Should I build and ark?

We have been having some afternoon thunderstorms lately that have been real frog stranglers and I happened to be up in John's room during one of them. I thought I would try to capture the small river that flows through the back yard during heavy rains. My thought... it helps me identify where to plant a weeping willow. Really, the home inspector and I checked it out one day and we were both ok with the distance from the house to the river.