Historical development and future outlook of the flood damage potential of residential areas in the Alpine Lech Valley (Austria) between 1971 and 2030

In the recent past, the Alpine Lech valley (Austria) experienced three damaging flood events within 6 years despite the various structural flood protection measures in place. For an improved flood risk management, the analysis of flood damage potentials is a crucial component. Since the expansion of built-up areas and their associated values is seen as one of the main drivers of rising flood losses, the goal of this study is to analyze the spatial development of the assets at risk, particularly of residential areas, due to land use changes over a historic period (since 1971) and up to possible shifts in future (until 2030). The analysis revealed that the alpine study area was faced to remarkable land use changes like urbanization and the decline of agriculturally used grassland areas. Although the major agglomeration of residential areas inside the flood plains took place before 1971, a steady growth of values at risk can still be observed until now. Even for the future, the trend is ongoing, but depends very much on the assumed land use scenario and the underlying land use policy. Between 1971 and 2006, the annual growth rate of the damage potential of residential areas amounted to 1.1 % (‘constant values,’ i.e., asset values at constant prices of reference year 2006) or 3.0 % (‘adjusted values,’ i.e., asset values adjusted by GDP increase at constant prices of reference year 2006) for three flood scenarios. For the projected time span between 2006 and 2030, a further annual increase by 1.0 % (‘constant values’) or even 4.2 % (‘adjusted values’) may be possible when the most extreme urbanization scenario ‘Overall Growth’ is considered. Although socio-economic development is regarded as the main driver for increasing flood losses, our analysis shows that settlement development does not preferably take place within flood prone areas.     

长江上游洪涝灾害分析及防灾减灾措施

分析了长江上游洪水和渍涝灾害的发生频率、危害程度和演变趋势。在季风环流和山区地形抬升作用下，形成长江上游４个年雨量大于２０００ｍｍ的暴雨中心，使盆周和乌江上游成为雨洪多发区，各大江河汇合口普遍存在洪泛之害。夏季山洪、秋季雨涝、沿江洪水淹没和山区泥石流等水害频繁，且灾害的发生频率和造成的损失有继续增大的趋势，通过对历史灾情的分析，提出了洪涝频率和面积分布。洪涝灾害的危害程度既受天气异常的影响，又与人类活动密切相关。长江上游的防洪抗灾应采取因地制宜、综合治理的方针，即结合大型水库控制、水土保持、农田水利、灾害预警和社会保险等措施消减灾害，其中尤以长江上游防护林和大江河干流水库枢纽作用巨大，可起到削蓄洪水、涵养水源、减少侵蚀和改善生态环境条件的综合功效，是带根本性的流域治理措施。     

Flood risk,climate change and settlement development: a micro-scale assessment of Austrian municipalities

This paper analyses the influence of climate change and land development on future flood risk for selected Austrian flood-prone municipalities. As part of an anticipatory micro-scale risk assessment we simulated four different inundation scenarios for current and future 100- and 300-year floods (which included a climate change allowance), developed scenarios of future settlement growth in floodplains and evaluated changes in flood damage potentials and flood risk until the year 2030. Findings show that both climate change and settlement development significantly increase future levels of flood risk. However, the respective impacts vary strongly across the different cases. The analysis indicates that local conditions, such as the topography of the floodplain, the spatial allocation of vulnerable land uses or the type of land development (e.g. residential, commercial or industrial) in the floodplain are the key determinants of the respective effects of climate change and land development on future levels of flood risk. The case study analysis highlights the general need for a more comprehensive consideration of the local determinants of flood risk in order to increase the effectiveness of an adaptive management of flood risk dynamics.     

Evaluating the effect of flood damage-reducing measures: a case study of the unembanked area of Rotterdam,the Netherlands

Empirical evidence of increasing flood damages and the prospect of climatic change has initiated discussions in the flood management community on how to effectively manage flood risks. In the Netherlands, the framework of multi-layer safety (MLS) has been introduced to support this risk-based approach. The MLS framework consists of three layers: (i) prevention, (ii) spatial planning and (iii) evacuation. This paper presents a methodology to evaluate measures in the second layer, such as wet proofing, dry proofing or elevating buildings. The methodology uses detailed land-use data for the area around the city of Rotterdam (up to building level) that has recently become available. The vulnerability of these detailed land-use classes to flooding is assessed using the stage–damage curves from different international models. The methodology is demonstrated using a case study in the unembanked area of Rotterdam in the Netherlands, as measures from the second layer may be particularly effective there. The results show that the flood risk in the region is considerable: EUR 36 million p.a. A large part (almost 60 %) of this risk results from industrial land use, emphasising the need to give this category more attention in flood risk assessments. It was found that building level measures could substantially reduce flood risks in the region because of the relatively low inundation levels of buildings. Risk to residential buildings would be reduced by 40 % if all buildings would be wet-proofed, by 89 % if all buildings would be dry-proofed and elevating buildings over 100 cm would render the risk almost zero. While climate change could double the risk in 2100, such building level measures could easily nullify this effect. Despite the high potential of such measures, actual implementation is still limited. This is partly caused by the lack of knowledge regarding these measures by most Dutch companies and the legal impossibility for municipalities to enforce most of these measures as they would go beyond the building codes established at the national level.     

Groundwater market and its implications on water resources and agriculture in the southern peri-urban interface,Chennai, India

This paper describes the informal groundwater market existing in the urban–peri-urban interface of Chennai. The private water tanker suppliers and packaged water industries utilize the land and water resources of the peri-urban villages. Thus, the groundwater sources in peri-urban areas play a significant role in meeting the growing urban demand. The villages that are experiencing the groundwater market are highly influenced by the urbanization and its related activities, due to their proximity to the city. The transfer of groundwater from the peri-urban villages not only deprives the peri-urban areas of their water rights but also leads to environmental damage. Agriculture declined in the water marketed villages in the range of 20–95 per cent during 1990–2007. The pre-monsoon and post-monsoon groundwater level fluctuation varied from 2–6 m to 0–5 m, respectively, during 1971–2007. The declining trend of the groundwater table and agriculture is highly significant in the water marketing villages. Moreover, the present groundwater quality is also in a susceptible state due to over extraction. Hence, strengthening the legal and institutional framework to ensure an equitable access to water for both urban and peri-urban areas is urgently required. This paper also describes the characteristics of the groundwater transfer, quantification of the marketed water, the role of the existing regulatory framework, and the institutional mechanisms. Many stakeholder’s meeting and focus group discussions have been conducted in the villages under study for understanding the socio-economic implications of the water market. The study ultimately emphasized a sustainable groundwater extraction/market which will safeguard the interests of the peri-urban and urban communities.     

基于洪水过程的农业洪灾变化遥感快速评估模型及其应用

洪涝灾情的准确测度需要同时兼顾淹没区的面积大小和淹水时长信息。利用淹没区内由水和作物等多种地物所组成的"复合水体"不同于水体的波谱时间变化特性,将不同洪灾时期的水体指数和植被指数进行信息复合,以有效凸显水体和洪涝淹没区之间的影像差异,据此进行了灾初期、峰期和中后期等3个时次受淹范围的有效识别。在此基础上,根据洪涝灾情随着淹没时长而加重以及灾区内淹水时长非均匀分布的特性,建立基于淹没时长的受淹面积不等权参与的洪灾扩展动态度指数(Variation Index of Flood,VIF)和区域灾情比较指数(Comparison Index of Flood Disaster,CIFD)两种模型,并将模型应用于鄱阳湖区2016年夏季农业洪涝灾害的时空变化遥感监测。结果显示,应用上述两种模型不仅可以准确获取鄱阳湖区本次农业洪涝灾情的演变趋势,而且能够方便地对比分析区域内不同地方的受灾程度。鄱阳湖区在2016年6月23日~7月25日期间的洪涝灾情具有由弱增强再趋弱的特征,其VIF指数由初始阶段(6月23日~7月9日)的3.75降至后续阶段(7月9日~7月23日)的1.29;鄱阳县是研究区内受灾最严重的区域,其CIFD指数值居于研究区内各受灾县市之首,该县受灾总面积以及多次被淹的灾区面积均高于其他县市。     

Vulnerability assessment of sea-level rise in Viti Levu, Fiji Islands

Fiji is expected to come under increasing pressure and risk from various threats resulting from climate change and sea-level rise (SLR). Fiji consists of 332 islands and thus has a predominant and large coastline. Viti Levu is the largest and most important of the islands, harboring Fiji’s capital city and most of the major towns concentrated around its coast. The objectives of this study were to evaluate the extent of possible sea-level rise using GIS, and to identify high-risk locations. Potential sea level rise was shown graphically as an output to determine where inundation or flooding would take place. This analysis allowed important areas facing risk to be highlighted for future action. Flooding/inundation can be classified into two kinds: ‘permanent inundation’, which is the result of sea-level rise with tide; and ‘temporary flooding’, also including occasional storm surge events. The inundated area was displayed under different projections and quantified. The results produced output maps showing the distribution of inundation/flooding around the island of Viti Levu as well as the extent of flooding. Six scenarios for sea-level rise were used (0.09, 0.18, 0.48, 0.50, 0.59, 0.88 m). Six scenarios for storm surge were used with return intervals of 1, 2, 5, 10, 25, 50 years. High risk and priority locations are identified as Fiji’s capital Suva, the major tourist center and arrival port of Nadi, and Fiji’s second city Lautoka. Future action, adaptation and response strategies in these identified locations must occur to reduce risk from climate change.     

基于AFI指数的汉江上游流域洪涝突变辨识

洪涝灾害往往容易在短期内突然发生，从而造成巨大的人员伤亡和财产损失，但目前有关突发性洪涝现象的甄别与分析并没有达成共识。在利用标准化前期降水指数SAPI(Standardized Antecedent Precipitation Index)评估出逐日洪涝状态的基础上，提出突变性洪涝指数AFI(Abrupt Flood Index)以综合反映水量由前期（当天）到后期（后10天）突变及后期洪涝程度，同时定义并计算AFI阈值AFI_t，认为AFI超过AFI_t的日期为临界状态，后期将发生突变性洪涝事件。以汉江上游流域为例计算出该流域1972~2017年逐日AFI指数，并利用AFI_t判别出了处于临界状态的日期。进一步分析表明，AFI指数能够较好地反映突变性洪涝现象，利用AFI指数甄别出的洪涝临界状态有利于识别流域突变性洪涝事件并有助于流域水资源系统应急管理。     

Contamination of drinking water resources in the Mekong delta floodplains: arsenic and other trace metals pose serious health risks to population

This study presents a transnational groundwater survey of the 62,000 km(2) Mekong delta floodplain (Southern Vietnam and bordering Cambodia) and assesses human health risks associated with elevated concentrations of dissolved toxic elements. The lower Mekong delta generally features saline groundwater. However, where groundwater salinity is <1 g L(-)(1) Total Dissolved Solids (TDS), the rural population started exploiting shallow groundwater as drinking water in replacement of microbially contaminated surface water. In groundwater used as drinking water, arsenic concentrations ranged from 0.1-1340 microg L(-)(1), with 37% of the studied wells exceeding the WHO guidelines of 10 microg L(-)(1) arsenic. In addition, 50% exceeded the manganese WHO guideline of 0.4 mg L(-)(1), with concentrations being particularly high in Vietnam (range 1.0-34 mg L(-)(1)). Other elements of (minor) concern are Ba, Cd, Ni, Se, Pb and U. Our measurements imply that groundwater contamination is of geogenic origin and caused by natural anoxic conditions in the aquifers. Chronic arsenic poisoning is the most serious health risk for the ~2 million people drinking this groundwater without treatment, followed by malfunction in children's development through excessive manganese uptake. Government agencies, water specialists and scientists must get aware of the serious situation. Mitigation measures are urgently needed to protect the unaware people from such health problems.     

Migration and reclamation in Northeast China in response to climatic disasters in North China over the past 300?years

Climatic disaster-induced migration and its effects on land exploitation of new settlements is a crucial topic that needs to be researched to better understand the impact of climate change and human adaptation. This paper focuses on the process and mechanism of migrant–reclamation in Northeast China in response to climatic disasters over the past 300 years. The research used comparative analysis of key interlinked factors in this response involving drought/flood events, population, cropland area, farmer revolts, administrations establishment, and land reclamation policies. It draws the following conclusions: (1) seven peaks of migrants–reclamation in Northeast China were evident, most likely when frequent climatic disasters happened in North China, such as the drought–flood in 1851–1859, drought in 1875–1877, and drought 1927–1929; (2) six instances of policy transformation adopted to cope with extreme climatic events, including distinctive examples like changing to a firm policy prohibiting migration in 1740 and a subsequent lifting of that prohibition in 1860; and (3) the fast expansion of the northern agricultural boundary since the middle of the nineteenth century in this area benefited from a climate change trend from a cold period into a warm period. Altogether, over the past 300 years, extreme climatic disasters in North China have deepened the contradiction between the limited land resources and the rapidly increasing population and have resulted in migration and reclamation in Northeast China. Climate, policy, and reclamation constructed an organic chain of response that dominated the land use/cover change process of Northeast China.     

鄱阳湖流域城市洪涝灾害风险及土地类型调整策略研究 ——以景德镇市为例

在全球气候变化和人类活动影响下，流域内城市洪涝灾害发生的频率、强度及其造成的损失日益加剧，更好的揭示洪涝灾害风险的时空演变规律对不同流域下城市防灾减灾具有重要意义。基于流域城市洪涝灾害风险的形成过程，从致灾因子、孕灾环境、承灾体、防灾减灾能力4个方面选取指标，构建了基于格网的流域城市小尺度洪涝灾害风险评价模型，并以景德镇市城区为例，将空间风险定量计算，分析了城市洪涝风险的时空分异特征，最后提出土地利用类型的调整策略。结果表明:从空间上，城区洪涝灾害风险极大值与极小值差值存在较大的差异，呈现由昌江、南河、西河等河流为中心向四周逐渐减小的方向性变化，不同区域的风险波动性幅度不同，社会经济发展水平较高的珠山区昌江沿岸区域为景德镇城区的洪涝灾害高风险区，西部、西南部山区以及东部乡镇由于地势较高，风险水平较低。从时间上，景德镇市城区的洪涝灾害风险最大值呈下降趋势，南部洪涝灾害风险整体变小，但风险集中程度不断加剧，城区西部风险值有小幅度的上升；针对不同的区域特征，通过两种方案对城区内洪涝灾害易涝典型地区进行土地利用类型调整，两个区域风险分别从0.606与0.610降低到0.561与0.571。     

2005年中国气态α HCH的人体暴露和健康风险分析

为评估由我国大气中α HCH所导致的人体健康风险,利用CanMETOP 模拟的2005年日均α HCH大气浓度,基于吸入因子和致癌风险进行研究。结果表明年吸入因子呈东部>西部,北部>南部的特征，东中和东北部地区的吸入因子分别主要由人口密度和α HCH大气浓度贡献，东中和东南部地区的个体健康损失小于东北地区，东中和东南部地区年内逐月吸入因子分配较为均匀,而东北地区主要集中的夏季，东北地区个体致癌风险系数明显高于中部和南部。推测由其它污染物所形成的暴露风险具有类似的时空分布。加之夏季东北地区集中降水所形成的湿沉降以及气温升高等因素,使摄食暴露和皮肤接触暴露增大,东北地区人群的复合暴露风险将显著大于其它地区     

Evaluating the cost of flood damage based on changes in extreme rainfall in Japan

We estimated the cost of flood damage using numerical simulations based on digital map data and the flood control economy investigation manual submitted by the Ministry of Land, Infrastructure, Transportation, and Tourism in Japan. The simulation was carried out using a flood model incorporating representative precipitation data for all of Japan. The economic predictions, which estimate flood damage caused by extreme rainfall for the return periods of 5, 10, 30 50, and 100 years, are as follows: (1) the cost of flood damage increases nearly linearly with increases in extreme precipitation; (2) assuming that flood protection is completed for a 50-year return period of extreme rainfall, the benefit of flood protection for a 100-year return period of rainfall is estimated to be 210 billion USD; (3) the average annual expected damage cost for flooding is predicted to be approximately 10 billion USD per year, based on the probability of precipitation for a return period of 100 years and assuming that flood control infrastructures will be completed within the 50-year return period and will be able to protect from flooding with a 50-year return period; (4) urban and rural areas are predicted to suffer high and low costs of damage, respectively. These findings will help to derive measures to enhance flood protection resulting from climate change.     

鄱阳湖水位-淹水面积关系不确定性的分析

湖泊淹水范围的时空变化特征往往决定了湖泊湿地的景观结构和功能。鄱阳湖是我国最大淡水湖,水位和淹水范围的季节变化悬殊,鄱阳湖淹水特征对研究鄱阳湖湿地生态系统的结构与功能都具有显著意义,过去很多研究关注鄱阳湖水位-淹水面积关系,不同的研究者得到的水位-淹水面积关系各有差异,表现出一定的不确定性。利用多时相的卫星遥感影像提取的鄱阳湖水面面积的基础上,结合鄱阳湖长时间序列的水位观测资料,探讨鄱阳湖水位-淹水面积关系不确定的原因。研究结果表明:(1)尽管鄱阳湖水面面积与水位表现分段线性关系,但在相同水位条件下,鄱阳湖水面面积表现出较大的不确定性;(2)鄱阳湖水位表现南高北低的空间异质性格局,随着水位增加,鄱阳湖水位的空间异质性降低,并且水面坡降具有季相性,相同水位下退水期的水面坡降大于涨水期的水面坡降;(3)受洲滩地形和"堑秋湖"渔业方式的影响,相同水位下退水期出露洲滩中子湖泊的水面范围大于涨水期中子湖泊水面范围;(4)此外,鄱阳湖采砂显著改变采沙场的湖盆地形,从而改变低水位下的主要采沙场的淹水范围。综上所述,鄱阳湖水位-淹水面积关系的不确定性除了受湖盆地形、"五河"来水、长江顶托等自然原因,还有采砂和堑秋湖渔业方式等人类活动的原因。     

流域地理景观生成中纹理映射技术

洪水演进仿真系统的研制是进行“数字流域”工程建设的重要研究内容,系统的研制必须利用先进的模拟仿真与可视化方法等现代计算机技术,在计算机生成的虚拟环境中,对洪水在现实河道里的推进情况以及洪水对流域内区域的淹没情况进行仿真模拟。系统的可视化以流域地形的仿真为基础,流域三维景观的生成则是洪水演进仿真系统的主要可视化需求,纹理映射技术是实现流域三维景观的重要技术手段。在分析比较计算机图形学中的几种典型纹理映射方法基础上,针对复杂流域地形貌和卫星遥感流域数据源特点,研究了相应的纹理映射算法模型。使用Visual C 系统开发语言,依据清江流域的真实数据源生成清江流域三维网格地形,并基于OpenGl技术,运用逆透视过程和非参数映射方法,实现了清江流域三维景观的真实纹理粘贴,使生成的流域景观具有真实自然的三维可视化效果。     

Arsenic and other trace elements contamination in groundwater and a risk assessment study for the residents in the Kandal Province of Cambodia

Concentrations of arsenic and other trace elements in groundwater were examined at three villages (PT, POT and CHL) in the Kandal Province of Cambodia. Concentrations of arsenic in the groundwater ranged from 6.64 (in POT village) to 1543 microg/L (in PT village), with average and median concentrations of 552 and 353 microg/L, respectively. About 86% out of fifteen samples contained arsenic concentrations exceeding the WHO drinking water guidelines of 10 microg/L. Concentrations of arsenic (III) varied from 4 (in POT village) to 1334 microg/L (in PT village), with an average concentration of 470 microg/L. In addition, about 67%, 80% and 86% of the groundwater samples had higher concentrations for, respectively, barium, manganese and lead than the WHO drinking water guidelines. These results reveal that groundwater in Kandal Province is not only considerably contaminated with arsenic but also with barium, manganese and lead. A risk assessment study found that one sample (PT25) had a cumulative arsenic concentration (6758 mg) slightly higher than the threshold level (6750 mg) that could cause internal cancer in smelter workers with chronic exposure to arsenic from groundwater. High cumulative arsenic ingestion poses a health threat to the residents of Kandal Province.     

基于情景分析的区域洪涝灾害风险评价——以巢湖流域为例

洪涝灾害是制约区域粮食安全和社会可持续发展的主要因子之一。在风险识别的基础上,从致灾因子、孕灾环境、承灾体等方面选取评价指标,建立评价指标体系。运用层次分析法确定指标权重,通过情景分析技术从降水、土地利用、人口、GDP等方面构建复合情景;应用GIS空间分析技术构建洪涝灾害风险评价模型,对巢湖流域洪涝灾害风险进行评价。研究结果表明:2020年巢湖流域洪涝灾害危险性由东南部向西北部减小;合肥市区的洪涝灾害易损性最大,和县的易损性最小。巢湖流域东南部洪涝灾害风险最大,西南部的大别山区风险较小,随着重现期的增大,流域的洪涝灾害风险也逐渐增大。模拟灾害发生的情景,并分析不同情景下的洪涝灾害风险,更能体现洪涝灾害的不确定性和变化性,为流域防洪战略决策研究提供科学依据。     

Assessing relative vulnerability to sea-level rise in the western part of the Mekong River Delta in Vietnam

The Mekong River Delta in Vietnam plays a crucial role for the region in terms of food security and socioeconomic development; however, it is one of the most low-lying and densely populated areas in the world. It is vulnerable to seawater incursion, flood risk, and shoreline change, exacerbated as a consequence of sea-level rise (SLR) related to climate change. This study examined the Kien Giang coast in the western part of the delta, comprising seven coastal districts (namely Ha Tien, Kien Luong, Hon Dat, Rach Gia, Chau Thanh, An Bien, and An Minh), the economy of which is important in terms of agriculture and aquaculture. The analytical hierarchical process (AHP) method of multi-criteria decision making was integrated directly into geographic information systems (GIS) to derive a composite vulnerability index that indicated areas most likely to be vulnerable to SLR. The hierarchical structure comprised three key components: exposure (E), sensitivity (S), and adaptive capacity (A), at level 1. At the next level, 8 sub-components were mapped: seawater incursion, flood risk, shoreline change, population characteristics, land use/land cover, and socioeconomic, infrastructure, and technological capability, beyond which a further 22 variables (level 3) and 24 sub-variables (level 4) related to vulnerability were also mapped. Variables were assigned weights for incorporation into AHP pairwise comparisons after discussion with stakeholders. Maps were generated to visualise areas where the relative vulnerability was very low, low, moderate, high, and very high. Societal data were generally only available at district level; however, several regional patterns emerged. Relatively high exposure to flooding and inundation, salinity, and moderate loss of mangroves occurred along the coastal fringe of each district. This western section of the delta, which is low-lying and remote from the distributaries that carry sediment to the coast, appears to be particularly vulnerable. The most sensitive areas tended to be ethnic households engaged in rice cultivation and with moderate population density. The least adaptable areas consisted of high numbers of poor households, with low income, and moderate densities of transport, irrigation and drainage systems. Most coastal districts were determined to be moderately to relatively highly vulnerable, with scattered hotspots along the coast.     

Anthropogenic influence on the water quality in Guanabara Bay, Rio de Janeiro, Brazil

Guanabara Bay is a 384-km² coastal bay with 70% of the population of the metropolitan area of Rio de Janeiro located within its drainage basin. The water quality of the Bay is impacted by domestic and industrial runoff, of which only 15% has been adequately treated. However, based on a 14-year monitoring program, the water quality for most of Guanabara Bay remains acceptable because of intense tidal flushing, and we failed to find a worsening of conditions during the 14-year study. The inner shallow regions of the Bay, the western and northwestern parts, receive most of the drainage from metropolitan Rio de Janeiro. It is here that the water quality is alarmingly poor, characterized by hypertrophic conditions and occasional hypoxic events. Fecal coliform counts in these inner reaches of the Bay are 4–100 times higher than the maximum acceptable count for recreational waters. Hypertrophic conditions prevail in Guanabara Bay, which is characterized by low dissolved oxygen, high biochemical oxygen demand, peaks in fecal coliform, and extremely high chlorophyll-a concentrations, which reflect high quantities of nutrients entering the system. These anthropogenic pressures are a threat to planktonic and benthic communities and are reminiscent of San Francisco Bay 30 years ago. The Guanabara Bay water quality could be returned to pre-1950 conditions, but it would require sufficient political will and economic investment to ensure that at least 80–90% of the domestic and industrial sewage were treated adequately. Electronic Publication     

Health risk assessment for uranium in Korean groundwater

We analyzed the radiological and chemical risks of uranium in groundwater. The total sample number over 4 years was 498. There were several use patterns of groundwater in Korea, but we considered the risk only for drinking water. The geometric mean of uranium concentration in 10 areas in Korea was 0.17 microg x l(-1). The excess cancer risks were in the 10(-7) level in the radiological risk aspect and the hazard quotient was 0.005 in the chemical risk aspect. Therefore, we could conclude that an adverse health risk is unlikely to be posed due to exposure to uranium. However, the concentration of uranium must be monitored periodically and adequate action taken in the few and small areas that contain high uranium levels in groundwater.