Why do we flood?

Every drop of rain has to go somewhere. For most stormwater in Lafayette Parish the final destination is the Vermilion River. The land it travels along the way is called a watershed, in our case the Teche-Vermilion Watershed. 

The defining character of our watershed is a lack of elevation. Lafayette to the Vermilion Bay is flat, and it gets a lot of rain about 62 inches a year, nearly twice the U.S. average.  

The path it travels is ultimately decided by where it falls. Rain that lands on soil is likely to stay there, but when rain falls on roofs, roads and parking lots, it flows into a network of drainage channels, usually through storm drains and ditches. 

Lafayette’s drainage system is divided by its coulees and ditches into countless micro watersheds, most of which eventually drain into the Vermilion River. Those individual channels act as one interconnected drainage system in larger storms, meaning that bottlenecks in one area can lead to rising waters upstream. 

Stormwaters rise when they can’t flow downstream. So the goal of any successful drainage system is to move stormwater away from floodable structures. 

When water overloads those channels, we flood. That’s happened more and more in recent years. And flood risk has largely increased for Lafayette as a whole. Researchers project it could get even worse.