The damage was not caused by flooding so much as by erosion. Erosion is a major danger along the Matanuska River and along other glacial streams in the Alaska. These rivers do flood occasionally, as can be seen inthe photo to the right, but they more often erode their banks taking away land that may have been untouched for centuries.
If you purchase property next to one of the glacial rivers that are running in a braided stream be aware that these streams constantly fill up their beds with sediment and shift to the right or to the left. If they shift far enough they will reach the extreme of the river bed and erode the banks. A house can be 100 yards from the river one year and drop over the bank the next.
The house above was stuffed into a dumpster yesterday, see below, make sure you build your house on a rock or at least away from a glacial braided stream to avoid the same fate.