Improving conveyance of uncertainties in the findings of the IPCC

Authors of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) received guidance on reporting understanding, certainty and/or confidence in findings using a common language, to better communicate with decision makers. However, a review of the IPCC conducted by the InterAcademy Council (2010) found that “the guidance was not consistently followed in AR4, leading to unnecessary errors . . . the guidance was often applied to statements that are so vague they cannot be falsified. In these cases the impression was often left, quite incorrectly, that a substantive finding was being presented.” Our comprehensive and quantitative analysis of findings and associated uncertainty in the AR4 supports the IAC findings and suggests opportunities for improvement in future assessments.     

Effects of degree of saturation on shallow landslides triggered by rainfall

The empirical rainfall threshold concept and the physical-based model are two commonly used approaches for the assessment of shallow landslides triggered by rainfall. To investigate in detail the rainfall-triggered shallow landslides, many physical-based models coupling the infinite slope stability analysis with the rainfall infiltration modeling in variably saturated soil were developed. However, in those physical-based shallow landslide models, the unit weight and the unsaturated shear strength were assumed constant rather than depending on the degree of saturation. In this study, the effects of the unit weight and the unsaturated shear strength as function of degree of saturation on rainfall-triggered shallow landslides are examined. Several designed scenarios and a real case scenario are used to conduct the examinations. The results show that not only the occurrence of shallow landslides but also the failure depth and the time to failure could be misassessed if the influences of degree of saturation on the unit weight and the unsaturated shear strength are neglected.     

EM and GPR investigations of contaminant spread around the Hoc Mon waste site,Vietnam

This paper is presenting the results from near-surface geophysical surveys near the waste site of Hoc Mon in southern Vietnam where leachate contamination has been recognized at the surface. Using EM and GPR surveys, we were able to determine the lateral extent of a contaminated area of high electrical conductivity and have identified channels that concentrate the contaminant flow. The simple relationship between the electrical resistivity and the leachate concentration is suggested and estimated the in situ leachate concentration from the inversion of the EM data; values are as high as 40%. Thanks to a permeability barrier leachate flow is confined to the shallow subsurface, making it easier to apply possible site remediation projects.     

Global ionosphere map constructed by using total electron content from ground-based GNSS receiver and FORMOSAT-3/COSMIC GPS occultation experiment

Effects of rapidly changing ionospheric weather are critical in high accuracy positioning, navigation, and communication applications. A system used to construct the global total electron content (TEC) distribution for monitoring the ionospheric weather in near-real time is needed in the modern society. Here we build the TEC map named Taiwan Ionosphere Group for Education and Research (TIGER) Global Ionospheric Map (GIM) from observations of ground-based GNSS receivers and space-based FORMOSAT-3/COSMIC (F3/C) GPS radio occultation observations using the spherical harmonic expansion and Kalman filter update formula. The TIGER GIM (TGIM) will be published in near-real time of 4-h delay with a spatial resolution of 2.5° in latitude and 5° in longitude and a high temporal resolution of every 5 min. The F3/C TEC results in an improvement on the GIM of about 15.5%, especially over the ocean areas. The TGIM highly correlates with the GIMs published by other international organizations. Therefore, the routinely published TGIM in near-real time is not only for communication, positioning, and navigation applications but also for monitoring and scientific study of ionospheric weathers, such as magnetic storms and seismo-ionospheric anomalies.     

Evaluation of bank filtration as a pretreatment method for the provision of hygienically safe drinking water in Norway: results from monitoring at two full-scale sites

Two case studies were carried out in central Norway in order to assess the performance of bank filtration systems in cold-climate fluvial aquifers relying on recharge from humic-rich surface waters with moderate microbial contamination. Three municipal wells and two surface-water sources at operative bank filtration systems were monitored for naturally occurring bacteriophages, fecal indicators, natural organic matter (NOM) and physico-chemical water quality parameters during a 4-month period. Aquifer passage effectively reduced the microorganism and NOM concentrations at both study sites. Bacteriophages were detected in 13 of 16 (81%) surface-water samples and in 4 of 24 (17%) well-water samples, and underwent 3 ± 0.3 log₁₀ reduction after 50–80-m filtration and 20–30 days of subsurface passage. NOM reductions (color: 74–97%; dissolved organic carbon: 54–80%; very hydrophobic acids: 70%) were similar to those achieved by conventional water-treatment processes and no further treatment was needed. Both groundwater dilution and sediment filtration contributed to the hygienic water quality improvements, but sediment filtration appeared to be the most important process with regard to microbial and NOM reductions. A strengths-weaknesses-opportunities-threats analysis showed that bank filtration technology has a high potential as a pretreatment method for the provision of hygienically safe drinking water in Norway.     

420芦山地震峡口滑坡监测数据分析

基于420芦山地震前后获取的峡口滑坡监测数据,对地震发生时峡口滑坡地下水位、深部位移及地表位移变化情况进行了分析,结果表明：（1）芦山地震前,峡口滑坡地下水位出现持续异常上升,涨幅在1m以上, 4月20日即芦山地震发生当日,地下水位达到峰值,震后,地下水位开始迅速下降,降幅在1.5m左右; （2）芦山地震发生当天,受芦山地震的影响,滑坡深部发生了一次大于1mm的位移,其后恢复基本稳定的状态。利用R/S分析方法对峡口滑坡稳定性进行分析,受芦山地震影响, 4月份峡口滑坡的Hurst指数明显有所下降,说明滑坡的稳定性有所降低。但总体上滑坡的Hurst指数均大于0.5,说明滑坡一直处于稳定状态。     

Why relatively fewer people died? The case of Bangladesh’s Cyclone Sidr

Cyclone Sidr, a Category IV storm, struck the southwestern coast of Bangladesh on November 15, 2007 killing 3,406 people. Despite a similar magnitude, Sidr claimed far fewer lives than Cyclone Gorky, also a Category IV storm, which struck Bangladesh in 1991 causing an estimated 140,000 fatalities. The relatively low number of deaths experienced with Sidr is widely considered the result of Bangladesh government’s efforts to provide timely cyclone forecasting and early warnings, and successful evacuation of coastal residents from the projected path of Cyclone Sidr. Using information collected from both primary and secondary sources, this study identified several other reasons for the unexpectedly lower mortality associated with Cyclone Sidr relative to Cyclone Gorky. Fewer casualties may be attributed to a number of physical characteristics of Cyclone Sidr, such as duration of the storm and storm surge, landfall time and site, varied coastal ecology, and coastal embankment. This article recommends improvements to the cyclone warning systems, establishment of more public cyclone shelters, and implementation of an education campaign in coastal areas to increase the utilization of public shelters for future cyclone events.     

Monitoring of wastewater percolation in unsaturated sandy soil using geoelectrical measurements at Gabal el Asfar farm,northeast Cairo,Egypt

The use of wastewater for irrigation in sandy soil increases the pollution risk of the soil and may infiltrate to the shallow groundwater aquifer. In such environment, some important parameters need to be obtained for monitoring the wastewater in the unsaturated zone over the aquifer. These parameters include clay content, heterogeneities of the upper soils, depth to the aquifer and the variations of groundwater quality. In the present work, the efficiency of DC resistivity method in forms of 1-D and 2-D measurements was studied for wastewater monitoring in the Gabal el Asfar farm, northeast of Cairo, Egypt. Forty-one Schlumberger soundings (VES) were performed then followed by three pole-dipole 2-D profiles along some considered regions within the area. The resistivity measurements were integrated with the boreholes, hydrogeological and hydrochemical (surface and groundwater samples) information to draw a clear picture for the subsurface conditions. The obtained results were presented as cross sections and 3-D visualization to trace the clay intercalations within the unsaturated zone. In addition, a vulnerability map was created using the obtained results from 1-D Schlumberger survey and confirmed with the 2-D resistivity profiling. The obtained results have shown that the 2-D resistivity imaging technique is a powerful tool for mapping the small-scale variability within the unsaturated zone and the wastewater infiltration. However, limitations of resistivity techniques were observed in the area with limited resistivity contrast such as thin clay layers with brackish water background. Under that condition, the measured pattern of resistivity distributions depends on the applied electrode array, electrode spacing and using the available geological information during the inversion process.     

PMODTRAN: a parallel implementation based on MODTRAN for massive remote sensing data processing

MODerate resolution atmospheric TRANsmission (MODTRAN) is a commercial remote sensing (RS) software package that has been widely used to simulate radiative transfer of electromagnetic radiation through the Earth's atmosphere and the radiation observed by a remote sensor. However, when very large RS datasets must be processed in simulation applications at a global scale, it is extremely time-consuming to operate MODTRAN on a modern workstation. Under this circumstance, the use of parallel cluster computing to speed up the process becomes vital to this time-consuming task. This paper presents PMODTRAN, an implementation of a parallel task-scheduling algorithm based on MODTRAN. PMODTRAN was able to reduce the processing time of the test cases used here from over 4.4 months on a workstation to less than a week on a local computer cluster. In addition, PMODTRAN can distribute tasks with different levels of granularity and has some extra features, such as dynamic load balancing and parameter checking.