Flood warning systems

The nonstructural or preventative measures that could be adopted include floodplain regulations such as zoning laws that stipulate where development may or may not occur, building codes that put restrictions on basements and the permissible amount of impervious cover allowed on the site, open-space requirements for large-scale developments, and designing flood warning systems to provide advance notice about impending problems. 

An obvious major shortcoming of Thailand s disaster management system was the absence of an accurate tsunami early warning system monitoring the Indian Ocean. (Bird and Lubkowski, 2005) A Pacific Tsunami Warning System did exist, of which Thailand was and is a member state. Although Thai officials were duly notified by the warning system s staff that an earthquake had occurred, this information was not transmitted adequately to local authorities - for fear that it would harm tourism As a consequence, an evacuation alarm was not sounded, and the tsunami floods entered surprised and unprepared communities. Loss of livelihood may have been unavoidable even if the information had been transmitted optimally, but the death toll would have certainly been lower. (Wilcox and Horwitz 2005 UNEP 2005 Weisman, 2005). 

There is no evidence of the existence of both a flood Early Warning System (EWS) and an Early Warning Coordination Centre (EWCC) at the level of the State of Tabasco (i.e. at recursion 1 or level 1 see Figures 9 10). 

The data obtained from flood forecasting and monitoring systems and from the operation of any warning systems should be periodically analysed for changes in the flood characteristics of drainage basins, including... 

The warning system should be used in connection with forecasting models since the time period that would be necessary for operator actions to put the plant into a safe status may necessitate acting on the basis of extrapolations of the trends in phenomena without waiting for the actual occurrence of flooding. 

A warning system is available that is able to detect a potential flooding of the site in sufficient time to complete the safe shutdown of the plant, together with the implementation of adequate emergency procedures ... 

The flash floods hydrometeorology is complex and in Liguria it is complicated by tyrrhenian catchment fragmentation. Uncertainty, even given meteorological RADAR near-time forecast, is large than the timeline of early warning systems. 

Real-Time Expert System (RTXPS) is a system designed for on-site dynamic emergency management in the case of technological and environmental hazards, including early warning for events such as toxic or oil spills, floods, and tsunamis. 

Obviously this needs careful consideration. Urqrredictable behaviour in emergency situations is imdesirable. As an example, some years ago a computer installation was plarmed with CO2 gas flooding for fire control. Exit times after warning before the flood activated were calculated. However, this did not allow for an employee in a wheelchair. As mentioned earlier, a new flooding gas called Inergen allows breathing for a limited time. A water micromist system is another solution, even in computer facihties. 

Grijsen, J.G., X.C. Snoeker and C.J.M. Vermeulen, 1992. An information system for flood early warning. 3rd international conference on floods and flood management, Florence, Italy, Delft Hydraulics Publication. 

Moreover, a special evaluation should be carried out so as to avoid potential small deviations in plant parameters from giving rise to severely abnormal plant behaviour ( cliff edge effects ) in relation to the specific nature of the external event scenario (e.g. in the case of a site protection dam, if as soon as the dam is overtopped vdth a small additional steady state water level, the site could be suddenly flooded to the maximum level of the flood). In this case, addi-tional engineering provisions should be implemented on safety systems at least for a safe shutdown mode, such as warning, monitoring and operating procedures. 

Figure 9.66 Typical warning sign to a computer room fitted with a flood system...

An important feature of any flooding system must be the method by which the system is prevented from being operated while the space is occupied. In all cases the extinguishing media will harm and may kill the occupants of any confined space in which it operates. Systems are often designed to be operated when the space they protect is unoccupied. Other systems provide pre-warning to occupants or rely on manual operation. 

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