Influence factors to flood disaster and search and rescue capacity in Thua Thien Hue delta

VNU Journal of Science, E arth Sciences 28 (2012) 153-159 Influence factors to flood disaster and search and rescue capacity in Thua Thien Hue delta Pham Thanh A n ’’*, Dao Dinh Bac^, N hu Thi Xuan^ ^Search a n d R escu e T echnical S e n ic e C enter, S u rvey a n d A e r ia l M a p p in g C o rp o tio n -D e fe n c e M a p p in g A g e n c y /1 Tran Cung, T u L iem , H anoi, Vietnam ^ G eo gra p h y Faculty^ V N Ư U n iv e rsity o f Science, 334 N g u y en Trai, H an oi, Vietnam R eceived 05 July 2012; received m revised form Auiiust 2012 A b stract Thua Thien Hue delta is one o f the strongest areas affected by natural disasters, esp ecially disasters related to water disasters such as floods, landslides coast T o have a scientific basis for the proposed measures to prevent and respond to m itigate the dam age and assist in search&rescue in the event o f floods need to study the factors that affect stroke floods and search&rescue capacity T his paper has identified the natural and man-made factors affecting flood disasters and search&rescue activities when disasters occur flood on Thua Thien Hue delta In particular, major role as geographical location, the study area is located in the transition zone betw een the Northern clim ate and Southern clim ate, the place where the dispute between the different air pressure, with m orphological characteristics o f terrain, exừem e weather, resulting in Thua Thien Hue delta is often effected by various types o f natural disasters related to water disasters, esp ecially floods The result analysis o f the factors causing floods w ill be the scientific basis for early warning, prevention and response, efficient support for search&rescue activities to reduce the loss o f life and property when flood disasters occur in Thua Thien Hue delta Context Thua Thien Hue delta is one o f the strongest areas affected by natural disasters, especially Flooding is a natural hazard phenom enon, disasters related to w ater disasters such as the result o f the concenfration o f w ater large floods, am ounts and overflowing into low teưain area (X I/1999) making wide flooding, causing dam age not only alaưning III level, T hua Thien Hue has m ade to people and property that also a long-term plain im m ersed in water, desừ oyed several negative im pact on the environm ent such as residential areas, killing hundreds o f people, w ater pollution, disease damages estim ated trillion It is the direct physical dam age, and the dam age to the landslides w ith coast flood In peaks flood history exceeded ecological environm ent can not fully assess * Corresponding author Tel: 84-988528809 E-mail; thanhan74@gmail.com 153 the 154 F T A n et al / V N U Journal of Science, Earth Sciences 28 (2012) 153-159 To have a scientific basis for the proposed generate flood or flooding phenom enon in measures to prevent and respond to mitigate the general T he first sub-system reflects the state damage and assist in search& rescue activities in of the event o f floods need to study the factors that com bination affect sứoke flooding and the ability to search atm ospheric disturbance factors) and abnormal and rescue This is the research content o f this changes o f sea level for the coastal areas, such paper as w ater level, w ater is draw n and unusually atm ospheric p recipitation of factors (rain, m onsoon a with high tides T he second sub-system consists o f the factors reflecting the presen t state o f terrain The factors that affect flood hazard and the ability to search and rescue when disasters occur on Thua Thien Hue delta The cause o f the flood disaster is derived from two basic factors, natural factors and manmade factors These factors are affected both directly and indirectly to the flooding Common factors independent nature, but in m any cases a combination o f both nature and man-made N atural fa cto rs: of endogenous buffer on tw o m ain aspects, w hich is the condition o f w ater to cause flooding or high flood level, or even generate flash floods, flood debris T his is determ ined prim arily by the topography type is clearly on the digital elevation m odel (D EM ): the presence o f the surface form sm all absolute height, the low range relative to around, etc, the second characteristic o f th e te a in buffer is the perm eability or w ater im pedir is defined by the and characteristics o f the vegetation, the physical exogenous origin Endogenous factors has a very im portant properties o f the m antle and crust o f the soil, the surface layer o f the lithosphere, the role, it indirectly affect flood on the earth's characteristics o f the p aren t rock, etc Both surface Endogenous factors, tectonic activity aspects o f the te a in b u ffer are reflected in the and new tectonic new characteristics in the process of of the source, or and hydrological geom orphological characteristics o f the terrain network and the formation o f the delta is a very o f the area So, co u ld be attributed to the important role Endogenous process usually analysis o f the interaction o f natural factors on takes very long geological cycles at a slower fertility and flood inundation o f the analysis rate but there is a very decided, create the consists o f three com ponents: geological foundation o f a large basin atm osphere - the physical te a in characteristics formation o f the surface Exogenous factors include landscape factors and the local landscape They have both direct and indirect im pact to flood through the role o f vegetation and nature o f seasonal hydrological regime o f rivers and oceanographic regim es rain - flood the continent, waves, tides, ocean circulation, sea-level rise state o f the - arising terrain (geom oiphological) In this interaction, if the p ro cess o f w ater volum e win, will generate flooding in varying levels, depending on the w ater volum e on the low terrain; conừ ary, w hen the process o f water drainage w in, extrem e w ater levels will not appear B y that logic, for T hua T hien Hue delta, we can see the sensitivity flooding as follows: Natural factors interact w ith each other in the system consists o f tw o m ajor sub-systems to - T he area is flooded ju s t norm al due to the rainy season, th e m o st sensitive; 155 P.T A n et al / V N U journal of Science, Earth Sciences 28 (2012) 153-159 - The situations area flooded single by season, rain in second storm kind of - The area flooded seasons by rain com bined in w ith storm tropical - T he area is flooded by rain in hurricanes situations convergence com bined circulation w ith and NE various changes it has gone through), so the study o f the geom orphology fraces and weather patterns causing floods will contribute to clarify convergence circulation, third-sensitive type; husband floods (flood left their m ark on the terrain, and then record the im pact o f the flo o d through sensitivity; situations dialectical relationship betw een they are for fropical the scale, causes and potential flood damage 2.1 Natural fa cto rs monsoon G eographical circulation, the fourth category sensitive; Easy to understand the depth o f flooding, duration o f flooding an d the level o f cause hazard also increased in the o rder m entioned situ ated in the climatic transition zone between Northern and Southern climate that ranges Bach M a is the natural climatic boundary between the two regions, and is located in the boundaries o f the above [1] typical tropical M a n -m a d e fa c to r s : a very im portant decision factor to regulate the natural flow from upstream is the rapid fluctuations o f w atershed vegetation due to deforestation, m ining and econom ic purposes obtain land for fanning, cattle breeding T he rap id decline o f vegetation, especially in the current w atershed protection forests have lost the ability to slow dow n the flood, the flow o f surface w ater, and this is actually one o f the m ain causes o f the the flood disaster In addition, the construction o f many works to regulate w ater reservoirs, dam s, dams regulate water, recounts line, w hether they shore location: spillway, salty dam , dredging has changed the natural hydrological regim e o f the river, and the traffic system , housing also im pede drainage causing flooding O n the other hand, planning in the d istribution o f population, the civil, social and econom ic decision likely hurt their different and dom inant of direction therefore search also the and rescue activities limited the 16 degrees latitude, the place where the dispute between the air flow com es from the different air pressure center: from the N orth came down, from the W est pass, from the encroaching on the East and from the South move up, usually the com bination of extreme weather phenom ena, and so located downsfream o f low and m edium m ountain ridges get wind, rain welcom e in W estern Thua Thien Hue, a center o f heavy rain m ost o f Vietnam; boundary between typical should usually ứopical have equatorial m any region strong w eather disturbances; located in the middle part o f the shoreline segments from Thanh Hoa to the exứem e South central perpendicular to the dom inant wind direction N orthEast coast often blocked by the estuarine sand trip and the sand bar extends parallel to the shore These characteristics o f the geographical location is one o f the main causes for here regularly suffered the ravages o f stonns and flooding As a result, there are often m any types o f natural D ue to the to pography and geom orphology o f T hua Thien H ue delta has areas w ith disasters related to w ater disasters, especially characteristics floods This set for the search and rescue than even the nearby coastal delta o f the central activities with specific objectives is to focus coast (as the T h u B on R iv er D elta) and the P.T A n et al / V N U Ịournal of Science, Earth Sciences 28 (2012) 153-159 156 energy and material resources to respond mainly to the flood disaster in the region Topography: if Southw est m ountains with characteristics o f rain, storm s and temperature, the characteristics of the atmospheric circulation and its interaction w ith the teưain very steep teưain beneath the coastal delta is did appear in this area disaster situations both low and not slope That makes conditions dangerous as flood floods, riv er bank erosion, for the flood took place so quickly in the study coastal [3] H ydrographic network: in general, due to area A teưain quite com m on in Thua Thien Hue rain seasons, the rivers are short and steep, delta IS in the N ortheast o f the dunes running v e g e ta tio n c o v e r w a s b a d ly d a m a g e d , so the parallel to the coast with a height o f 5-30m, the extreme fluctuations in a flow; the rainy season two asymmetric ribs, ribs fairly large W estern they are rivers full o f w ater, the w ater can slope 25"’-30°, the Eastern slopes laid over lO'’- repeatedly 15° These dunes make this delta having low disaster, while in the dry season, the v a lle y trip after dune, estuarine is narrow , difficult to floor are usually shallow , revealing the vast escape the water and the sand pressed into the golden sand, his m asterpiece receiver narrow, estuary shore, forced to flow in the stream leads by rainfall concenừated on the narrow and not slope, parallel to the coast, so that rapid steep, so the rivers are large flood peak flow is flooding when there is heavy rain, w ater from usually very high B esides the ancient river the W est down system, there is no recom m ended flood, so the Geology: the structure has decided to form the topography o f the delta by the parallel orientation o f the bar, the val-shore and estuarine sand trip extends in N W -SE direction, the same direction as the sand bar and m odem shore It is also a very notable feature o f the Thua Thien Hue delta, because they m ake a the interaction between the South Truong Son m ountain did appear a special variable type the rain is hea \7 rain during the autumn and w inter and less rain in the spring-summer period, range pearling in the W est form a wall o f rain took alm ost the entire amount due to w eather disturbances caused when winds from the east or in the w inter blow s from the Northeast The weather is rainy situation even m ore powerful combination o f interference w ith operation o f the tropical convergence m ajo r floods bring from steep m ountains to the low er thus accrue delta will very quickly, because there is flow not directly into the sea w hich w as congestion in the lagoon due to the floating sand dikes high flood events here can happen very quickly Oceanographic regim e: sea salt contribute monsoon circulation and the topography o f monsoon causing flood waters, they reactivate and foHTi the large flow o f flood A long w ith the rapid transition "grabens" valley and closed [2] Climate: hit zone, and main to speed up the process o f the t>pical brackish coastal lagoon on the Tam G iang-C au Hai, affect the structure o f ửie existing species, prom ote agricultural im plem ent m ore thorough and salinity solutions, especially solutions works and therefore also affect the ability to flood the region's natural m ig rato iy species groups Rising sea levels also change the process variable teư ain coastal and wetland expansion on the Tam G iang-C au Hai lagoon and the coastal plain, increasing the im pact o f floods on Thua Thien H ue delta and the Huong river Basin [3] 157 P.T A n et al / V N U Journal of Science, Earth Sciences 28 (20Ì2) Ĩ53-159 Soil characteristics: barren hills mainly in developm ent and im provem ent activities have the m ountainous areas w ith steep slopes, the calculated the risk o f com plications, the level o f source o f the river, so the rainy season increases risk is down, even if developm ent does not take the risk o f disaster phenom ena such as floods, into account the influence o f the level o f flood flash floods and m ud rocks, erosion, landslides risk due to accidents, the result is incalculable occur very serious Exploitation and im provem ent o f the natural Vegetation cover a n d lakes: Forest area accounts for a large proportion o f natural land, but over the years the forest has been devastated, the coverage decreased significantly, from the ability to regulate flood basin fell, poor w ater holding capacity, com bined w ith slope increase flood flow coefficient T he lagoon area lakes in the province accounts for nearly 5% o f the territory, but m ainly near the sea so little to regulate teưain for social life so growing human factor in increasing flood caused Due to pressure o f increasing coastal population and, o f course, is the economic developm ent needs requires more area under cultivation and housing, has exploitation o f the teưitory led to the o f a lack o f management, serious encroachm ent coastal flood corridor The uneven distribution o f with population concentrated mainly in the plain, on the both sides o f the river downsfream Along with characteristics o f the central region, may have econom ic activities such as sightseeing tourism, noticed, we determ ine the structure o f these industry, agriculture, aquaculture fishing have four countries, the direction o f flow, the process very sừong im provem ent o f virgin teưain o f accretion and erosion direct reflection o f the Residential areas located along the high ridge operation o f the flood, inundation Research and evaluate the role o f geom orphology o f the along the river espécially Hue City including many unique ancient architecture is built on delta and Its inherent characteristics related to alluvial o f H uong river along with high walls floods, really very useful and effective for the and proposed solutions to cope later A pplying the overflow s the banks will cause huge damage G eom orphological geom orphologic achievem ents analysis, characteristics: characteristics o f G IS calculation will of help, spatial with assist data drainage systems naư ow , the water in Despite dense irrigation network, including and rivers, canals dug in Huong Thuy, Phu Vang associated rem ote sensing data, digital elevation district, but by digging a long time, should not m odels, especially w hen com bined w ith expert be dredged regularly now heavily sediment, know ledge and making flood drainage capacity greatly reduced flood characteristics can m ake more accurate No large-scale reservoirs, with a capacity o f judgm ents flood sensitive areas, the relationship about 55 m illion - this reflects that zoning areas at risk, build high Existing irrigation in the plain key role to scripts prevention and search and rescue plan in provide irrigation water, rather than drainage case o f flooding [2] Therefore, analysis in geom orphology in o f flood control level is not some places this apparent draw back system like the roads to slow the 2.2 The m an-m ade fa c to r drainage flood plain w hen surface runoff It is an im portant factor in prom oting or Roads often have higher than the natural reducing the risk o f flood disasters If the terrain o f about 0.5m to 2m and main traffic 158 P.T A n et a i Ị V N U ]ournal o f Science, Earth Sciences 28 (2012) 153-159 routes also play an im portant role in the process air m asses) T h at is the reason for the Thua causing floods 1A N ational Road w ith a height T hien H ue delta annual rainfall depending on o f 1.5-2m runs parallel to the sea, n aư o w the type o f the h ig h est in the counữy, but drainage aperture formed dam s prevent flood unevenly large parts o f the w estern plains units flooding m onths, so flooding w as b o m very intense The in rainy season this is clear in the historic floods o f 1999: in many roads, flood who breached distribution o f rainfall in space and time flood them to make escape routes flood erosion changes in the nature and in each section o f the principle backwards for geophysics online form river and its tributaries F lood flow w ith great located perpendicular to the direction o f spread speed, w hile the plain is a narrow , iow-lying transmission o f the flood areas, close to the foothills o f the m ountain, it is In addition to the above factors affecting areas dow nsừeam is influenced by tides, stoưn distributed, m ainly in the rainy are very com plex, creating floods have massive blocked from th e sea by a typical lagoon system , the focusing speed IS very rapidly from surges When flood to m eet surges, or surges will reduce downsfream flood water surface a netw ork o f short rivers and sưeam s, the slope, the ability to drain the sea slowed down, foothills to the W est In this context, the flow leading to rising flood w ater levels than norm al rate is usually very large, w hen rolled dow n’ve At low tide, the w ater surface slope as well as created large and rap id ly rising w ater, causing the flood flow rate increases, the m om ent the serious flooding average slope derived from the m ountains and amount o f flood w ater to drain faster, and the We can not com pletely allelopathic destructive pow er o f ửìe flood flow is also m ore natural disasters in general and flood disasters dangerous - large flow rate will be w ashed in the region in particular, but can be active in away many houses, projects, river bank erosion, the w ork o f early w arn in g (ie w arns practical etc All o f these features need to be included in areas will be flooded w ith tim e and depth o f the flood and disaster prevention plans, rescue flooding scenario locally location and the w eath er is rainy different flood), vary according prevention and to geographical response, efficient support for search and rescue w ork to reduce Conclusion low m ost dam age to people and the flood disaster occm red Research area, Thua Thien Hue delta is always potential risk o f flooding due to the natural geographical conditions w ith specific References characteristics o f ửie region, especially the morphological characteristics o f the topography associated with the arising in the process (ie the form directly and objectively reflect the operation o f flood and w aterlogging) The w eather that caused flooding, storm, ữopical depression, tropical convergence zone (single operation or in com bination with cold [1] Pham Thanh An, D ao Dinh Bac, Nhu Thi Xuan (2011), Integrated remote sensing and GIS technologies in support o f disaster search and rescue activities in Vietnam, Journal o f G eodesy an d C artograph y (Journal o f Geodesy and Cartography, ISN: 0866-7705), Institute Science o f G eodesy and Cartography, Ministry o f Natural resources and Environment, No 9, September / 2011, page 54-58 P.T A n et a i / V N U Journal o f Science, Earth Sciences 28 (2012) 153-159 [2] Nguyen Hieu, Dang Van Bao (1999), The study o f landform ch a cter tics affect sensitivity f lo o d Hue delta on the b a sis o f rem ote sensing and GỈS applications, the report projects at the University o f Science, 35 pages [3] Nguyen Thi Viet Lien (2011), Risk Assessm ent o f coastal Thua Thien - Hue due to sea level 159 rise and build decision-support software Independent project report Cooperation between Institute o f Science and Technology o f Vietnam and the People's Committee o f Thua Thien Hue 2009-2010, Institute o f Mechanics  ... when disasters occur on Thua Thien Hue delta The cause o f the flood disaster is derived from two basic factors, natural factors and manmade factors These factors are affected both directly and indirectly... assist in search& rescue activities in of the event o f floods need to study the factors that com bination affect sứoke flooding and the ability to search atm ospheric disturbance factors) and abnormal... f the flood areas, close to the foothills o f the m ountain, it is In addition to the above factors affecting areas dow nsừeam is influenced by tides, stoưn distributed, m ainly in the rainy are