Stream flow data useful as long as water remains in the stream bed. During an extreme flood, water will spill over dikes. Note caution in using these numbers.
Planning for Climate Resilience: learning from typhoon Mirinae
Michael DiGregorio PhDPlanning for Climate Resilience:learning from typhoon Mirinae
Typhoon Mirinae: 30 Oct-2 Nov 2009• On the morning of 2 November 2009, tropical storm Mirinae, with wind speedsof 109 kph, makes landfall in Phu Yen province. It is the 11th tropical storm to hitVietnam that year.• Deputy Prime Minister Hoang TrungHai issues disaster preparation instructionson 30 October. In BinhDinh, schools are closed on 2 November and people areadvised to prepare for the storm.•Phu Yen, the province hardest hit by Mirinae, reports that floods and strong windhas claimed at least 78 lives. In BinhDinh, 22 people are reported dead and 3reported missing. In KhanhHoa, further to the south, 14 deaths are reported.• Between 2-3 November, 801 mm of rain falls in Van Canh, BinhDinh.• In late October, Bùi Minh Tăng , director of the Central Storm ForecastingAgency, announces that the storm is powerful, rapid and will produce up to 400mm of rain in Central Vietnam.• Provincial governments report a total of $280 million in damage to property.
Rainfall by hour, Van Canh&QuyNhon2-3/11/ 20094-5 pm 8-9 pm 12-1 am
Sông Hà ThanhĐầm Thị NạiTỉnh Phú YênP. Nhơn PhúTT Vân CanhTT TP Quy NhơnTT Diêu Trì4-5 PM8-10 PMP. Nhơn Bình7-9 PM 6-7 PM10 PM-4 AMTyphoon Mirinae: Evolution of a FloodFlood chronology by area. Time flood first noticed in yards. Based on interviews.
Ward orCommuneDamage AssessmentCoastalfisheries, boatsand tackle$373,495 including $305,470 in damage in DongDa and $68,025 in Nhon Binh. Damage to fishponds accounted for 88 percent of the total.Industrialzones$10,432,171 in damage to industrial zones inNhon Binh ($9,937,853), Bui Thi Xuan($440,121) and Phuoc My ($36,392).Housing$1,343,430 in total damage to homes. 2,061 ofthe 2,302 homes damaged or destroyed duringthe flood were in Nhon Phu.Dikes, roadsand irrigationsystems$1,445,888. The largest losses were in NhonPhu ($481,944) and Phuoc My ($472,370).Together, Nhon Phu and Phuoc My accountedfor 67 percent of all damages to dikes, roads andirrigation systems.Agricultureand livestock$3,183,528. In Nhon Phu and Nhon Binh, lossof livestock and loss of rice in storage accountedfor a majority of the $1,760,820 in damage. InPhuoc My, loss of livestock and damage to fruittrees accounted for a majority of the $647,388 indamage.Forestry$2,708,023. 98 percent of the total damageoccurred in Phuoc My, where 19 sq. km. ofindustrial forest was damaged or destroyed.Đống ĐaNhơn BìnhNhơn PhúBùi Thị XuânPhước Mỹ
Historical Flood Pattern:With Few Barriers in the Flood Plain, Water Drained QuicklybridgesVan Ha RR Hwy19Hung VuongThi Nai Lagoonagricultural villages agricultural villages fisheries villageslow roads lowembankmentSeasonal floods generallyrose and fell graduallyover a 8-12 hour period,often at night.During severe andextreme floods, watercould easily and quicklypass over the top of lowroads.Because settlements in thefloodplain were few andconcentrated, floodwatercould spread out over alarge area.Slope of 8 meters in 8kilometers from Van Ha toThi Nai allowed water todrain quickly
Nhon PhuDong DaDieu TriNhon PhuWeirWeirKon riverTuy PhuocNhon BinhHwy 19Hung Vuong St.Northern DikeEastern Dike⏏⏏⏏⏏⏏⏏⏏ ⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏Typhoon Mirinae:Impacts of Infrastructure and Urbanization on Floodingbridgeriver river RR Hwy 19 & Hung Vuong dike lagoonagricultural villages agricultural villages fisheriesvillagesbridgedikebarrageCCN KTDCĐHQTlow roads2.0m 2.0m 2.0m 2.0mThi Nai BridgebridgedikeFlooding in the lower HaThanh River occurs whenwhen the flow of water inthe riverbed is greater than1,226 m3/second.During the 2009 flood,river flow reached 3,328m3/second.Barriers in floodways andinsufficiant drainagecapacity raised the level offlooding.+11 cm+03 cm+70 cm+07 cm⏏ BridgeRailroadUpgraded Dike SectionOld Dike SectionMain RoadLEGEND+13 cm+40 cmIMPROVING DRAINAGE IS KEY TO REDUCING FLOOD RISKS
⏏ BridgeRailroadUpgraded Dike SectionOld Dike SectionMain RoadLEGEND⏏⏏⏏⏏⏏⏏⏏ ⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏Dong DaDieu TriNhon PhuNhon BinhArea Plan for Nhon Binh: Impacts on FloodingNhon PhuIf the current area plan isbuilt as planned, a floodsimilar to Mirinae wouldproduce deeper flooding.⏏+33 cm+50 cm+70 cm+76 cmThe Area Plan for NhonBinh proposes filling inroughly one third of theward’s area.It also reduces the floodchannel to a narrow areabetween Bridge No. 7 and8, and Barrage No. 2.
⏏ BridgeRailroadUpgraded Dike SectionOld Dike SectionMain RoadLEGEND⏏⏏⏏⏏⏏⏏⏏ ⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏Dong DaDieu TriNhon PhuNhon BinhArea plan for Nhon Binh:Impacts on Flooding under Climate Change and Sea Level RiseNhon Phu⏏Based on our hydrologicalmodel, by 2050, underconditions of ClimateChange and a Sea LevelRise of 26 cm, a stormsimilar to Mirinae, whichproduced floods greaterthan 2m in depth in mostareas of Nhon Binh andNhon Phu, would producemuch deeper flooding.+41 cm+77 cm+90 cm+89 cm
Hydrological impacts of urbanizationNhon PhuDong DaDieu TriNhon PhuTuy PhuocNhon Binh⏏ BridgeRailroadDike/Dike RoadMain RoadLEGEND⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏⏏If all the plans for QuyNhon are implemented,floodways would beseverely narrowed,creating the potentialfor overtopping innewly urbanized areas,worsening flooding inlow areas of Dieu Triand Tuy Phuoc.increasing risks forpeople living infloodways, andTuy Phuoc
• Manage upstream threats• Improve flood warning and the training of community leaders• Restore and improve drainage in the Ha Thanh River floodplain.• Limit new residential, industrial and infrastructure development in thefloodplain of the Ha Thanh River.Recommended actions