Atlas 14 Study Shows Changes for the Austin Area

Atlas 14 Study Shows Changes for the Austin Area

Atlas 14, a study of historical rainfall data and events performed by the National Oceanic and Atmospheric Administration (NOAA) and was released in late 2018. The study shows that Austin is one of the more significantly impacted locations in Texas – so, what could that mean for Austinites?

  • City codes may be updated
  • Floodplains will be expanded
  • Developments, remodeling, or redevelopments may be affected
  • The need for and the cost of flood insurance may change depending on FEMA’s map updates that affect the City. This is due in large part because of the Atlas 14 Study and subsequent map revisions that will occur

How can a study about rainfall intensity be the impetus that causes varied and significant changes? Rainfall intensity data tells the likelihood of rainfall events of different sizes. The data is then used to determine flood risk and to create floodplain maps. Prior to the Atlas 14 study, Texas rainfall intensities had not been assessed since 1994. Atlas 14 incorporates all data gathered since 1994, up to and including Hurricane Harvey.

The updated data shows significant changes, including that more people and property are at risk of flooding than was previously realized and that there is an increased level of risk for areas that were already in the floodplain. One example of the changes is that what is considered a 500-year rainfall amount on the current data is statistically relatively close to the new 100-year rainfall amounts in around the City of Austin. Below is a table that reflects some of the changes that Austin will see.

 

The City of Austin released a Summary of Recommended Code Changes after the final draft of the Atlas 14 study was released. Within the recommended changes, the City proposes:

  • Amending the definitions of the 25-year and 100-year floodplains to add more clarification
  • Creating exceptions for buildings in the 25-year and 100-year floodplains
  • Updating several technical codes

Public meetings were held in September and October of 2018 and stakeholder meetings are ongoing. The Zoning and Platting Commission, Environmental Commission, Planning Commission, and the Austin City Council will conduct public hearings beginning in January 2019. Following all public hearings, the Austin City Council will consider adopting the proposed amendments to the regulations.

As cities, counties, and other municipalities make decisions regarding actions to take due to the Atlas 14 Study, Jones|Carter will provide updates on the blog to help keep our followers up to date regarding what is happening in their own back yard. If you would like to receive blog updates, please subscribe to our monthly post summary. If you have any questions about Atlas 14, Speak to an Engineer or follow us on LinkedIn.

Helpful Links:

https://www.jonescarter.com/blog/featured/atlas-14-what-is-it-and-how-could-it-affect-you-or-your-project

To look at the flood risk in the Austin area, go to www.hATXfloodpro.com, click on “I want to…”, then click “Explore Atlas 14 Changes.”

http://www.austintexas.gov/sites/default/files/files/Watershed/flood/atlas14_presentation_9_12_18.pdf

http://austintexas.gov/atlas14

http://austintexas.gov/page/atlas-14-and-austin

http://www.austintexas.gov/sites/default/files/files/Watershed/flood/atlas14_reference-sheet_FINAL.pdf

http://www.austintexas.gov/page/flood-risk-and-atlas-14-details

https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html?bkmrk=tx