Comparison between 1D and 2D models to analyze the dam break

Ignacio Valcárcel LencinaTRITA LWR Masters Thesisnetwork and power supply etc. makes the situationespecially difficult for rescue operations. Thus thepopulation in the danger area must be evacuatedbefore the arrival of a flood wave.The essential part of warning the population is to getthe population to take the action necessary. Peoplemust be convinced of the reality of the danger andthey must be advised to act according to theinstructions of rescue authorities. A mere warning isoften not enough. People in danger need instructionson how to save themselves from a threateningsituation.Definitely the most important factor affecting thewarning, evacuation and rescuing of the localpopulation is the time period between dam failure andnotification of the failure and commencement of therescue operation. If a dam failure alarm is given late,the conditions for making emergency repairs to thedam are poor and the probability of human casualtiesincreases.At the same time the benefit from the public alarmsystem installed to the dam danger area is lost. Thenotification speed of the dam failure has beenobserved to have a direct correlation to the loss ofhuman life (Douglas et al. 1999, Lemperiere 1999). Thesafety monitoring of the dam must correspond to therisk factors of the dam. The greater the failure risk ofthe dam, the greater the demands on dam safetymonitoring functions.The credibility of following warning methods andachieving the necessary action was assessed:• public warning signals (sirens)• emergency bulletin on the radio• loudspeaker vehicles of rescue units• telephone and mobile phone (group calls)• warning people indoors from house tohouse.Public warning signals are best suited to urban areas,because an alarm can be given quickly and a largepopulation can be reached. The working state ofequipment is generally secured using backup batteries,to make sure the system is independent from anexternal power supply. Spoken messages andinstructions can also be given using modern electronicequipment.One problem with public warning signals is thecredibility factor – do people believe that the danger isreal. In addition to a public alarm signal, attentionmust be paid to the visibility of the warning.The success of a warning operation is partlydependent on the fact that the population is aware ofliving in a dam danger area. If a lot of people, whosesafety the rescue services cannot guarantee in case ofan emergency, are living in a dam danger area, anindependent initiative is also required for escaping thedanger area. The population must be aware of thepossible personal danger so that they can protectthemselves and act on their own in case of anemergency. The necessary information can bedistributed through an advance information bulletin.This bulletin has a special purpose due to the nature ofa dam failure. In case of a chemical or radiationemergency, the population may be able to protectthemselves in their homes, but in case of a dam failurethe situation is different. Some buildings fill with waterand collapse due to structural strain of masses ofwater, whereas some buildings remain intact. Thebulletin is very important for the credibility of thewarnings and decisions about action taken in a damfailure situation. The bulletin decreases the need for anindividual to find further assurance of the threateningdanger and gives a prepared operational model forescaping the danger area.The purpose of warning and evacuation is to evacuateareas that will be flooded according to the inundationmaps. This applies in particular to buildings withoutupper storeys. Rooms below ground must always beevacuated.Rescue authorities carry out evacuation in dangerareas. Taxis, local buses and ambulances are used asevacuation vehicles in the evacuation organised by therescue authorities. If people living in the danger arealeave on their own, they go on foot, use their ownvehicles or other means of transportation. Whenwarning and evacuating people, they are instructed totake personal medication with them.Vehicles used for evacuation are alerted to specifiedmeeting places by the emergency response centre.There drivers are given their tasks as well asinstructions and materials required to execute thetasks. Subsequently vehicles are sent to the evacuationareas to execute their evacuation tasks. Evacuationunits execute the evacuation under the supervision ofthe personnel of rescue services. Vehicles are not toproceed with the evacuation on their own, sincedrivers may have problems managing anxious peopleon their own.Evacuated people are taken to evacuation centres.These centres are organised by the social and healthservices using voluntary rescue service personnel. Thelocation of the evacuation centre must be planned sothat a dam failure does not have an effect on its waterand heat supply, distribution of electricity and sewagesystem.The following supply services are organised in theevacuation centres:• first aid• crisis bulletin for evacuated people, theirfamilies and people who have lost theirhomes• psychosocial help for evacuated populationand people who have lost family members orfriends• catering and clothing for evacuatedpopulation28