A Hydraulic MultiModel Ensemble Framework for Visualizing Flood Inundation Uncertainty

While deterministic forecasts provide a single realization of potential inundation, the inherent uncertainty associated with forecasts also needs to be conveyed for improved decision support. The objective of this study was to develop an ensemble framework for the quantification and visualization of uncertainty associated with flood inundation forecast maps. An 11‐member ensemble streamflow forecast at lead times from 0 to 48 hr was used to force two hydraulic models to produce a multimodel ensemble. The hydraulic models used are (1) the International River Interface Cooperative along with Flow and Sediment Transport with Morphological Evolution of Channels solver and (2) the two‐dimensional Hydrologic Engineering Center‐River Analysis System. Uncertainty was quantified and augmented onto flood inundation maps by calculating statistical spread among the ensemble members. For visualization, a series of probability flood maps conveying the uncertainty in forecasted water extent, water depth, and flow velocity was disseminated through a web‐based decision support tool. The results from this study offer a framework for quantifying and visualizing model uncertainty in forecasted flood inundation maps.     

Measurements of indoor radon concentrations in the Santiago de Compostela area

Galician soils are among those with the highest (222)Rn exhalation rates in Spain. A year-round study of the indoor (222)Rn concentration in buildings in the Santiago de Compostela area (Galicia, Northwest of Spain) was performed. The study is based on systematic samplings with active charcoal canisters, following a modified EPA 520/5-87-005 protocol. These measurements were complemented by others obtained using etched track dosimeters. Each data set follows a log-normal distribution, with a geometric mean of (253+/-3)Bqm(-3) for charcoal canisters and (285+/-2.5)Bqm(-3) for etched track detectors. After correcting for the different measuring conditions, the mean value of both methods differed by only 2%. A careful analysis of the seasonal dependence of our measurements did not reveal any significant seasonal variations in the (222)Rn concentration. Parallel to these measurements, different meteorological parameters were recorded, which revealed a direct correlation between the indoor radon concentration and the outdoor temperature derivative with respect to time.     

Radon remediation of a two-storey UK dwelling by active sub-slab depressurisation: effects and health implications of radon concentration distributions

Radon concentration levels in a two-storey detached single-family dwelling in Northamptonshire, UK, were monitored continuously throughout a 5-week period during which active sub-slab depressurisation remediation measures were installed. Remediation of the property was accomplished successfully, with both the mean radon levels and the diurnal variability greatly reduced both upstairs and downstairs. Following remediation, upstairs and downstairs radon concentrations were 33% and 18% of their pre-remediation values respectively: the mean downstairs radon concentration was lower than that upstairs, with pre- and post-remediation values of the upstairs/downstairs concentration ratio, R(U/D), of 0.81 and 1.51 respectively. Cross-correlation between upstairs and downstairs radon concentration time-series indicates a time-lag of the order of 1 h or less, suggesting that diffusion of soil-derived radon from downstairs to upstairs either occurs within that time frame or forms a relatively insignificant contribution to the upstairs radon level. Cross-correlation between radon concentration time-series and the corresponding time-series for local atmospheric parameters demonstrated correlation between radon concentrations and internal/external pressure difference prior to remediation; this correlation disappears following remediation. Overall, these observations provide further evidence that radon concentration levels within a dwelling are not necessarily wholly determined by the effects of soil-gas advection, and further support the suggestion that, depending on the precise content of the building materials, upstairs radon levels, in particular, may be dominated by radon exhalation from the walls of the dwelling, especially in areas of low soil-gas radon.     

Radon mapping by retrospective measurements - an approach based on CDs/DVDs

This article points out the ability to map retrospective ²²²Rn concentrations by home stored CDs/DVDs. The method employs the high radon absorption ability of the polycarbonate material of CDs and DVDs and their track-etch properties. The principle steps for the application of the method are addressed. The possibility for individual a posteriori calibration is studied, demonstrating that better than 10% accuracy in retrospective measurements is potentially achievable. Results from retrospective measurements in three different regions are shown, demonstrating the potential of the method for large-scale radon mapping. Comparison with independently evaluated retrospective ²²²Rn concentrations in places with known radon history was made and very good correspondence was observed. The experience indicates that the method can be used for large scale retrospective radon mapping and its applications can be expanded towards mapping of radon concentrations in water and soil gas.     

Modeling the Pb activity concentration in the lower atmosphere

A worldwide radionuclide network of 80 stations, part of the International Monitoring System, is being setup to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The radioactivity sampled at these stations is primarily ²²⁰Rn progenies affecting the detection capability. A model linking the ²²⁰Rn emanation with the sampled ²¹²Pb activity was developed and is presented here. The model and the performed measurements show that the variation of the sampled ²¹²Pb activity can be fully explained by the variation of the local ²²⁰Rn activity concentration.     

Biomonitoring airborne parent and alkylated three-ring PAHs in the Greater Cologne Conurbation II: Regional distribution patterns

The spatial distribution of an important air pollutant class, three-ring polycyclic aromatic hydrocarbons and their derivatives (PAH-3), has been monitored for the Greater Cologne Conurbation (GCC) using pine needle as passive samplers. The GCC comprises one of the most heavily populated, trafficked, and industrialized regions in Germany. Here, 71 locations covering 3600 km² were sampled and, for the first time, isopleths maps constructed to investigate the regional variability in PAH-3 concentration and composition. The highest PAH-3 loads on needles (1000-1500 ng g⁻¹) were detected downwind of three lignite fuelled power plants, followed by Cologne City (600-700 ng g⁻¹) and smaller towns (400-600 ng g⁻¹), whereas rural and forest regions yielded PAH-3 loads of 60-300 ng g⁻¹. PAH-3 ratios facilitated source reconciliation, with high dibenzothiophene versus retene values indicating lignite combustion and high 9/(9 + 1)-methylphenanthrene ratios depicting traffic emissions in inner cities. PAH-3 ratios depended on topography and outlined the heavily industrialized Rhine Valley, demonstrating atmospheric dispersal of PAH-3.     

Present status of Rn in groundwater in Extremadura

Radon-222 was measured in groundwater sources of Extremadura (Spain), analyzing 350 samples from private and public springs, wells, and spas by liquid scintillation counting (LSC) and gamma spectrometry. The ²²²Rn activity concentrations ranged from 0.24 to 1168 Bq L⁻¹. The statistical analysis showed a log-normal distribution with a mean of (111 ± 7) Bq L⁻¹ and a median of (36 ± 3) Bq L⁻¹. A hydrogeological study revealed correlations between the activity concentration and the aquifer material's characteristics. A map of ²²²Rn in groundwater was elaborated and compared with the natural gamma radiation map for this region. About 35% of the samples showed ²²²Rn activity concentrations above the Euratom recommended limit of 100 Bq L⁻¹. Three uranium series radionuclides (²³⁸U, ²³⁴U, and ²²⁶Ra) were also assayed by alpha-particle spectrometry, estimating the annual effective dose due to the presence of these natural radionuclides in drinking water.     

A methodology for assessing the maximum expected radon flux from soils in northern Latium (central Italy)

Northern Latium (Italy) is an area where the Rn risk rate is potentially high because of the extensive outcropping of Neogene U-rich volcanics and the presence of major active tectonic lineaments. The lack of data on Rn risk rates in that area, which is undergoing major urban and industrial development, has prompted this study. It proposes a methodology to evaluate the maximum potential diffusive Rn flux from soils based on the measurement of ²²⁶Ra, ²³²Th and ⁴⁰K activities by γ-ray spectrometry, and the measurement of main soil parameters influencing the Rn emanation. This methodology provides a simple, reliable and low-cost tool for drawing up radon flux maps useful to both public planners and private individuals, who want to operate safely in the study area. The proposed methodology may also be applied to other geographic areas outside the prescribed study area.     

GIS支持的卫星图像土地利用现状分类和制图

应用卫星图像提取专题要素，综合利用多元地理信息，是克服多光谱数据在解像力和分辨率上所存在的局限性的有效途径。ＧＩＳ技术则提供多种处理功能将图像与地理信息复合，提高分类精度。分类图像数据与地形基础要素数据复合，通过彩色扫描绘图机直接绘制高质量的土地利用现状专题地图。     

Comparison of ordinary and lognormal kriging on skewed data of total cadmium in forest soils of Sweden

Spatial statistical analysis of georeferenced data of total cadmium (TCd) in forest soils of Sweden was assumed to providemore advantageous maps than traditional interpolated maps. However, 264 measurements of TCd in O-horizon of forest soils displayed skewed frequency distribution. Since atypicalobservations affect badly the variogram, outliers wereidentified, different data transformations were tested andordinary (OK) and lognormal kriging (LK) scenarios werecompared based on cross-validation. Results were comparedusing overall measures of predictors, e.g. traditionalmean squared prediction error (MSPE), mean of krigingvariances, variance ratio, median of internallystandardised residuals, and assessments of classificationaccuracy, such as percentage of correctly predictedsamples and within-class MSPE.One outlier was identified based on the absolute value of skewness of value differences less or equal to one in data pairs separated at certain lag classes. Mapping categories characterised by percentage of correct classification and within-class MSPE were found to be essential in comparison of kriging results additionally to the overall measures. In comparison of kriging methods, OK predicted high values moreaccurately and LK was more effective to predict low and mediumvalues. Thus, OK was suggested for mapping high concentration of TCd and other pollutants. Percentage of correctly predictedsamples and within-class MSPE were found to be dependent on kriging method, as well as on the number and limits of categories.