The Colorado River Irrigation District in Mexicali has suffered extensive liquefaction of the water infrastructure. According to the wiki:
Soil liquefaction describes the behavior of soils that, when loaded, suddenly suffer a transition from a solid state to a liquefied state, or having the consistency of a heavy liquid. Liquefaction is more likely to occur in loose to moderately saturated granular soils with poor drainage, such as silty sands or sands and gravels capped or containing seams of impermeable sediments. During loading, usually cyclic undrained loading, e.g. earthquake loading, loose sands tend to decrease in volume, which produces an increase in their porewater pressures and consequently a decrease in shear strength, i.e. reduction in effective stress.This year's crops are mostly lost. I wonder how to rebuild the infrastructure to resist future earthquakes. The pic shows how the increased soil water pressure during an earthquake expulsed sewage manholes from the earth.
3 comments:
Normally orverpumping groundwater in urban areas is a bad thing, but if constant pumping can lower the water table it could potentially make the city safer during an earthquake.
Arrghh! It's overpumping, not orverpumping.
Although, on second thought engineers create so many specialized and often unnecessary terms for their field that orverpumping might actually be a legitimate water engineering term.
Whagtever.
The concept is correct - lack of drainage caused the liquefaction phenomenon in Mexicali and the loss of many crops. It also affected the North American side of the Colorado river infrastructure. I told my Mexican collegues that they cannot practice irrigation without a parallel system of drainage.
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