costruction alluvial plains

think about it, interstitial water, variable particle size ledges. What can possibly go wrong?

In regards of interstitial water, do you mean that there can be bearing-capicity failure of the fundaments due to an accumulation of the pore water pressure?because that's the only thing I can come up with for the moment

I knew this woman once't who had one helluva fundament.

youre on the right track. What could happen to a single prism sitting on wet unstable soils?lots of places in alluvium have stability issues for construction.
do you know some of the means that we use to be able to safely build on alluvium?

Look at Mexico City or the Mission District and "Butchertown" in San Francisco.

I would say drainage and deeper fundaments in more stable groundlayers like sand. But drainage can also lead to soils subsidence if it is used on peatlands. I will look into your examples