Understanding Water Pressure in Mississippi Flooding and Levee-Dwelling Homes

[RickVS]

WRT the Mississippi flooding, you see pictures of homes with levees surrounding them that the homeowners built. It keeps the water out. Here is my question. The ground beneath the flood waters has to be soaked. Wouldn't this water permeate the dry ground right next to it under the levee like when a paper towel absorbs water and the water spreads as it gets soaked up? And if the ground under and inside the levee is soaked, then how come the enormous pressure of the surrounding waters don't just percolate up through the ground and fill in the area inside the levee until the water level, and pressure, is equal to the water levels surrounding it? These homes, for the most part, are bone dry, or at least dry enough to not pool water (with one exception that I saw, but even then it just pooled and that was it). Thanks.

 

[SpectraCat]

WRT the Mississippi flooding, you see pictures of homes with levees surrounding them that the homeowners built. It keeps the water out. Here is my question. The ground beneath the flood waters has to be soaked. Wouldn't this water permeate the dry ground right next to it under the levee like when a paper towel absorbs water and the water spreads as it gets soaked up? And if the ground under and inside the levee is soaked, then how come the enormous pressure of the surrounding waters don't just percolate up through the ground and fill in the area inside the levee until the water level, and pressure, is equal to the water levels surrounding it? These homes, for the most part, are bone dry, or at least dry enough to not pool water (with one exception that I saw, but even then it just pooled and that was it). Thanks.

I think that does happen, it just happens very slowly, and the floodwaters generally recede before it can happen to any appreciable extent. For example, the polders (reclaimed farmland that lies below sea level) in Holland need to be pumped out periodically to keep them dry.

 

[Studiot]

For example, the polders (reclaimed farmland that lies below sea level) in Holland need to be pumped out periodically to keep them dry.

We have an even more esoteric system where I live.

Good answer, by the way.

 

[pallidin]

Wouldn't this water permeate the dry ground right next to it under the levee like when a paper towel absorbs water and the water spreads as it gets soaked up?

Perhaps, but this is very site-specific. That is, the degree of permeation(thus saturation) is generally dependent on porosity.
Not sure about the area where your referring to, but I've seen ground with well over 70% solid rock, or large concentrations of solid gravel, or other soil conditions/compositions which do not lend themselves to ready saturation(due to extremely low porosity)