1. Tropical Storm Allison & its impact on Harris County
Binbin Chen

2. Introduction
Tropical Storm Allison formed 80 miles off the coast of Galveston, Texas on June 5, 2001
Over the next 5 days, Allison produced record-setting rainfall, flooding and damage in Harris County and city of Houston
Because of the magnitude of flooding, Harris County Flood Control District and FEMA specially performed a project “Tropical Storm Allison Recovery Project (TSARP)”

3. Flooding after Allison
22 fatalities
95,000 damaged automobiles
73,000 damaged residences
Over $5 billion in property damage

4. Project Purpose
Perform an evaluation of the storm and its consequences in Harris County
Storm Track
Precipitation
Stream discharge
Flooding area
Better understand water resource data and how to integrate different source data using ArcGIS

5. Data Sources
National Hurricane Center provides historical tropical ecyclone track GIS data at:
National Climate Data Center provides NEXRAD Radar rainfall data at:
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

6. Storm History &Track
wind speeds (in KTS, 1Windmph=1.15WindKTS)

7. Storm Precipitation Rain gages
-150 rain gages operated by Harris County Office of Emergency Management (HCOEM)
-3 rain gages operated by National Weather Services (NWS)
Radar data
-NWS collected rainfall radar data at WSR-88D radar site covering the Houston area

8. Obtaining rainfall data
Visualize data in NEXRAD Viewer
Visualize data in NEXRAD Viewer
Downloaded raw radar data
Download raw radar data
Export radar data into ESRI raster data using NEXRAD exporter
Export radar data into ESRI raster data using NEXRAD exporter

9. Storm Total Rainfall
*One Rain gage at Greens Bayou recorded the highest rain as 38 inches.

10. Total Rainfall from June 5 to June 7

12. 14-hour Rainfall

13. Source: TSARP report

14. Stream discharge

21. Source: TSARP report

22. Flooding Area

24. Flooding land in Houston

25. Flooded Major Roads

26. Conclusion
Tropical Storm Allison was the most damaging tropical storm in Harris County.
Harris County received the heaviest rainfall from 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 19,2001
A large amount of lands & roads in Harris County were flooded.
ArcGIS has the powerful function to integrate different source data, visualize and analyze data, and depict a clear picture of the storm event, which helps people understand flooding and flood risk and better prepare for the next “Allison”.

27. Questions?