Tropical Storm Allison Tropical Storm Allison & &
its impact on Harris Countyits impact on Harris County
Binbin ChenBinbin Chen
IntroductionIntroduction
• Tropical Storm Allison formed 80 miles off the Tropical Storm Allison formed 80 miles off the coast of Galveston, Texas on June 5, 2001coast of Galveston, Texas on June 5, 2001
• Over the next 5 days, Allison produced record-Over the next 5 days, Allison produced record-setting rainfall, flooding and damage in Harris setting rainfall, flooding and damage in Harris County and city of HoustonCounty and city of Houston
• Because of the magnitude of flooding, Harris Because of the magnitude of flooding, Harris County Flood Control District and FEMA specially County Flood Control District and FEMA specially performed a project “Tropical Storm Allison performed a project “Tropical Storm Allison Recovery Project (TSARP)”Recovery Project (TSARP)”
Flooding after Flooding after AllisonAllison
22 22 fatalitiesfatalities
95,000 damaged 95,000 damaged automobilesautomobiles73,000 damaged 73,000 damaged residencesresidences
Over $5 billion in property Over $5 billion in property damagedamage
Project PurposeProject Purpose
Perform an evaluation of the storm and its Perform an evaluation of the storm and its consequences in Harris Countyconsequences in Harris County
• Storm TrackStorm Track
• PrecipitationPrecipitation
• Stream dischargeStream discharge
• Flooding areaFlooding area
Better understand water resource data and Better understand water resource data and how to integrate different source data using how to integrate different source data using ArcGISArcGIS
Data SourcesData Sources
• National Hurricane Center provides historical tropical tropical ecyclone track GIS data at: ecyclone track GIS data at: http://http://maps.csc.noaa.gov/hurricanes/viewer.htmlmaps.csc.noaa.gov/hurricanes/viewer.html
• National Climate Data Center provides NEXRAD Radar rainfall data at: http://lwf.ncdc.noaa.gov/oa/radar/radarresources.html
• NHD (Unit 1204) & NHDplus (Unit 12a) provide surface water data of Harris County
• USGS stream gages & real time data
• Harris County Flood Control District Provides Harris County watersheds data and flooding area data
• City of Houston provides city land use data
Storm Storm History History &Track&Track
Storm PrecipitationStorm Precipitation
• Rain gagesRain gages
-150 rain gages operated by -150 rain gages operated by Harris County Harris County Office of Emergency Management (HCOEM) Office of Emergency Management (HCOEM)
-3 rain gages operated by National Weather -3 rain gages operated by National Weather Services (NWS) Services (NWS)
• Radar dataRadar data
-NWS collected rainfall radar data at WSR--NWS collected rainfall radar data at WSR-88D radar site covering the Houston area88D radar site covering the Houston area
Downloaded raw radar Downloaded raw radar datadata
Visualize data in Visualize data in NEXRAD ViewerNEXRAD Viewer
Export radar data into Export radar data into ESRI raster data using ESRI raster data using NEXRAD exporterNEXRAD exporter
Obtaining rainfall Obtaining rainfall datadata
Download raw radar Download raw radar datadata
Visualize data in Visualize data in NEXRAD ViewerNEXRAD Viewer
Export radar data into Export radar data into ESRI raster data using ESRI raster data using NEXRAD exporterNEXRAD exporter
Storm Total Storm Total RainfallRainfall*One Rain gage at Greens Bayou *One Rain gage at Greens Bayou recorded the highest rain as 38 recorded the highest rain as 38 inches.inches.
Total Total RainfallRainfallfrom June 5 to June 7from June 5 to June 7
14-hour Rainfall14-hour Rainfall
Source: TSARP Source: TSARP reportreport
Stream Stream dischargedischarge
Source: TSARP reportSource: TSARP report
Flooding Flooding AreaArea
Flooding Flooding land land in Houstonin Houston
Flooded Major Flooded Major RoadsRoads
ConclusionConclusion
• Tropical Storm Allison was the most Tropical Storm Allison was the most damaging tropical storm in Harris County.damaging tropical storm in Harris County.
Harris County received the heaviest rainfall from Tropical Storm AllisonHarris County received the heaviest rainfall from Tropical Storm Allison Streams in Harris County were greatly affected by Tropical Storm Allison, Streams in Harris County were greatly affected by Tropical Storm Allison,
17 out of 44 stations reached record peak flow on June 19,200117 out of 44 stations reached record peak flow on June 19,2001 A large amount of lands & roads in Harris County were flooded.A large amount of lands & roads in Harris County were flooded.
• ArcGIS has the powerful function to ArcGIS has the powerful function to integrate different source data, visualize integrate different source data, visualize and analyze data, and depict a clear and analyze data, and depict a clear picture of the storm event, which helps picture of the storm event, which helps people understand flooding and flood risk people understand flooding and flood risk and better prepare for the next “Allison”.and better prepare for the next “Allison”.
QuestionQuestions?s?