Hurricane Seasons, Erosion, Rising Seas, Sinking Land Mass

[NewsCopy]

Think of a major city in the United States. Chances are, its land is slowly sinking.

A new satellite radar study has now found evidence that the nation's 28 most populous cities are all buckling under the pressure of urbanization, drought, or rising sea levels, to varying extents.

Science Alert

[VObserver]

Think of a major city in the United States. Chances are, its land is slowly sinking.

A new satellite radar study has now found evidence that the nation's 28 most populous cities are all buckling under the pressure of urbanization, drought, or rising sea levels, to varying extents.

Science Alert

Subsidence in many of those cities is a direct result of population growth and changes in lifestyle. The major losses of open land in urban areas, that loss being due to covering much of the urban area with concrete or asphalt, greatly decreases the volume of rainfall that is absorbed in the ground. Combine that with massive increases in withdrawal from groundwater aquifers, and land will subside rapidly.

[Turbine]

In the past 125 years Mexico City has experienced over 60 feet of subsidence due to aquifer depletion.

I put near zero credence into the extra weight theory.

VO's point about urban terrain preventing aquifer replenishment that is 100% valid.

You saw this on Louisiana's alligator habitat 115 years ago when it dried up due to new ditches all over campus preventing the pooling of water.

[60swerethebest]

Some subsidence, as in SE LA, can be due to the high organic content in the upper soil levels. Any load causes significant subsidence. We added 6 yds of soil to our Metairie yard every year. One could literally see under our slab which rested on piling. Miserable to maintain a yard.
Agree on Houston and Mex City. Overuse of the underlying aquifer is main culprit.

[HelmutVII]

There is the Houston Galveston subsidence district which highly regulates water well drilling in that area. There is a permit fee to drill and a per thousand gallon fee that they charge. It is different for residential, commercial and industrial. If memory serves me right. The disincentive fee for industrial is greater than the cost of deslanization. They want to encourage the use of Gulf water for industrial use.

Since we have been using GPS for surveying. We have found that the land in rice growing areas can subside as much as 12 to 18 inches during rice flooding season. It rebounds when they stop pumping. The area from the coteau ridge to the east all the way to New Orleans is, geologically speaking, a new born. Not even in diapers. It alluvial deposits with high voids ratio filled with water. The general rule of thumb is the subsidence is 1.5 cm per year. If that is not replaced with spring flood deposits then we are behind.

Our Subsidence situation along with poor soil characteristics is manifested in the poor condition of our roads.

[Turbine]

There is the Houston Galveston subsidence district which highly regulates water well drilling in that area. There is a permit fee to drill and a per thousand gallon fee that they charge. It is different for residential, commercial and industrial. If memory serves me right. The disincentive fee for industrial is greater than the cost of deslanization. They want to encourage the use of Gulf water for industrial use.

Since we have been using GPS for surveying. We have found that the land in rice growing areas can subside as much as 12 to 18 inches during rice flooding season. It rebounds when they stop pumping. The area from the coteau ridge to the east all the way to New Orleans is, geologically speaking, a new born. Not even in diapers. It alluvial deposits with high voids ratio filled with water. The general rule of thumb is the subsidence is 1.5 cm per year. If that is not replaced with spring flood deposits then we are behind.

Our Subsidence situation along with poor soil characteristics is manifested in the poor condition of our roads.

Long suspected the rice growing area numbers.

Did not expect the bounce back numbers due to so much clay and runoff. Thats encouraging.

Yep, Louisiana roads are buit on jello.

[HelmutVII]

Long suspected the rice growing area numbers.

Did not expect the bounce back numbers due to so much clay and runoff. Thats encouraging.

Yep, Louisiana roads are buit on jello.

They are pumping water from a sand aquifer not the clay/silt overburden. When they stop pumping the aquifer recharges lifting the overburden.

[Turbine]

They are pumping water from a sand aquifer not the clay/silt overburden. When they stop pumping the aquifer recharges lifting the overburden.

Made my day.

I still think Louisiana should employ some "Cajun Nova Scotia Know How" with land reclamation.