Phoenix declared a disaster area three times. Two larger peak discharges in the same week were not noticed. Areal Extent of Floods in Arizona. Click to view larger image. Arizona has both local and regional floods.
Local floods occur most frequently.
Local floods occur primarily in basins of less than about 100 mi 2 because the area affected by an individual thunderstorm is small. Cumulative damage from local floods can be substantial, even though a single flood rarely causes much damage. Local floods cause several drownings annually in Arizona. Eight people were killed. These larger peaks were not noticed by the public and caused no damage because no one had been at risk on the canyon streambed when the peaks occurred.