Ecological impacts of flood mitigation and drainage in coastal lowlands / Impactos ecológicos de la mitigación de inundaciones y del drenaje en tierras bajas costeras

There are increasing development pressures on the south-eastern Australian coastal lowlands. The climate of these coastal floodplains provides favourable conditions for crop and pasture growth but it also causes frequent flooding and propagates the effects of land use changes into streams rapidly. This paper explores the interactions between hydrology, drainage and flood mitigation, acid sulfate soils and their ecological impacts in south-eastern Australia, and examines government response to the ecological emergencies generated and the institutional impediments to addressing them

De L' evaluation a la gestion des risques : La vulnerabilité en question / From hazards evaluation to their management : vulnerability in question

L'article invite le lecteur a reflechir sur la notion de vulnerabilite indissociable de toute approche du risque. Cette question concerne les regions cotieres, mais de maniere generale tout type de region exposee aux menaces naturelles. Plusieurs exemples, issus de travaux recemment realises dans le domaine des sciences sociales, illustrent l'interet des etudes de vulnerabilite (AU)

Storm waves in Canadian waters : A major marine hazard

In this paper, an overview of storm waves associated with intense weather systems affecting the east and west coasts on Canada is presented. The paper presents the wave climatology of the east and west coasts in terms of the 100-year significant and maximun wave heights and further analyses the directional distribution of wave heights at selected locations in the Canadian east and west coasts offshore. The paper also analyses wave hazards associated with storm waves in the Beaufort Sea as well as the Canadian Great Lakes region. A section on ocean wave modelling provides a brief history of the development of ocean surface wave models and its present status. The paper further considers the impact of climate change scenarios on wave hazards and finally examines mitigation measures in terms of wave products available from operational models and related wave climatology.(AU)

Storm surges in Canadian waters

Storm surges in various Canadian waters are reviewed. Following a brief discussion of the weather systems that cause surges in Canadian coastal and inland waters, the mathematical formulations to describe the development of storm surges are given. In reviewing storm surges in the different Canadian waters, particular attention is given to describe the influence of the presence of sea ice on surge development and the impact of shallow coastal areas, where the coastline configuration is itself changed by the surge, on inland penetration of the east and west coasts, the Beaufort Sea, the Gulf of St. Lawrence and the St. Lawrence estuary, Hudson Bay and the Great Lakes.(AU)

Case studies of tsunami countermeasure considering coastal environment

This tsunami produceda rumup of 31.7m, the highest in Japan in this country. It caused a severe damage to Okushiri Island and Hokkaido. The details of the tsunami and damage were surveyed by many researchers and will be published elsewhere (for example, Satake and Imamura). The present paper aims to summarize some of these results in order to show the major characteristics of the tsunami and damage to the readers who have no access to references written in Japanese (AU)

On the use of NOAA's storm surge model, SLOSH, in managing coastal hazards - The experience in Puerto Rico

A numerical-dynamic, tropical storm surge model, SLOSH (Sea, Land, and Overland Surges from Hurricanes), was originally developd for real-time forecasting of hurricane storm suges on continental shelves, across inland water bodies and along coastlines and for inland routing of water - either from the sea or from inland water bodies. The model is two-dimensional, covering water bodies and inundated terrain. In the present version available at the University of Puerto Rico a curvilinear, polar coordinate grid scheme is used. The grid cells are approximately 3.2 x 3.2 km in size. The model has been used ina revision of all coastal Flood insurance Rate Maps (FIRM) for Puertto Rico and the U.S. Virgin Islands, and in hurricane evacuation studies. The FIRM's since they are based on the 100 year stillwater elevation, are also used by the state Planning Board for regulatory purposes. The hurricane evacuation studies are used by emergency planners and personnel to assign shelters, escape routes, and delimit coastal zones that need to be evacuated during a hurricane threat. Recently the acquisition of data from hurricane Hugo has allowed the first comparison of model results and observations for Puerto Rico and the other islands (AU)

El adiestramiento y la educación en el plan de contingencia para la costa oriental del Lago de Maracaibo, Venezuela

La producción de petróleo en la Costa Oriental del Lago de Maracaibo ha ocasionado un hundimiento hasta 5.30 metros lo cual, aunado a la morfología del área (costas bajas y anegadizas), condujo a la necesidad de proteger de las aguas del lago, vidas humanas e instalaciones mediante la construcción de diques costaneros. Dichos diques protegen alrededor de 62.000 personas, así como las instalaciones para producir o transportar 1.500.000 barriles de petróleo diarios, es decir, cerca del 60 por ciento de la producción del país. Estudios recientes en esta zona de moderada amenaza sísmica han indicado la posibilidad de una falla de dichos diques debido a la licuación de los suelos de fundación, originada por un sismo de determinadas características, lo que podría ocasionar la inundación de las áreas por debajo del nivel del lago. En 1988 se inició la implantación de medidas de prevención (desincentivar el desarrollo de tierras por debajo del nivel del lago), medidas de mitigación (refuerzo de los diques y mejora de los suelos de fundación) y la preparación de un plan de contingencia, conocido como el Plan COLM, orientado a minimizar el impacto social de una falla no controlable los diques costaneros. Entre los aspectos más relevantes del Plan COLM destacan los programas de adiestramiento y de educación, habiéndose efectuado a la fecha más de un centenar de presentaciones, seminarios y talleres que cubren aspectos tales como: Administración de Desastres, Medicina de Desastres, Comunicación en Situaciones de Crisis, así como simulacros de evacuación en un hospital, tres clínicas y tres escuelas. El programa educacional, preparado en colaboración con las autoridades educacionales nacionales y regionales, ha consistido en cuatro sesiones de un primer taller para más de 700 educadores que cubren una población estudiantil de más de 18.000 alumnos (AU)

New technology for improved storm risk assessment in the Caribbean

The effects of tropical storms on caribbean island satates are reviewed and their potential for destruction from coastal flloding and extreme winds are highlighted in the context of sea-level rise and increasingly dense coastal development. the Caribbean disaster mitigation project (CDMP) is applying new tecnology in modelling these effects. The model used by CDMP relies on a generic dabase structure using available 'off the shelf' data sources such as satellite imagery and the National Hurricane Center dabase.The model provides probable maximun values for wind at surface and for still-water elevation and wave height at the coastline.Applications in the areas of land use planning design of coastal works and disaster preparedness are presented. The results of this model compare favourably to those of existing storm surge models such as the WHAFIS model of the Federal Emergency Management Agency (FEMA) and the SLOSH model of the National Oceanographic and Atmospheric Agency (NOAA) (AU)

Expected tsunami amplitudes and currents along the North American coast for cascadia subduction zone earthquakes

Tsunamis are numerically modeled using the nonlinear shallow-water equations for three hypothetical Cascadia subduction zone earthquakes. Maximun zero-to-peak tsunami amplitudes and currents are tabulated for 131 sites along the North American coast. Earthquake source parameters are chosen to satisfy known subduction zone configuration and thermal constraints. These source parameters are used as input to compute vertical sea-flood displacement. The three earthquakes modeled are moment magnitude 8.8, 8.5 and 7.8. Maximun zero-to peak tsunami amplitude for the Mw=8.8 earthquake is near 6 m normal to the fault break and maximum current is near3.5 m/s. Maximum amplitudes decrease by about one-half north and south of the fault break in the source region. Tsunami amplitudes vary along yhe Alaskan coast from less than 0.5 to 1.6 m. The modeled amplitudes for the Mw=8.8 quake decrease to less than 0.4 m south of Point Conception, CA. The Mw=7.8 earthquake generates a tsunami with a maximum amplitude of less than 1 m normal to the source (AU)

Seismotectonic studies of the coastal areas of India, Pakistan, Bangladesh, and Burma

Major geotectonic elements that are seismically active in the bear-shore areas of the Indian subcontinent are the Mekran fault off the coast of Pakistan, the western part of the Narmada-Son lineament, the West Coast Fault off the west coast of India - a southward extension of the Cambay Rift, the Palghat Gap, the Godavari and Mahanadi grabens, transecting rather at an angle to the eastern coast of India and the Arakan-Yoma arcuate belt of Burma, which is a part of the global Alpine-Himalayan orogenic belt, continuing southwards into the Andaman-Nicobar island complex and the Java-Sumatra trench on the ocean floor of the advancing Indo-Australian Plate. Observations along the coastal areas during historic and recent times, however, confirm the absence of significant tsunamis, though very mild tsunami surges have occasionally been observed along the coastal areas of the Bay of Bengal. No active volcanoes are known to exist in the coastal areas. Water reservois situiated near the marginal areas of the Peninsular Shield exhibit moderate to intense seismic activities, viz. Ukai, Bhasta, Koyna, Parambikulam, Sholayar, Idduki, and Kinnersani.(AU)

Earthquake countermeasures for the coastal protection dikes of lake Maracaibo, Venezuela : An update

The paper will review the activities carried out by the Venezuelan oil industry to reduce to acceptable levels the vulnerability of the coastal protection system to earthquake induced liquefaction.(AU)