Drought risk assessment using remote sensing and GIS techniques

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.     

A quantitative assessment of groundwater resources in the Middle East and North Africa region

The Middle East and North Africa (MENA) region is the world’s most water-stressed region, with its countries constituting 12 of the 15 most water-stressed countries globally. Because of data paucity, comprehensive regional-scale assessments of groundwater resources in the MENA region have been lacking. The presented study addresses this issue by using a distributed ArcGIS model, parametrized with gridded data sets, to estimate groundwater storage reserves in the region based on generated aquifer saturated thickness and effective porosity estimates. Furthermore, monthly gravimetric datasets (GRACE) and land surface parameters (GLDAS) were used to quantify changes in groundwater storage between 2003 and 2014. Total groundwater reserves in the region were estimated at 1.28 × 10⁶ cubic kilometers (km³) with an uncertainty range between 816,000 and 1.93 × 10⁶ km³. Most of the reserves are located within large sedimentary basins in North Africa and the Arabian Peninsula, with Algeria, Libya, Egypt, and Saudi Arabia accounting for approximately 75% of the region’s total freshwater reserves. Alternatively, small groundwater reserves were found in fractured Precambrian basement exposures. As for groundwater changes between 2003 and 2014, all MENA countries except for Morocco exhibited declines in groundwater storage. However, given the region’s large groundwater reserves, groundwater changes between 2003 and 2014 are minimal and represent no immediate short-term threat to the MENA region, with some exceptions. Notwithstanding this, the study recommends the development of sustainable and efficient groundwater management policies to optimally utilize the region’s groundwater resources, especially in the face of climate change, demographic expansion, and socio-economic development.     

Flood inundation mapping and hazard assessment of Baitarani River basin using hydrologic and hydraulic model

Frequent flood is a concern for most of the coastal regions of India. The importance of flood maps in governing strategies for flood risk management is of prime importance. Flood inundation maps are considered dependable output generated from simulation results from hydraulic models in evaluating flood risks. In the present work, a continuous hydrologic-hydraulic model has been implemented for mapping the flood, caused by the Baitarani River of Odisha, India. A rainfall time-series data were fed into the hydrologic model and the runoff generated from the model was given as an input into the hydraulic model. The study was performed using the HEC-HMS model and the FLO-2D model to map the extent of flooding in the area. Shuttle Radar Topographic Mission (SRTM) 90 m Digital Elevation Model (DEM) data, Land use/Land cover map (LULC), soil texture data of the basin area were used to compute the topographic and hydraulic parameters. Flood inundation was simulated using the FLO-2D model and based on the flow depth, hazard zones were specified using the MAPPER tool of the hydraulic model. Bhadrak District was found to be the most hazard-prone district affected by the flood of the Baitarani River. The result of the study exhibited the hydraulic model as a utile tool for generating inundation maps. An approach for assessing the risk of flooding and proper management could help in mitigating the flood. The automated procedure for mapping and the details of the study can be used for planning flood disaster preparedness in the worst affected area.

     

Integration of inland and coastal storms for flood hazard assessment using a distributed hydrologic model

Due to increasing flood severities and frequencies, studies on coastal vulnerability assessment are of increasing concern. Evaluation of flood inundation depth and extent is the first issue in flood vulnerability analysis. This study has proposed a practical framework for reliable coastal floodplain delineation considering both inland and coastal flooding. New York City (NYC) has been considered as the case study because of its vulnerability to storm surge-induced hazards. For floodplain delineation, a distributed hydrologic model is used. In the proposed method, the severities of combined inland and coastal floods for different recurrence intervals are determined. Through analyzing past storms in the study region, a referenced (base) configuration of rainfall and storm surge is selected to be used for defining flood scenarios with different return periods. The inundated areas are determined under different flooding scenarios. The inundation maps of 2012 superstorm Sandy in NYC is simulated and compared with the FEMA revised maps which shows a close agreement. This methodology could be of significant value to the planners and engineers working on the preparedness of coastal urban communities against storms by providing a platform for updating inundation maps as new events are observed and new information becomes available.     

Integrating hydrologic modeling and land use projections for evaluation of hydrologic response and regional water supply impacts in semi-arid environments

Semi-arid environments are generally more sensitive to urbanization than humid regions in terms of both hydrologic modifications and water resources sustainability. The current study integrates hydrologic modeling and land use projections to predict long-term impacts of urbanization on hydrologic behavior and water supply in semi-arid regions. The study focuses on the Upper Santa Clara River basin in northern Los Angeles County, CA, USA, which is undergoing rapid and extensive development. The semi-distributed Hydrologic Simulation Program Fortran (HSPF) model is parameterized with land use, soil, and channel characteristics of the study watershed. Model parameters related to hydrologic processes are calibrated at the daily time step using various spatial configurations of precipitation and parameters. Potential urbanization scenarios are generated on the basis of a regional development plan. The calibrated (and validated) model is run under the proposed development scenarios for a 10 year period. Results reveal that increasing development increases total annual runoff and wet season flows, while decreases are observed in existing baseflow and groundwater recharge during both dry and wet seasons. As development increases, medium-sized storms increase in both peak flow and overall volume, while low and high flow events (extremes) appear less affected. Urbanization is also shown to decrease natural recharge and, when considered at the regional scale, may result in a loss of critical water supply to Southern California. The current study provides a coupled framework for a decision support tool that can guide efforts involved in regional urban development planning and water supply management.     

Nomadism and desertification in Africa and the Middle East

Desertification in areas where traditional pastoral nomadism was common is a phenomenon of this century. Nomads possessed institutions and management practices that avoided excess concentrations of people and animals, rotated grazing pressure seasonally between major pasture zones, protected dry season resources that were critical to their survival, and limited access to pastoral resources. These systems of management and control have broken down and degradation of pastoral lands has been the result. The pressures promoting desertification include agricultural expansion into pastoral zones, the loss of critical dry season pasture, sedentarization of former nomads, the impacts of war and civil conflict, nationalization of pastoral resources, the collapse of traditional common property resource management systems, and social change and economic intensification. These processes have concentrated pastoral pressures into more limited spaces and increased the stress placed on natural resources to the point where land degradation takes place. These adverse changes can be avoided and desertification arrested if principles of proper management are applied. By planning holistically, using the ethnoscientific wisdom of nomadic pastoralists as a basis for development, protecting zones critical to the survival of pastoralists, retaining mobility and flexibility in contemporary pastoral systems, and strengthening common property systems developed by nomadic pastoralists, land degradation in dryland rangelands can be halted.     

东亚西太平洋巨型裂谷体系岩石圈与软流圈结构及动力学

笔者根据地震面波层析成像结果，对欧亚大陆及西太平洋岩石圈和软流圈速度结构进行了研究，发现东亚至西太平洋间存在一巨型低速异常带，结合构造地质学、地幔岩石学、地球化学及其他地球物理特性的研究，确认该区存在巨型裂谷体系。该巨型裂谷体系的岩石圈和软流圈三维Vs速度结构与太平洋洋中脊、大西洋洋中脊和印度洋洋中脊及其邻区的岩石圈和软流圈地震Vs速度结构十分相似，而与东太平洋边缘现代板块俯冲带的岩石圈与软流圈Vs速度结构有显著差异。在进一步论述该区动力学特征后认为，该巨型裂谷体系是中生代中晚期以来岩石圈整体主动伸展变形，大型裂陷盆地形成，岩石圈强烈拆沉减薄，以及软流圈物质上涌加热引起的。边缘海是在大陆裂谷系形成基础上发展起来的，主导扩张期为中渐新世至中中新世（32－13Ma），这些边缘海在17－15Ma后停止扩张，因而未能将所有边缘海和洋中脊联通。据此划分出4期构造变形动力学演化阶段，现今东亚至西太平洋间大陆裂谷、边缘海与沟弧体系是新生代中晚期以来，邻区各板块构造相互作用叠加的结果。     

Sodic amphiboles and pyroxenes from fenites in East Africa

During alkali metasomatism of the country-rock associated with ijolite-carbonatite complexes the development of sodic amphibole and/or pyroxene is characteristic. In this paper, some new chemical analyses of these minerals, together with published analyses from fenites of Kenya, Uganda and Tanzania, include those of co-existing pairs of amphibole and pyroxene. The common amphiboles of the fenites are magnesioarfvedsonites with 100 Mg: Mg+Fe+Mn ranging from 67 to 36. They co-exist with aegirines having 0.75 to 0.89 ions Fe⁺³. Most of these minerals are poor in Ca; co-existing pairs tend to show corresponding increases in Ca and in Fe⁺². In the syenitic fenites of Tororo and Budeda, considered to have formed at higher temperatures, the stable mineral is aegirine-augite. New analyses of richterite, magnesioarfvedsonite and aegirine from carbonate-rich rocks are also presented, and the relation between fenites and carbonatites is discussed.     

东非构造演化与油气成藏规律初探

随着非洲油气资源对外开放程度的加大,给我国海外石油战略提供了机遇。东非低勘探程度区油气地质资料匮乏,其油气勘探潜力综合评价和预测是目前的一个重点与难点,又是我国海外油气资源战略选区的需要。根据东非的区域构造演化和沉积充填特征,研究了东非地区的盐层序、水系分布、地热异常和保存条件等油气成藏主控因素及成藏规律。结果表明:被动大陆边缘盆地油气成藏主要受三角洲、海底扇、盐层序和泥岩盖层的发育程度和分布范围的控制,裂谷盆地主要受地堑地垒分布、裂谷作用形成的圈闭类型与规模、构造活动和岩浆作用的强度和范围的控制;被动大陆边缘盆地具有下伏Karoo群生气,盐层序分布区发育有利成藏组合,盆地的陆上部分油气成藏条件较差,大型三角洲与海底扇发育区勘探潜力好的成藏特征;裂谷盆地具有近距离成藏的特点,油气主要富集在构造活动、岩浆作用和地热异常相对较弱的紧临生烃坳陷的地垒周缘。总体上,东非地区具有远离Afar热柱勘探潜力变好的成藏规律。     

Drought disaster monitoring and land use dynamics: identification of drought drivers using regression-based algorithms

Natural Hazards - Droughts are particularly disastrous in South Africa and other arid regions that are water-scarce by nature due to low rainfall and water sources. According to some studies,...     

三维地质建模及可视化系统的设计与开发

三维地学模拟是三维地质信息GIS可视化的核心内容。基于基础GIS软件平台MAPGIS,利用功能强大的三维可视化开发平台MAPGIS-TDE,设计、开发具有自主版权的三维地质建模及可视化系统。MAPGIS-TDE包括MAPGIS内核模块、MAPGIS-TDE基础平台、MAPGIS-TDE构建平台和基于MAPGIS-TDE的应用系统等4个层次。基于MAPGIS-TDE的三维地质建模及可视化系统分为地质数据管理、二维地质分析、地质断面处理、地质结构建模和地质属性建模等5大功能模块。系统实现时,将空间数据库划分为基础地理图形库、区域地质数据库、工程地质数据库、水文地质数据库、地球物理数据库、地球化学数据库等6类。该系统不仅提供了强大的地质数据管理、三维地质建模以及模型的可视化功能,还为专业技术人员提供了一个可视化的分析、设计平台。     

Mineral resources and development in Africa

The Economy of African countries in colonial times was tied to those of Western developed countries largely through supply of their resources, as raw material, for industrialisation and markets for manufactured goods. Even today development is seen by many European countries only as an expansion of this role. But Africans themselves are beginning to regard process of industrialisation as the only way to increase their per capita income and reduce the present inequality in the world.The objective of most African countries to reach the level of prosperity of the Western Europe of today by the year 2000 can be achieved if a growth rate of 13% were possible. This rate, high and unattainable as it may look, will at that time produce hardly any appreciable closing of the gap in the per capita income of Western European and African nations. With the present rate of 6% growth for industrialised and developing countries the gap will widen unbridgeably by the year 2000.Africa depends largely on export of mineral resources for capital and will require even more mineral resources if it must industrialise. A survey of mineral resources of Africa shows that it has no mineral resources to give sustained impetus to industrialisation and is particularly lacking in energy. The desired rate of growth and industrialisation is heavily dependent on the political will of the Western developed countries, which to make this possible must allow massive transfer of capital and technology and a fairer world economic order. The alternative open to African countries is to go into economic and social isolation and attempt a revolutionary approach to development.Whichever approach is followed all African countries must develop new mineral policies which will lead to an accelerated and intensive exploration of the continent for greater variety and amount of metals and fuel minerals.

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Zusammenfassung Während der Kolonialzeit war die Wirtschaft Afrikas mit der westlicher entwickelter Länder im wesentlichen durch die Lieferung von Bodenschätzen als Rohstoff für die Industrialisierung und umgekehrt als Markt für Industriegüter verknüpft. Selbst heute noch wird Entwicklung von vielen europäischen Ländern als eine Ausweitung dieser Rolle gesehen. Doch die Afrikaner ihrerseits fangen an, den Prozeß der Industrialisierung als den einzigen Weg zu betrachten, ihr Pro-Kopf-Einkommen zu erhöhen und die gegenwärtige Ungleichheit in der Welt zu verringern.Das Ziel der meisten afrikanischen Länder, das Wohlstandsniveau des heutigen Westeuropas bis zum Jahre 2000 zu erreichen, würde voraussetzen, daß eine Wachstumsrate von 13% möglich wäre. Eine solche Rate, so hoch und unerreichbar sie aussehen mag, würde jedoch nicht die Lücke zwischen dem Pro-Kopf-Einkommen Westeuropas und dem afrikanischer Staaten zufriedenstellend verkleinern. Angesichts der gegenwärtigen Rate von 6% Wachstum für industrialisierte und Entwicklungsländer wird die Lücke sich bis zum Jahr 2000 unüberbrückbar weiter geöffnet haben.Afrika ist weitgehend abhängig vom Export von Bodenschätzen gegen Kapital, und es wird mehr Bodenschätze brauchen für eigene Industrialisierung. Eine Bestandsaufnahme der Bodenschätze Afrikas zeigt, daß keine ausreichenden Bodenschätze für eine andauernde Industrialisierung vorhanden sind, und es fehlt vor allem an Energierohstoffen. Die erstrebte Wachstumsrate und Industrialisierung hängt wesentlich von dem politischen Willen der westlichen entwickelten Länder ab, die, um die zu ermöglichen, für massiven Transfer von Kapital und Technologie und eine gerechtere Weltwirtschaftsordnung sorgen müßten. Die Alternative besteht in wirtschaftlicher und gesellschaftlicher Isolation und in revolutionären Entwicklungsversuchen.Welchen Weg die afrikanischen Länder auch wählen, sie müssen in bezug auf ihre Bodenschätze eine neue Politik entwickeln, die zu einer schnelleren und gründlicheren Erschließung des Kontinentes hinsichtlich einer größeren Menge und Vielfalt an Metallen und Energierohstoffen führt.

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Résumé Au temps du colonialisme, l'économie africaine était essentiellement liée aux pays développés de l'ouest par la livraison de richesses naturelles en tant que matières premières pour l'industrialisation dans un sens, et en tant que marché pour les marchandises industrielles dans l'autre. Aujourd'hui encore, beaucoup de pays européens voient dans l'aide aux pays en voie développement, un élargissement de ce rôle. Pourtant, les africains de leur côté, commencent à considérer le procès de l'industrialisation comme la seule voie pour élever leur revenu moyen et pour réduire l'inégalité dans le monde à l'époque actuelle.Pour que la plupart des pays africains puissent atteindre le niveau de prospérité de l'actuelle Europe de l'ouest, avant l'an 2000, il faudrait à priori, un taux de croissance de 13%. Cependant, un tel taux, aussi haut et inaccessible qu'il puisse paraître, ne pourrait pas diminuer de façon satisfaisante l'espace entre le revenu moyen en Europe de l'ouest et celui des pays africains. Vu le taux de développement actuel de 6% aussi bien en pays industriels qu'en pays en voie de développement, cet espace ne fera que de s'agrandir jusqu'à l'an 2000 et ceci de façon insurmontable.L'Afrique dépend, en majeur partie, de l'exportation de richesses naturelles contre des capitaux et il lui faudra encore plus de richesses naturelles pour réaliser sa propre industrialisation. Un inventaire de richesses naturelles de l'Afrique montre qu'il n'y a pas de richesses naturelles suffisantes pour une industrialisation de longue durée et qu'il y manque, avant tout, de matières premières énergétiques. Le future taux de développement et d'industrialisation dépend essentiellement du consentement politique des pays de l'ouest, qui dans ce but devraient pourvoir à d'importants transferts de capitaux et de technologie et à un ordre équitable de l'économie mondiale. La seule alternative consiste dans l'isolation économique et sociale et dans des essais de développement révolutionnaires.Quelque soit la voie prise par les pays africains, il leur faudra développer une politique nouvelle en ce qui concerne leurs richesses naturelles. Cette politique les conduira vers une mise en exploitation plus profonde du continent, en vue de produire une plus grande quantité et multiplicité de métaux et de matières premières énergétiques.

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Hard-rock aquifers in tropical regions: using science to inform development and management policy

An overview of progress during the past 30 years in the hydrogeologic understanding of groundwater in hard-rock aquifers of tropical regions is presented. Geographically, the paper concentrates upon and contrasts Tropical Africa and Peninsular India, where very extensive areas of weathered hard-rock aquifers occur, but its conclusions are more widely applicable. This scientific understanding forms the basis for a critical discussion of key policy issues for the development and management of the water resources of these aquifers, given their major importance for economical and sustainable water-supply provision, in the context of efforts to achieve the UN Millennium Development Goals for rural drinking water and improved livelihoods.     

矿床模型综合地质信息预测技术研究

随着中国国民经济持续快速发展,中国对矿产资源的需求呈现了快速增长的趋势,资源短缺已经成为制约中国经济又好又快发展的主要瓶颈之一。为了解决矿产资源短缺问题,对陆地近地表未查明矿产资源潜力的区位、数量和质量的评价工作已经成为当前十分迫切的任务。文章对矿床模型综合地质信息预测技术体系进行了详细、系统的介绍。该体系以地球动力学、成矿动力学和成矿系列理论为指导,深入开展区域地质构造研究,最大限度地分析地质构造的成矿信息,以各级成矿区带为单元,划分主要矿产的矿床预测类型,建立矿床模型,总结区域成矿系列。全面利用物探、化探、遥感等资料所显示的地质找矿信息,运用体现地质成矿规律内涵的预测技术,全面、全过程应用空间数据库及GIS技术,在圈定成矿预测区的基础上估计潜在资源量。     

植物叶蜡单体氢同位素重建非洲和东亚大陆古降水:亮点与难点

植物利用周围环境中的水分进行光合作用合成有机质, 其叶蜡氢同位素记录了源水中的氢同位素组成, 被认为是重建古水循环的替代性指标。然而从源水(降水)到合成叶蜡脂类化合物, 降水中的氢同位素会发生多步分馏作用。本文综述了对氢同位素分馏造成影响的因素及其校正方法, 通过有效的数据处理, 叶蜡氢同位素可以比较直接地反映降水的氢同位素组成。由于在热带地区降水氢同位素受"雨量效应"影响较大, 所以可以较好地反映降水量变化, 在非洲大陆常被用于重建水循环和气候变化; 在东亚大陆,"雨量效应"不再那么显著, 水汽的来源可能在影响降水氢同位素组成的过程中也起到了重要作用。     

Inequality and development in rural West Africa

Inequality seems to be a feature of all societies, but some are probably more equal than others. It is in Third World countries however where inequalities between particular areas, groups and individuals are most marked. The paper first traces the growing interest in both the study of inequality and the rural household as a focus of analysis. Some of the problems of measuring inequality are then considered and various indicators of inequality are examined with reference to empirical evidence from rural W Africa. The paper concludes that recent development strategies have often directly or indirectly led to greater rural inequality and makes suggestions as to how future projects might achieve greater impact in reducing the gap between rich and poor. Paper presented at Commonwealth Geographical Bureau, Workshop on Spatial Inequalities in the Developing World, Kano, Nigeria 16–20 September 1985