One thing to think about in your planning is the immense power of moving water. Even though the water level may not reach above the top of your foundation, if that water is moving at any speed it can easily erode the support out from under your house. Never underestimate the power of moving water! Check out this scary video!

Likewise, you might run into trouble if you try to evacuate after the water is across the road, even if it seems shallow enough to drive through. Lots of people have died trying to drive through moving water that seemed shallow enough to ford.

You might want to do some research into how fast water is moving when your river and ditch are in flood stage. If there are any gauging stations anywhere along the river, find out what the discharge is at flood stage. Also, talk to any old timers around. And look into the history of the area. You want to get an idea of what was the worst flow that has ever occured in the area, even before your familly owned the property. The "hundred year" flood plain is often just an educated guess by hydrologists. Hydrologists do the best they can with the data they have available, but always assume those estimates could be wrong. Allow yourself a margin of error!