If you're not from Arizona, it may be hard to believe that we get rain. During the annual Monsoon season, Arizona gets a LOT of rain. When the rain comes, it's hard, fast and all at once. In recent weeks, Arizona experienced a very large rainstorm and here is the aftermath.
As you can see, there is a vast difference between areas of controlled runoff collected in large retention basins and areas of uncontrolled runoff. Uncontrolled runoff creates washouts, scour and rutting, which can be very costly to repair. This is why it is important to ensure that every single stage of site design and construction has an appropriate engineered hydrology study and not just in Arizona.