩塌多分布在新安江及其支流凹岸一侧或河流岸坡与沟谷切割且临空条件较好的斜坡地带，以及徽-杭老公路切坡地段。根据本次遥感调查提出①大阜南侧滑坡；①霞井西北段；③荷花形292高地滑坡群的预选线路应作调整；④榧树NFDA2滑坡体上的公路预选线应改线另选新线。同时对雄村、尼姑庵、朱村、竹岭脚等处的滑坡需要进行勘察后，再提出有效的防治方案。