William Terry, a water resources section chief with the Corps, outlined how a detailed analysis of the floodplains in Wilson County could at least help prepare for significant rain events.
" Wilson County is going through tremendous growth right now, so your hydrologic conditions are actively changing," Terry said. "As you continue to have development, you have more impervious areas, which means more runoff ends up in streams."
The ever-changing nature of those flood conditions make predicting and preventing flooding damage difficult. Terry said that the best way to combat that is to have as updated floodplain data as possible.
Much of the data compiled on Wilson County floodplains is outdated, with nearly half of it being more than 30 years old. Terry mentioned that technology has come a long way, lending itself to more advanced and accurate floodplain data.
"Much of the old data was compiled from topographical maps," Terry said.
A lot of the data points to increased intensity and higher frequencies of water-significant events in Wilson County.
Terry reported that since the 1950s, three of the four most significant rainfall events in Wilson County have occurred within the last 12 years.
"It's not necessarily more rainfall (on average) ... it's just more intense events," Terry said.
He used the floods from Waverly last August as an example of intense rain events.
"No structure can be implemented to reduce the impact of 20 inches of rainfall," Terry said. "The best way a community can be prepared is to know where it might flood."
The ACOE does assist local government entities in the types of studies discussed on Tuesday.
Terry indicated that the county's contribution for a study that would yield two or three fully-mapped watersheds would be approximately $100,000 to $150,000 per year. Any move like that would require a letter of intent from county officials indicating a desire to move forward with the grant. A few of the officials at the meeting suggested that such a letter would be discussed in greater detail among the appropriate committees.
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