A Framework for Risk Assessment

AbstractRisk is a composite concept: it is the product of the probability that an event will take place (usually that something will go wrong) and the (negative) effect it will have if it does take place. In general, risk abatement within engineering is concerned with minimising both components, with the balance of effort being determined by cost-effectiveness. Risk assessment is the action (or inaction) taken to address the risk issues identified and evaluated in the assessment and analysis efforts, generally with a view to containing or reducing the risk. While the private sector may enhance management by controlling risk, it is more difficult for the public sector to do the same with their shareholders (population), as the risks relate to other sectors, mainly infrastructure. This paper presents a risk assessment framework to address the multiple goals of disaster risk reduction in order to be coherent with the planning of social and economic development, providing a design concept for the development of risk management policies. The legal basis for risk reduction policies is critical for transparent decision-making and allocating public funding for disaster mitigation. Risk management actually takes place on three different levels: (1) Before the disaster – planning, drills and communication (2) During the event – communication, operations associated with the operation of existing systems (3) After the disaster – assessment and reconstruction. Lessons learnt for starting all over

Assessing and Measuring Resilience

AbstractConcepts of resilience take two broad forms: (1) hard resilience: the direct strength of structures or institutions when placed under pressure, such as increasing the resilience of a structure through specific strengthening measures to reduce their probability of collapse. (b) soft resilience: the ability of systems to absorb and recover from the impact of disruptive events without fundamental changes in function or structure, which depend on the flexibility and adaptive capacity of the system as a whole, rather than simply strengthening structures or institutions in relation to specific stresses, as in the hard resilience approach. However, there are three possibilities in response to threats of disturbance: (a) Resistance and maintenance, which is characterized by resistance to change. A human system of this type would do its utmost to avoid change and would typically deny that a problem exists. (b) Change at the margins, characterized by acknowledgement of the problem, discussion of the implications, and, hopefully, a clear acknowledgement that the present system is not sustainable and that change is needed. (c) Openness and adaptability, an approach reduces vulnerability by having a high degree of flexibility. Its key characteristic is a preparedness to adopt new basic operating assumptions and institutional structures. Once the resilience options have been identified to meet the vulnerability of a system, it is necessary to compare the degree of resilience that the different alternatives may offer. The different concepts are examined to propose both a qualitative and a possible quantification of the degree of resilience that may be achieved by the different measures proposed for implementation

Technological Advances in Wireless Sensor Network Systems for Urban Drainage Monitoring

Urban drainages are important for evacuation of waste water in cities. It helps for the smooth running of the daily activities in the city and prevents proliferation of diseases. Drainage systems and construction methods have not evolved much in the past years. Due to population growth, urbanization and climatic changes, our urban drainages have become inefficient. Localized heavy rainfall causes overflow of drains that lead to floods resulting in major infrastructural damages and loss of lives. Obstruction due to solid waste prevents effective waste water evacuation. In this paper existing drainage monitoring systems are identified and their monitoring methods and technologies are analysed. Current drainage water monitoring methods such as the Rational method, the Modified Rational method, the SCS Runoff method, the Saint-Venant equation and the Manning’s equation are not reliable and only provide estimated value for peak discharge and mean water velocity. Wireless sensor network systems for monitoring drains and rivers in different regions such as Birmingham, Brazil, Philippines and Mississippi are thoroughly discussed. Wireless sensors and microprocessor platforms that may be used for the urban drainage monitoring are evaluated. A systematic review of the research challenges for real-time monitoring of urban drainages is carried out. Furthermore, possible solutions that use advanced sensor technologies to detect overflow and obstruction in urban drainages are analysed. Indeed this paper provides a comprehensive assessment of technological advances in urban drainage monitoring systems. Keywords: wireless sensor networks, urban drainage monitoring, water flow monitoring, overflow detection, obstruction detectio

Submarine groundwater springs are characterized by distinct fish communities

The inflow of terrestrial groundwater into the ocean is increasingly recognized as an important local source of nutrients and pollutants to coastal ecosystems. Although there is evidence of a link between fresh submarine groundwater discharge (SGD)‐derived nutrients and primary producer and primary consumer abundances, the effects of fresh SGD on the productivity of higher trophic levels such as ichthyofaunal communities remain unclear. To further investigate this relationship, we sampled three sites inside a coral reef lagoon in Mauritius: One site entailing six distinct groundwater springs, a site highly influenced by freshwater influx through the springs, and a strictly marine control site. Using remote underwater video surveys, we found that fish abundances were significantly higher at the groundwater springs than at the other two sampling sites.Principal component analyses showed that the springs and the spring‐influenced part of the lagoon were best described by elevated water nutrient loadings, whereas the control site was characterized by higher water salinity and pH. Macroalgae cover was highest at the control site and the springs. Herbivores and invertivores dominated the fish community at the springs, in contrast to generalists at the control site. At the spring‐influenced site, we mainly encountered high coral/turf algae cover and high abundances of associated fish feeding groups (territorial farmers, corallivores). Our results provide evidence of a fresh SGD‐driven relationship between altered hydrography and distinct fish communities with elevated abundances at groundwater springs in a coral reef lagoon. These findings suggest that the management and assessment of secondary consumer productivity in tropical lagoons should take into account the effects of groundwater springs

Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge : IAEA-UNESCO intercomparison exercise at Mauritius Island

Author Posting. © The Author(s), 2011. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Environmental Radioactivity 104 (2012): 24-45, doi:10.1016/j.jenvrad.2011.09.009.Submarine groundwater discharge (SGD) into a shallow lagoon on the west coast of Mauritius Island (Flic-en-Flac) was investigated using radioactive (3H, 222Rn, 223Ra, 224Ra, 226Ra, 228Ra) and stable (2H, 18O) isotopes and nutrients. SGD intercomparison exercises were carried out to validate the various approaches used to measure SGD including radium and radon measurements, seepage-rate measurements using manual and automated meters, sediment bulk conductivity and salinity surveys. SGD measurements using benthic chambers placed on the floor of the Flic-en-Flac Lagoon showed discharge rates up to 500 cm/day. Large variability in SGD was observed over distances of a few meters, which were attributed to different geomorphological features. Deployments of automated seepage meters captured the spatial and temporal variability of SGD with a mean seepage rate of 10 cm/day. The stable isotopic composition of submarine waters was characterized by significant variability and heavy isotope enrichment and was used to predict the contribution of fresh terrestrially derived groundwater to SGD (range from a few % to almost 100 %). The integrated SGD flux, estimated from seepage meters placed parallel to the shoreline, was 35 m3/m day, which was in a reasonable agreement with results obtained from hydrologic water balance calculation (26 m3/m day). SGD calculated from the radon inventory method using in situ radon measurements were between 5 and 56 m3/m per day. Low concentrations of radium isotopes observed in the lagoon water reflected the low abundance of U and Th in the basalt that makes up the island. High SGD rates contribute to high nutrients loading to the lagoon, potentially leading to eutrophication. Each of the applied methods yielded unique information about the character and magnitude of SGD. The results of the intercomparison studies have resulted a better understanding of groundwater-seawater interactions in coastal regions. Such information is an important pre-requisite for the protection management of coastal freshwater resources.The financial support provided by the IOC and IHP of UNESCO for travel arrangements, and by the IAEA’s Marine Environment Laboratories for logistics is highly acknowledged. MAC and MEG were supported in part by the US National Science Foundation (OCE-0425061 and OCE-0751525). PPP acknowledges a support provided by the EU Research & Development Operational Program funded by the ERDF (project No. 26240220004), and the Slovak Scientific Agency VEGA (grant No. 1/108/08). The International Atomic Energy Agency is grateful to the Government of the Principality of Monaco for support provided to its Marine Environment Laboratories

Estimating Rainfall in Rodrigues by Geostatistics: (A) Theory

This paper introduces the geostatistical method. Originally devised to treat problems that arise when conventional statistical theory is used in estimating changes in ore grade within a mine, it is, however, an abstract theory of statistical behaviour that is applicable to many circumstances in different areas of geology and other natural sciences. Using rainfall at Réduit and at Citronelle as examples, the key concepts that are explained are the regionalised variable, the variogram and the kriging procedure. A list of fields where the method has been applied is given. What is common to these different applications is the regionalised variable, function of space/time with some kind of correlation in the spatial distribution of these magnitudes. Once the link of a parameter with space or time has been established or suspected, a geostatistical analysis may be tried.Keywords: regionalised variable, variogram, semivariance, krigin

Suitability of dam sites in Mauritius

Sites where dams/reservoirs have been proposed in Mauritius are listed in Table 1. In many of these places,  detailed investigations have been carried out, only to be shelved for some reason or other. Other dams have  been constructed, sometimes after a sketchy desk study investigation, simply because of the urgency of  water supply or because of lack of appropriate expertise. It is proposed here to look at a few dams (proposed or built), notably because of findings during investigations or during performance afterwards

Curbing air pollution in Paris : a comparative analysis of the ‘Low Emission Zones’

International audienc