We almost all have heard our mothers say, April Showers Bring May Flowers. While true, they also bring some dangers. Last week we discussed one of the more common weather threats, tornados; this week we will talk about flash flooding.

We almost all have heard our mothers say, April Showers Bring May Flowers. While true, they also bring some dangers. Last week we discussed one of the more common weather threats, tornados; this week we will talk about flash flooding.

Growing up in the suburbs of St. Louis, flash flooding did not present the hazards it does at the Lake of the Ozarks. Most likely one of the biggest reasons is the presence of paved roads with storm sewers throughout the county to handle rain waters. Moving to this area created a bit of learning curve regarding springtime rains and the hazards that come with them.

One of the more common calls over the years as it pertains to springtime is water rescues, not on the larger body of water of the lake itself, but the smaller tributaries. One road construction feature I had never seen in my early days that is prevalent in this area is lower water crossings. These low water crossing are an economical means of allowing vehicles to cross a creek bed by being constructed with culverts as opposed to bridges. These culverts allow water to pass under the crossing during normal flow; normal flow however is interrupted almost every spring.

When spring rains arrive, these creeks and rivers begin to flow above normal stage; runoff due to topography increases the amount of water in the beds and increases the flow, thus causing water to exceed the capacity of the culverts trying to divert water under the crossing. Once this water tops the crossing you have a dangerous situation, and in some cases a deadly one.

While I don’t want to bore you, we need to talk a little about physics. Water weighs 62.4 pounds per cubic foot and travels at an average speed downstream of 6-12 mph. When a car stalls while attempting to cross a low water bridge, the force of the water is then transferred to the car. For each foot of rise, 500 pounds of force is exerted to the vehicle. Remember as a child how items seem to be lighter in the water? Well cars are no different. Again for every foot of rise, the car will displace 1,500 pounds. Put simply your car weighs 1,500 pounds less with every foot of water rise.

Every foot of water adds 500 pounds of force to your vehicle while making it 1,500 pounds lighter. I think you can see where this is going. Add to this danger that this force of water also causes damage to the low water bridges, damage you can’t see when the roadway is covered with water.

Each year we run calls on these low water bridges for vehicles that have tried to cross but were unsuccessful. Over my years at the Fire District we have lost many cars and even people’s lives to this exact situation.

Please Know Before You Go, and never cross a roadway covered with moving water.