Coping with Extreme Floods using Karst Caves in Limestone Areas in the Red River Basin, Viet Nam

Tinh Dang Quang1, Tripathi Nitin Kumar2* and Silver Marshall L.3

Changing hydrologic conditions caused by upstream development in the Red River Basin of Viet Nam and by changing global and regional climate patterns , extreme flood events are expected to occur in the future with increasing frequency and with higher intensity. Constraints in costs and lands make it prohibitive to increase the height of the existing dyke system in the Red River Delta. These constraints call for new non-structural methods to reduce the severity and magnitude of floods, using the special physical conditions of the River Basin. One such method is the use of karst caves in limestone areas to cope with extreme flood events by storing excess flood waters and gradually releasing the waters into ground water aquifers in a controlled and calculated manner. This paper examines the proposed new flood control measures to use groundwater flood retention of the extensive pervious karstic limestone formation in the study area. In order to support this new concept of fighting against extreme floods, known as ‘flood karst method’, hydraulic modeling is extensively used to study different flood scenarios to identify possible options for decision-making. These options are derived from the studies on how best to combine the use storage of existing and potential surface water storage and underground retention facilities to cope with excess storm waters of extreme flood events. Finally, on the basis of the simulation of possible contributions by the facilities available, namely the Hoa Binh Reservoir, the Karst caves, the flood diversion works and proposed emergency spillways, a set of operation procedures was recommended for adoption to minimize impacts of extreme flood events.

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Preliminary Seismic Assessment of Existing Reinforced Concrete Framed Buildings

Kojouri S. J., Noorzaei J.1, 2, Abang A.A.A. , Jaafar M.S.1 and Hejazei Farzad 1, 2

The damages of structures during recent earthquakes all over the world have demonstrated the need for a real time seismic assessment method, which will be capable of predicting the vulnerability of buildings to prevent collapse during earthquake. This study demonstrates the development of a computer program which is based on the guidelines given by earthquake resistance code, FEMA 310. Comparison against other guidelines such as New Zealand, Eurocode 8, SERC (USA) and UNIDO show that FEMA 310 is more realistic on assessment of existing buildings. Buildings are evaluated either in terms of Life Safety (LS) or Immediate Occupancy (IO) performance level. This paper deals with development of a numerical tool to assess the ability of an existing building to reach an adequate level of performance related to the life safety of its occupants. The program can be used for seismic evaluation of buildings and can be applied consistently to a rather wide range of regular buildings. The results of the developed program were compared with manual computation. The applicability of the program code has been demonstrated by analyzing four reinforced concrete residential buildings of three, four, six and eight story heights.

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Psychosocial and Mental Health Support Services in Fire Disasters in India: A Qualitative Analysis

Satapathy Sujata

Fire accidents in buildings across India have caused extensive loss of life, limbs and property in the last four decades. Fires are more of psychosocial and personal phenomena rather than just physio-chemical phenomena. In last two decades, disaster psychosocial care and mental health services in India have seen a sea change in terms of approach, methodology of assessment of needs, service delivery, monitoring and evaluation of the community based programmes. This paper attempts to compile data on major fire disasters across India and the profile of psychosocial care services extended to the victims. This analysis also reveals that the need of mental health services for the victimized families was either ignored or overlooked or marginalized in most of the incidents. This also aims to do a qualitative analysis of the varied needs of fire victims (primary and secondary victims), unfolds the challenges faced by the service providers and seeks the urgent attention of care providers and other stakeholders to take up the task.

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Asteroid Impact – the Ultimate Disaster

Grandl Werner

The number of known Near Earth Objects (NEOs), such as asteroids and comet nuclei has increased continuously within the last decades. It is time to get serious about detecting and deflection techniques to protect the planet Earth (and the moon) from future impacts by hazardous NEOs.

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Seismic Hazard Analysis from a Bayesian Probabilistic Perspective

Yuen Ka Veng* and Mu He Qing

In this paper, seismic hazard analysis is performed from a Bayesian perspective. First, by using historical seismic records, the relationship between peak ground acceleration and other important factors, such as magnitude of earthquake and hypocenter-to-site distance, are developed. Numerous studies were devoted to empirical relationship using the magnitude of earthquake, the site-to-fault distance and the site foundation properties. In this study, the Bayesian approach is utilized to investigate the suitable form of empirical formula. It is obvious that a more complicated relationship (i.e. a formula with more free parameters) possesses smaller fitting error for a given set of data. However, this does not imply that the complicated relationship is more realistic since over-fitting may occur when the relationship has too many free parameters. The Bayesian model class selection method is used to identify the most suitable relationship among all the candidate relationships. The plausibility of each candidate relationship is evaluated for a database of strong-motion records, obtained from the China Earthquake Data Center. The most plausible relationship is the one with the highest plausibility. It is robust since it has balance between the data fitting capability and the sensitivity to noise. It turns out that the most plausible relationship is simpler than the well known Boore-Joyner-Fumal seismic attenuation model. Parametric uncertainty is also quantified by the Bayesian probabilistic methodology. The most plausible predictive formula provides a reliable basis for peak ground acceleration estimation. With the most plausible predictive formula and the uncertainty of the coefficients, Monte Carlo simulation can be performed to estimate the peak ground acceleration of a site and its uncertainty.

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Developing a Rapid Field based Approach for Non Specialists to indentify Landslide Prone Areas

Baban Serwan M. J.

Identifying and managing landslide prone areas are critical for planning preventative measures to curtail the losses that can be induced by these mass wasting events. This task is often handled by field officers with little background in geosciences, hence it is essential to assist these officers and provide them with practical and simple field based tools to correctly identify unstable areas. This research developed a field based inventory for non specialists to identify areas prone to landslides. The inventory was tested in the field and produced very encouraging results.

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Heavy Snowfall by Orography and Wind Shift in Cold Front Crossing Korean Eastern Coast

Choi Hyo*, Choi Doo Sun1 and Choi Mi Sook2

Using a 3D-non-hydrostatic, numerical Weather Research & Forecasting Model (WRF) version 2.2 with FNL initial data to the model, a numerical simulation of heavy snowfall caused vast economical loss from destruction of houses and traffic interruption at Gangneung city in the coastal region of Korea has been undertaken from 00 UTC, January 13 through 12 UTC, January 15, 2003. Before snowfall occurrence in the coastal region on January 13, a northwesterly wind of 3 to 6 m/s prevailed in the study area before cold front passage under the influence of a high pressure system over northeastern China north of the Korean peninsula and a low pressure centered over the northeastern part of Japan. When snowfall occurred in Gangneung, the prevailing synoptic scale northwesterly wind changed to a north or north northeasterly wind at greater than 5 m/s on the coast and greater than 10m/s over the open sea after cold front passage. The northeast to northerly onshore wind became an upslope wind in combining with the sea-valley wind and was directed toward the top of Mt. Taegulyang (alt. 896 m) located west of the city. This upslope wind lifted moisture transported from the eastern sea along the eastern slope of the mountain toward the top and resulted in condensation into cloud consisting of liquid water or snow flakes. Simul-taneously, cold northwesterly winds from north-western China moved down along the eastern slope of the mountain toward Gangneung and prevented further intrusion of the easterly upslope wind. This forced moisture to rise toward the mountain top and western basin, resulting in the formation of a thick layer of cloud from a height of 50 m to 2.8 km from the western basin of the mountain eastward towards the open sea. The cloud base along the eastern slope and at 50 m height over the city was below 00C in ambient air temperature and -80C at a height of 900m near the top of the mountain and consisted of both super saturated water droplets and ice particles. As a result, a maximum rainfall (snowfall) amount of 149 mm/3hr (19.8 cm) with accumulated snow amount of 36.8 cm was recorded in Gangneung. A rain band was located in the same area as a band of snowfall and directly coincided with the area of relative humidity greater than 95 %. Areas of total cloud mixing ratio greater than 0.01 g/kg and relative humidity greater than 95 % in vertical profiles closely matched cloud areas on GMS-IR satellite imagery and also on radar images. The proportion of snowfall to rainfall was approxi-mately 1 to 10. Under the influence of a north-westerly wind parallel to the coast, moisture advection became very weak, resulting in either a small amount of snow or none at all on the coast.

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Association between Cosmic ray Variations and Total Ozone

Joshi Indira Sudhir

Annual mean total ozone data for three stations Alma-Ata(43˚ 14’N, 76˚ 56’E; 847M msl); New Delhi(28˚ 35’N ,77˚ 12’E ; 216M msl) and Kodaikanal (10˚14’N; 77˚28’E;2339M msl) are analysed Vis-à-vis cosmic Ray Variation of Alma Ata for the period 1973-1993 and cosmic Ray variation of Calgary (51.05’N,11408’W;1128M msl), Canada. The relation between intensity of cosmiray variation and Total ozone has also been studied.

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