Water and erosion can cause untold damage to Tennessee’s homes, properties, roads, and infrastructure.
Cornell ecology professor David Pimentel explained: “Erosion is one of those problems that nickel-and-dimes you to death.” During a rainstorm, if just one millimeter of soil washes away across a 2.5-acre parcel, a total of 13 tons of topsoil are lost.
The varied Tennessee landscape means that different areas of the state face different levels of erosion threat. Find out which Tennessee city has the worst erosion rates.
How Is Erosion Affecting Cities in Tennessee?
Erosion is the natural process where soil is carried away by natural forces like water movement or wind. Rates of water erosion will vary based on rainfall amounts, topography, waterways, soil type, and surface coverings. For example, a steep hill with no vegetative cover can have higher erosion rates than rolling hills that have plant protection, which can hold the soil with its roots.
To find out which Tennessee city faces the worst erosion problem, we used county-level erosion data from the USDA’s National Cooperative Soil Survey. The comparison below looks at Kw erosion, which is the K factor for whole soil, and its susceptibility to sheet and rill erosion by water.
The Memphis area has the highest rate of erosion in Tennessee. Nashville, Chattanooga, and Knoxville are in the middle of the pack, and Clarksville has the lowest erosion rate of the cities we analyzed.
|Erosion Rank||City||County||Erosion Index|
|6||Johnson City||Washington County||0.31|
Why is Erosion in Western Tennessee so Bad?
Erosion is affected by local conditions, and two main issues are driving high erosion rates in west Tennessee.
The first issue is that the soil in the region is highly susceptible to erosion. A retired professor from the University of Tennessee Institute of Agriculture describes the silty soils are “almost like talcum powder,” explaining the soil is “easily moved by water if [it’s] exposed and tilled.”
The other issue is flooding. Heavy rainfall and overflowing waterways can create widespread flooding events that cause significant water damage. As water overtakes cities and towns, it has the power to carry away soil as well as larger infrastructure like roads and heavy objects like cars. The Memphis branch of the National Weather Service says to “never underestimate the power of flowing water.”
How Do the Steep Grades of Chattanooga and Johnson City Affect Erosion?
In the eastern half of Tennessee in cities like Johnson City and Chattanooga, there’s a lower erosion rate than in western cities like Memphis. However, there are different water risks associated with the terrain.
In Chattanooga’s Hamilton County, there is a 4,347-foot elevation change between the county’s mountaintops and valleys. Washington County has an elevation change of 3,530 feet. These steep grades can cause other risks such as mudslides, landslides, and falling rocks.
Even though landslides and erosion are different geological processes, they are both related to water. Heavy rain, surface runoff, or saturated soils can prompt a landslide. The amount of soil and rock movement can be dramatic, as evidenced in this landslide in Polk County.
Erosion and landslides have been a hotly debated topic in Chattanooga, and the city has seen an increase in slope development in recent years. On steep slopes greater than 25 percent grade, there were fewer than 53 land disturbance permits issued annually between 2009 and 2014. However, between 2015 and 2018, the number of permits per year ranged from 121 to 315. When soil is disturbed on these steep slopes, storm water runoff can lead to significant erosion, which can damage downhill properties.
What Can You Do to Protect your Home from Erosion and Flooding?
Water management is key to protecting your home. As foundation repair experts, we’ve seen stormwater flow right into people’s yards and flood their basements. We’ve seen overflowing rivers tear away concrete. We’ve seen heavy rains flood homes, ruining belongings and causing extensive structural damage.
AFS helps homeowners protect their home against flooding, soil loss, and environmental threats. Common solutions include:
- Foundation piers to secure the home to bedrock and secure the structure against weak or shifting soils.
- Waterproofing to protect a basement or crawl space from water seepage and the hydrostatic pressure caused by ground saturation.
- Sump pumps with backup batteries to help homeowners quickly remove water during a flood.
- Drainage to help protect a home from water damage.
How can you protect your home from damage caused by soil loss or flooding? Find out with a free inspection from AFS.