Vulnerability of East Iran Railway against Floods (PAP015856)

Código

PAP015856

Autores

Manijeh Ghahroudi Tali

Tema

Urban Floods

Resumo

Railways ofIranespeciallyinarid has been damaged of flooding recently.Most ofthe flooddamageswere happened on the bridgesrailway. Themain reasoncan be found inthe context ofchanges in riverbed, suddenheavyrainfall,andcoarse sediment.Dasht-eLutand Dareh-Angir basins in theEast of Iran are flat and covered bySaltland that the railway network goes through the north of the area. Length of Railwayinthestudy areais220.13kmandareas of catchments are8641.27Square kilometers. There are a lot of watercourses. Due totheabundanceofcoarse sediment and flatness, the streamsarechanging their bed in this area. Thus,morebridgesareprone tofloodingand runoff.The goal of thisresearch is toassessthe railway vulnerability offlood. Datasourceswere used inthe research consistedoftwo parts: thefirst partof thedatais international Database and the second isthe data from1:25000topographicandelevationdataof Asterimages with pixelsizeof 30 m. They have been replaced to increasethespatialresolutionofthesedata.Also 23 samples were taken of sediment under bridges. Theinternationaldatabase consist GSMaP (JAXA) cover-area,digital elevation data, hydrology, landusefromGTOPO30 (USGS)withresolution30 seconds, land-use GLCC (USGS), Hydro (NASA) Spatial resolution ofpixel1 kmandGlobal Map (ISCGM) Spatial resolution30 seconds.Thisresearch was conductedintwostages,in the first stagea Surface Tank Model, of aset Distributed hydrological modeling, was usedinIntegrated Flood Analysis System (IFAS) software. The modelconsistsofa surfacereservoirtosurfaceprecipitation, the average flowvelocity andinfiltration flow. Thesecondphase Indian Council of Agriculture Research (I.C.A.R) modelhas been used toevaluate the results. The IFASresultsshowed that 70 percentofthe railway betweenRobatposhtbadam to Khonjstations, Jandagh to Chadormaloo and Chahmohammadu and also part ofRaml to Jandaghwhich thewholerailway220.13kilometersfacedtofloodingandrunoff.Theresultsobtained comparedwith Runoff from theICARmodelthat presented thatrunoffin ahigh risk areais amaximum heightrunoff. A totalheightof the runoff is more than 100 cm.Due to none uniform of rainfall and seasonal rainfall, annual runoff in the area are more.Results fromthe field researchina high risk areabetweenRobatposhtbadam and Talehamid to khonjstations, showedthe destructioncaused by thefloods. The result ofthechannelgranolometery was shown that themediangraindiameter (D50)isapproximately2 mm, which represents theintense floodinginthe area.Finallyt-Traskindicatorswere usedto identifyflooddepositsfrom other. This index haschanged from1.8to 2.7fordepositsfromfloods.Thisindicatorranges were between2.45 to 2 forthe 23samples. Thefindingssuggest thatsedimentaccumulationhas been movedunder thebridgebyfloodwaters.