Highways protection from flood hazards,a case study: New Tama road,KSA

Natural Hazards - Highways in arid regions are highly exposed to damage by floods. This requires intensive analysis of flood quantity, time and direction that can be used to design the suitable...     

约旦南部瓦迪巴希亚地区铀矿化地球物理特征

通过对瓦迪巴希亚（Wadi Bahiya）地区开展地质调查、岩石取样分析以及地面γ能谱测量等综合研究,认为研究区铀矿化主要产于上白垩统—古新统MCM组近地表风化破碎的灰褐色砂土状泥灰岩之中,矿化类型为现代氧化作用成因的钙结岩型,研究区γ能谱测量铀质量分数平面特征表现为异常规模小,晕圈梯度变化大,深部揭露表明,自近地表向深部铀质量分数逐渐降低,岩石取样分析结果与γ能谱测量具有对应性,铀矿化主要位于地表以下0.5～1.5m的范围内。     

Risk evaluation of geological hazards of mountainous tourist area: a case study of Mengshan,China

Natural Hazards - Risk evaluation is crucial for the construction projects in the areas with high risk of geological hazards. In this paper, based on the projects of Mengshan tourism area,...     

南方山地丘陵区地质灾害调查工程主要进展与成果

我国南方山地丘陵区地质灾害分布数量约占全国地质灾害总数的57%,复杂的孕灾地质背景条件和诱发因素在很大程度上制约了地方政府对地质灾害的早期识别及监测预警能力,从而对各地国家基础设施和人民生命财产安全以及重大战略工程的实施造成影响,因此,提升对南方山地丘陵区地质灾害发育分布规律的认识和防治水平就显得极为重要和迫切。为满足服务国家重大战略实施的防灾减灾需求,中国地质调查局部署了“南方山地丘陵区地质灾害调查工程”,以支撑服务国家和地方防灾减灾需求为导向,以“出技术、出方法、出规范”为目标,采用“空-天-地”一体化调查技术,重点围绕地质灾害的早期识别、监测预警、风险评价及防灾减灾方法等开展调查研究与应用示范,引领和指导南方山地丘陵区的地质灾害调查。该工程通过2019年的调查研究,对南方山地丘陵区地质灾害发育的总体分布规律、危害程度及成因机制有了宏观认识,为区域地质灾害研究与评价提供了重要基础。取得的地质灾害调查成果为国家一系列重大战略工程的规划建设提供了有效服务。如在川藏铁路建设工程中,为某车站选址提供了地质综合评估建议,成功识别出的潜在滑坡隐患为某特大桥梁设计方案变更提供了重要的地质依据; 服务于乌蒙山区及赣州地区地质灾害自动化监测预警系统建设,有效提升了地方政府防灾减灾的效率与水平; 及时配合自然资源部金沙江白格滑坡、宜宾地震、浙江永嘉滑坡等重大突发性地质灾害的应急抢险工作,并提供了有效的技术支持; 在汛期为四川省和云南省等地方政府开展地质灾害应急排查20余次,为这些地区的安全度汛发挥了重要作用; 积极开展多种形式的地质灾害科学普及活动,提高了广大民众的地质灾害防治知识水平。     

Delineation of saline groundwater and sea water intrusion zones using transient electromagnetic (TEM) method, Wadi Thuwal area, Saudi Arabia

In the coastal western part of Saudi Arabia at Thuwal area located close from the Red Sea, the shallow groundwater specific electrical conductivities measured at the drill holes range from 6 to 13 mS/cm. In order to study the origin of this salinity, a good knowledge is required of the aquifer geometry with depth. Ninety nine transient electromagnetic (TEM) soundings were carried out over an area of about 100 km². From the TEM profiles, a conductive substratum with a resistivity of 1–13 Ωm was identified at most of the sites at depth ranging from 50 to 150 m. This substratum is related to Oligocene–Miocene sediments (Shumaysi Formation) which are mainly red clay-rich formation containing brines at coastal zones. Clayey sediments are more likely present in the southeastern part and along the faults that run NE–SW across the study area and parallel to the Quaternary volcanic which runs NW–SE. The study demonstrated the effectiveness of the TEM sounding method to map conductive zones.     

Reconnaissance geochemical survey in the Marahiq area,Wadi Allaqi region,south Egypt: a preliminary assessment of stream sediments for gold placer and environmental hazard

The Marahiq area represents a portion of the Pan-African belt from the Neoproterozoic age in south Egypt and includes metamorphosed ultramafic rocks, metavolcanic rocks, and granodiorite pluton. The area is characterized by the ancient abandoned Au mine and the recent active talc mines. The present paper provides a preliminary assessment of stream sediments for gold (Au) placer and environmental hazard. Steam sediments from 36 stations were analyzed using ICP-MS for determining the concentration of 53 elements. Various statistical techniques, graphical representations, a set of complementary sediment quality assessment methods, and different mapping methods have been applied. The results showed that Au and the investigated elements were influenced by long history of the ancient mining activities and weathering processes, leading to elevate Au and some heavy metal(loid)s concentrations and exhibit enrichment ratios as follows: Te > As > Au > Cu > Cd > Co > Ni > V. Whereas Cd, Co, and V were attributed to geogenic origin, As, Au, Cu, Ni, and Te were derived from anthropogenic mining activities. It is found that the anomalies of Au and the element of interest are indicative of Au placer and point out a new perspective Au-sulfide mineralization hosted along the favorable tectonic zones that were the main source of Au placer. Both As and Te are good pathfinders to explore Au placer and related mineralization. Environmentally, the excess of As, Cu, Ni, and Te could generate moderate levels of contamination and low level of ecological risk in the sediments. Although As, Cu and Ni posed medium–low potentially adverse effects and low toxicity levels, they cannot cause harmful influences on biological life. Accordingly, streambed sediments are considered as safe and acceptable as inoffensive materials for environmental management. Overall, this study is as reference values for governmental organizations for appraising future environmental pollution in the area. Also, it is fruitful for Au placer and promising with success for Au exploration along the shear zones and strike-slip faults.     

A geological excursion in the Wadi Fatima area, near Jiddah, Saudi Arabia

Wadi Fatima, east of jiddah on the Red Sea coast of Saudi Arabia, is a microcosm of the geology of the jiddah area. Rocks ranging in age from 800-million-year-old metamorphic rocks to Tertiary lava flows are exposed, and illustrate the geological richness of western Saudi Arabia. The valley is a major south-west-trending fault zone that has been active since Precambrian times. A major Tertiary dyke swarm in the vicinity of Wadi Fatima is related to the opening of the Red Sea as the African-Arabian landmass split apart.     

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。     

Coupling of remote sensing data aided with field investigations for geological hazards assessment in Jazan area,Kingdom of Saudi Arabia

The city of Jazan is situated on the eastern flank of the Read Sea and considered as one of the fastest growing cities in the Kingdom of Saudi Arabia. This zone attracts a lot of investors for various development projects. Recently, many new projects have been implemented and constructed in this region including new urban areas, infrastructures, and industrial projects. However, historically this area has been challenged from different types of geological hazards. These geological hazards are catastrophic events that can cause human injury, loss of life, and economic devastation. The current study is aimed at evaluating the different types of geological hazards in Jazan city. This study is based on interpretation of satellite data such as LANDSAT and QuickBird images, existing geological maps, and physiographical characteristics with the help of field and laboratory analyses. The results of the analysis indicate that there exist various types of geological hazards in the study area mostly related to the natural factors which include (1) Sabkha soil; (2) Salt dome; (3) Loess soil; and (4) Sand dune/drift. Further, the findings of this study revealed that, most of these geological hazards have a severe impact on the ongoing development activities in Jazan area.     

地震滑坡危险性评价及编图——以映秀震中区为例

虽然宣称地球已进入地震多发期目前学术界还存在不少争议,但不得不承认近期的破坏性强震发生的频率较以往高.强震诱发的滑坡灾害也越来越成为了地质学家们研究的热点.在对一个地区发出中长期地震预报之后,如果也能相应地对该地区的斜坡稳定性进行评价,从而预测地震时滑坡最可能发生的地段,这对于减轻震区人民的伤亡和财产损失将具有重要的意义.本文对目前常用的地震滑坡危险性评价方法进行了简要介绍,并以“5.12”汶川地震映秀震中区为例,运用Newmark方法对该区进行了地震滑坡危险性评价和编图示范,探讨了目前常用地震滑坡危险性评价方法的优缺点及今后区域性地震滑坡危险性评价的发展方向.     

复杂地区三维区域地质调查流程:本溪—临江地区为例

在变质变形复杂的辽宁东部—吉林南部的本溪—临江地区开展的三维地质调查工作的基础上,经反复探索实践,得出了由区域主干剖面、区域建模剖面、建模约束剖面和建模剖面四级剖面控制下的分单元三维地质调查方法可以有效约束地下深部地质结构;提出了开展三维区域地质调查的17个步骤;讨论了方法与流程在本溪—临江地区的应用情况、有效性、可操作性及可靠性。     

Groundwater resources assessment for irrigable agricultural lands in the Wadi Araba area, southern Jordan

The main target of this research paper was to the hydrogeological assessment of the groundwater resources to irrigate 600 ha of irrigable agricultural lands, distributed along the Dead Sea–Aqaba Highway in Umm, Methla, Wadi Musa, Qa’ Saideen and Rahma, southern Jordan. Therefore, a comprehensive groundwater study was commenced by drilling eight new wells which can be used to supply irrigable areas with the existing groundwater that would be enriched by the yield of three proposed recharge dams on Wadi Musa, Wadi Abu-Burqa, and Wadi Rahma. The evaluation of the pumping test data of the drilled was carried out using the standard methods of pumping test interpretation. This was based on the available water table measurements at well locations and knowledge of water flow in the general. The sustainable yield of each well was calculated based on the pumping test parameters. The obtained results indicate that pumping out of Beer Mathkor wells should not exceed 1,100 m³/day in the case of continuous pumping and 8,700 m³/day in the case of intermittent pumping. Since the water table did not significantly change with small changes in pumping (it took eightfolds of magnitude increase in pumping from approximately 1,100 to 8,700 m³/day to show a significant drop in the water table equivalent to about 5.5 MCM per year from the aquifer.     

西南地区地质灾害调查工作的思考

本文根据近年来开展的1∶10万县(市)地质灾害调查与区划、1∶5万地质灾害详细调查等工作所取得的大量成果,对西南地质地质灾害调查工作进行总结,提出几大方面的建议。     

Developing an overall assessment map for flood hazard on large area watershed using multi-method approach: case study of Wadi Qena watershed,Egypt

Natural Hazards - Many parts of Upper Egypt as Sinai and Red Sea areas were hit by severe flash floods since 1976. Wadi Qena is considered one of the most watersheds that suffers from floods in Red...     

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。     

Geophysical characteristics of Wadi Hanifah water system, Riyadh, Saudi Arabia

Integrated geophysical techniques including resistivity image, vertical electrical sounding (VES), and seismic refraction have been conducted to investigate the Wadi Hanifah water system. The groundwater in Wadi Hanifah has problems caused by the high volumes of sewage water percolating into the ground. The combination of VES, resistivity image, and seismic refraction has made a valuable contribution to the identification of the interface between the contaminated and fresh water in Wadi Hanifah area. The contaminated groundwater has lower resistivity values than fresh groundwater due to the higher concentration of ions which reduces the resistivity. Resistivity image and sounding in this area clearly identified the nature of the lithological depth and proved useful at identifying water-bearing zones. Fresh groundwater was found in the study area at a depth of 100 m within the fractured limestone. Water-bearing zones occur in two aquifers, shallow contaminated water at 10 m depth in alluvial deposits and the deeper fresh water aquifer at a depth of about 100 m in fractured limestone. The interface between the contaminated water (sanitary water) and fresh water marked out horizontally at 100 m distance from the main channel and vertically at 20 m depth.     

Sinkhole hazards along the eastern Dead Sea shoreline area, Jordan: a geological and geotechnical consideration

For the last four decades, the level of the Dead Sea has been subjected to continual variation which, among other important factors, has led to the occurrence of much subsidence and many sinkholes in the southern Dead Sea area. Sinkhole activities occurred repetitively and were observed in open farms, across roads, near dwellings and near an existing factory, thus causing a serious threat to the locals and farmers of the area and their properties. This paper presents the main results from detailed geological and geotechnical studies of this area. Aerial photo interpretation and borehole drilling aided these studies. Parallel geophysical investigations (vertical electrical sounding and seismic refraction) and hydrological and hydrogeological studies were made by others in the same area to also investigate this phenomenon. It was found that sinkholes are aligned to and follow old water channels and are concentrated parallel to the recent shoreline of the Dead Sea. The development of subsurface cavities is associated mainly with the variation in the level of the Dead Sea over the four past decades, the presence of regional salt intrusion under the surface of salt beds, the fluctuation of the water table and continuous dissolution and the active tectonism of the area. Moreover, this work showed that the area is still under active sinkhole hazards and other parts of the area will be inevitably affected by sinkholes in the future.No practical engineering solution to this problem is feasible. Received: 1 July 1999 / Accepted: 11 October 1999     

Geochemical reconnaissance survey and environmental assessment for stream sediments of Wadi Um Gier,Southeastern Desert,Egypt

The purposes of this study were to assess the influence of old mining activities on the geochemistry and quality of sediments and to identify the sites of economic elements. Thirty sites of stream sediment were sampled in the study area covered by granitic, metarhyodacitic and meta-andesitic rocks and related tuffs-hosted abandoned Au mine. The suite of chemical elements, Ag, Bi, Cd, Cu, Fe, Ga, Hg, Mn, Nb, Pb, Rb, Sb, Se, Sn, Te, Th, U, Y, Zn and Zr, pH value and total organic carbon were determined, and univariate, bivariate and multivariate statistical methods were applied. The results show that the enrichment factor (EF) is very high in the case of Te and significant also with respect to Ag, Bi, Cu, Sb, Se, Sn and Zn. Likewise, geoaccumulation indices (Igeos) varied from very highly polluted with Sn and Te, strongly to very strongly polluted with Bi and Se, and moderately polluted with Sb. The polluted sites of Ag, Bi, Sb, Se, Sn and Te were outlined using Igeos maps, and economic sites of Ag and Sn were identified by geochemical maps leading to their sources, which are likely to be mining activities and lithogenic processes. The pollutant elements may cause toxicity in stream sediments, or surface or underground water, as well as plants and animals in the area. This investigation provides an environmental baseline for future monitoring of possible human/anthropogenic, industrial and agricultural impacts on the study area and considers an attempt at re-mining Ag and Sn.