Joint Risk of Rainfall and Storm Surges during Typhoons in a Coastal City of Haidian Island, China.

Public health risks from urban floods are a global concern. A typhoon is a devastating natural hazard that is often accompanied by heavy rainfall and high storm surges and causes serious floods in coastal cities. Affected by the same meteorological systems, typhoons, rainfall, and storm surges are three variables with significant correlations. In the study, the joint risk of rainfall and storm surges during typhoons was investigated based on principal component analysis, copula-based probability analysis, urban flood inundation model, and flood risk model methods. First, a typhoon was characterized by principal component analysis, integrating the maximum sustained wind (MSW), center pressure, and distance between the typhoon center and the study area. Following this, the Gumbel copula was selected as the best-fit copula function for the joint probability distribution of typhoons, rainfall, and storm surges. Finally, the impact of typhoons on the joint risk of rainfall and storm surges was investigated. The results indicate the following: (1) Typhoons can be well quantified by the principal component analysis method. (2) Ignoring the dependence between these flood drivers can inappropriately underestimate the flood risk in coastal regions. (3) The co-occurrence probability of rainfall and storm surges increases by at least 200% during typhoons. Therefore, coastal urban flood management should pay more attention to the joint impact of rainfall and storm surges on flood risk when a typhoon has occurred. (4) The expected annual damage is 0.82 million dollars when there is no typhoon, and it rises to 3.27 million dollars when typhoons have occurred. This indicates that typhoons greatly increase the flood risk in coastal zones. The obtained results may provide a scientific basis for urban flood risk assessment and management in the study area.

Systematic Consensus Building on Disaster Mental Health Services After the Great East Japan Earthquake by Phase.

OBJECTIVE: We intended to build consensus on appropriate disaster mental health services among professionals working in the area affected by the Great East Japan Earthquake. METHODS: We focused on the first 3 months after the disaster, divided into 3 phases: immediate aftermath, acute phase, and midphase. We adopted the Delphi process and asked our survey participants (n=115) to rate the appropriateness of specific mental health services in each phase and comment on them. We repeated this process 3 times, giving participants feedback on the results of the previous round. Through this process, we determined the criterion for positive consensus for each item as having the agreement of more than 80% of the participants. RESULTS: We found that the importance of acute psychiatric care and prescribing regular medication for psychiatric patients gained positive consensus in the immediate aftermath and acute phase. Counseling and psychoeducation after traumatic events or provision of information gained consensus in the acute phase and midphase, and screening of mental distress gained consensus in the midphase. CONCLUSIONS: Higher priority was given to continuous psychiatric services in the immediate aftermath and mental health activities in later phases.

Comparison of geostatistical kriging algorithms for intertidal surface sediment facies mapping with grain size data.

This paper compares the predictive performance of different geostatistical kriging algorithms for intertidal surface sediment facies mapping using grain size data. Indicator kriging, which maps facies types from conditional probabilities of predefined facies types, is first considered. In the second approach, grain size fractions are first predicted using cokriging and the facies types are then mapped. As grain size fractions are compositional data, their characteristics should be considered during spatial prediction. For efficient prediction of compositional data, additive log-ratio transformation is applied before cokriging analysis. The predictive performance of cokriging of the transformed variables is compared with that of cokriging of raw fractions in terms of both prediction errors of fractions and facies mapping accuracy. From a case study of the Baramarae tidal flat, Korea, the mapping method based on cokriging of log-ratio transformation of fractions outperformed the one based on cokriging of untransformed fractions in the prediction of fractions and produced the best facies mapping accuracy. Indicator kriging that could not account for the variation of fractions within each facies type showed the worst mapping accuracy. These case study results indicate that the proper processing of grain size fractions as compositional data is important for reliable facies mapping.

Modeling tidal marsh distribution with sea-level rise: evaluating the role of vegetation, sediment, and upland habitat in marsh resiliency.

Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-level rise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-level rise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-level rise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-level rise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea-level rise. These results also emphasize the importance of adjacent uplands for long-term marsh survival and incorporating such areas in conservation planning efforts.

Wavelet analysis of lunar semidiurnal tidal influence on selected inland rivers across the globe.

The lunar semidiurnal influence is already known for tidal rivers. The moon also influences inland rivers at a monthly scale through precipitation. We show that, for some non-tidal rivers, with special geological conditions, the lunar semidiurnal tidal oscillation can be detected. The moon has semidiurnal tidal influence on groundwater, which will then export it to streamflow. Long time series with high frequency measurements were analysed by using standard wavelet analysis techniques. The lunar semidiurnal signal explains the daily double-peaked river level evolution of inland gauges. It is stronger where springs with high discharge occur, especially in the area of Edwards-Trinity and Great Artesian Basin aquifers and in areas with dolomite/limestone strata. The average maximum semidiurnal peaks range between 0.002 and 0.1 m. This secondary effect of the earth tides has important implications in predicting high resolution hydrographs, in the water cycle of wetlands and in water management.

Variational stereo imaging of oceanic waves with statistical constraints.

An image processing observational technique for the stereoscopic reconstruction of the waveform of oceanic sea states is developed. The technique incorporates the enforcement of any given statistical wave law modeling the quasi-Gaussianity of oceanic waves observed in nature. The problem is posed in a variational optimization framework, where the desired waveform is obtained as the minimizer of a cost functional that combines image observations, smoothness priors and a weak statistical constraint. The minimizer is obtained by combining gradient descent and multigrid methods on the necessary optimality equations of the cost functional. Robust photometric error criteria and a spatial intensity compensation model are also developed to improve the performance of the presented image matching strategy. The weak statistical constraint is thoroughly evaluated in combination with other elements presented to reconstruct and enforce constraints on experimental stereo data, demonstrating the improvement in the estimation of the observed ocean surface.

Adélie penguin foraging location predicted by tidal regime switching.

Penguin foraging and breeding success depend on broad-scale environmental and local-scale hydrographic features of their habitat. We investigated the effect of local tidal currents on a population of Adélie penguins on Humble Is., Antarctica. We used satellite-tagged penguins, an autonomous underwater vehicle, and historical tidal records to model of penguin foraging locations over ten seasons. The bearing of tidal currents did not oscillate daily, but rather between diurnal and semidiurnal tidal regimes. Adélie penguins foraging locations changed in response to tidal regime switching, and not to daily tidal patterns. The hydrography and foraging patterns of Adélie penguins during these switching tidal regimes suggest that they are responding to changing prey availability, as they are concentrated and dispersed in nearby Palmer Deep by variable tidal forcing on weekly timescales, providing a link between local currents and the ecology of this predator.

Treating children traumatized by war and Tsunami: a comparison between exposure therapy and meditation-relaxation in North-East Sri Lanka.

BACKGROUND: The North-Eastern part of Sri Lanka had already been affected by civil war when the 2004 Tsunami wave hit the region, leading to high rates of posttraumatic stress disorder (PTSD) in children. In the acute aftermath of the Tsunami we tested the efficacy of two pragmatic short-term interventions when applied by trained local counselors. METHODS: A randomized treatment comparison was implemented in a refugee camp in a severely affected community. 31 children who presented with a preliminary diagnosis of PTSD were randomly assigned either to six sessions Narrative Exposure Therapy for children (KIDNET) or six sessions of meditation-relaxation (MED-RELAX). Outcome measures included severity of PTSD symptoms, level of functioning and physical health. RESULTS: In both treatment conditions, PTSD symptoms and impairment in functioning were significantly reduced at one month post-test and remained stable over time. At 6 months follow-up, recovery rates were 81% for the children in the KIDNET group and 71% for those in the MED-RELAX group. There was no significant difference between the two therapy groups in any outcome measure. CONCLUSION: As recovery rates in the treatment groups exceeded the expected rates of natural recovery, the study provides preliminary evidence for the effectiveness of NET as well as meditation-relaxation techniques when carried out by trained local counselors for the treatment of PTSD in children in the direct aftermath of mass disasters. TRIAL REGISTRATION: ClinicalTrials.gov Identifier:NCT00820391.

Tsunami-related injury in Aceh Province, Indonesia.

The Asian tsunami, of December 2004, caused widespread loss of life. A series of surveys were conducted to assess tsunami-related mortality and injury, risk factors, care seeking and injury outcomes. Three surveys of tsunami-affected populations, in seven districts of Aceh province, were conducted between March and August 2005. Surveys employed a two-stage cluster design and probability proportional to size sampling methods. Overall, 17.7% (95% confidence interval (CI)=16.8-18.6) of the population was reported as dead/missing1 and 8.5% (95% CI=7.9-9.2) had been injured. Odds of mortality were 1.41% (95% CI=1.27-1.58) times greater in females than in males; risk of injury was opposite, with an odds of injury of 0.81 (95% CI=0.61-0.96) for females in comparison to males. Mortality was greatest among the oldest and young population sub-groups, and injuries were most prevalent among middle-aged populations (20-49). An estimated 25,572 people were injured and 3682 (1.2%) suffered lasting disabilities. While mortality was particularly elevated among females and among the youngest and oldest age groups, injury rates were the greatest among males and the working-age population, suggesting that those are more likely to survive the tsunami were also more likely to be injured.

Mental health and the psychosocial consequences of natural disasters in Asia.

This article presents an overview of natural disasters in Asia, as well as mental disorders and psychosocial interventions related to disasters. Although most of the top ten worst natural disasters occurred in Asia over the past century, little is known about the mental health and psychosocial aspects. After the tsunami incident in 2004, research reports in international journals related to Asian disasters have been growing. The prevalence rate of post-traumatic stress disorder related to natural disasters is currently between 8.6% and 57.3% depending on assessment methodologies, instruments and timing. Cognitive behaviour therapy has been found to be effective with Asian survivors but needs to be adapted for cultural and local sensitivities. Further research is needed in the areas of epidemiology for mental disorders and suitable psychosocial interventions for disaster survivors in Asia.

Psychological wellbeing of survivors of the tsunami: empowerment and quality of life.

OBJECTIVE: To compare the empowerment and the quality of life of individuals before and after receiving the psychological services and support interventions. STUDY DESIGN: This quasi-experimental research had two hypotheses: 1) the survivors gained empowerment, and 2) the survivors experienced improvement in their quality of life, after receiving the interventions. SETTING: Krabi province of Thailand. STUDY POPULATION: 593 survivors of the Tsunami on 26 December 2004. MATERIAL AND METHOD: The instrument to assess empowerment was modified from Miller, while the instrument to assess quality of life was WHO-BREF. RESULTS: After the intervention, the overall mean of empowerment was at the maximum level, and revealed an increased percentage of the quality of life at a good level in all four domains. The level of the psychological domain was the highest. CONCLUSION: The sample showed a significant increase in both empowerment and quality of life (p < 0.001). The findings support the hypotheses.

KAMEDO Report No. 91: 2004 tsunami disaster in Asia--home transport and emergency care in Sweden.

This is a descriptive report of the Swedish authorities' responses to the tsunami that affected Southeast Asia in December 2004. The main focus is the care of survivors and the injured during their transportation from Thailand and their return to Sweden. The psychological and physical after-effects also are presented based on a poll conducted one year after the tsunami.