Field Notes

By Jed Harvey and Abby Phinney, Lilly Center Staff

Every year, warm weather comes around April and May, and with it comes rain… and often, flooding. Spring thunderstorms bring the renewal of woodlands, the sprouting of fields and the ever-present cycling of our county’s many lakes and streams, but it can also be a harbinger for property damage and human health risk. Flooding ruins yards, submerges basements, and washes away crops, property and even cars and people.

Needless to say, flooding is a serious and important topic. The first step to preventing loss of property or life is understanding what a flood is, and we want to help define this common spring and summertime event so you can be knowledgeable, prepared and safe.

What is a flood?

Floods are a common natural disaster, a frequent force of nature. Floods can be small and harmless or massive and deadly. Since time immemorial floods have affected people and cultures. The Nile’s yearly floods brought life to the lands of ancient Egypt, and the Yellow River’s periodic floods has caused tremendous damage and loss of life in China. Throughout history floods have shaped civilizations and influenced people, from Noah and his Ark to the Akkadian hero Gilgamesh to the Norse deity Bergelmir.

But those are all major, region-wide or world-wide floods. Here in northern Indiana, we deal with smaller floods, and people don’t often have to build a boat or gather two of every animal to survive.  

In our region, floods are caused by two main phenomena. When there’s more water than the ground can soak up or the streams can hold, flooding occurs. Water spreads and remains in areas where there shouldn’t be standing or flowing water (think about the “ponds” that appear in fields.) Rain and melting snow are the two main natural causes of this, but it can also happen due to dams or levies breaking.

Flooding also occurs near streams when more water enters the stream than can flow away, causing the water level to rise and go over the banks of the stream (these are called “fluvial floods,” which is very fun to say.) Floods happen in open areas when the ground can’t absorb water as quickly as the water is coming, causing water to sit on top.

Flash flood or just plain flood?

Floods, like any type of natural event, come in different forms. We most frequently hear about “floods” and “flash floods”. These names are slightly confusing, so here’s a simple way to understand the difference:

Floods (plain ole floods) are slow. They usually occur after precipitation has passed. Flood waters rise slowly due to incoming water in addition to the water already gathered due to the rain or melting snow.

Flash floods, on the other hand, are fast. During flash floods, the floodwaters rise quickly and often without warning. They occur during or within six hours of the rain falling or snowmelt occurring, and often flow from one area to another quickly.

Who is at risk for flooding?

If you live in an area that traps water easily, it is especially important to plan for flooding; being caught unprepared can be dangerous. Flooding is most likely to occur in flood-zones, areas that have been determined to be at just the right place in the watershed for water to gather, or near streams or lakes that water will most likely spill into when the levels reach flood-stage.

That being said, flooding is a risk for everyone, not just people in flood-zones. Everyone should do a few minutes of research to see if they’re in a flood-prone area.

There are many useful resources to help determine if you live in an area susceptible to flooding. Flood plane maps are widely available, and newer government websites often pull sources together to have comprehensive risk maps accessible to everyone (here’s an example).

Ways to prepare for flooding

Preparing for floods is something everyone should do to some extent, even if they don’t live in a flood-prone area. Like all weather-based events, an influx of water is difficult to predict and sometimes isn’t recognized until it’s happening. A big flood can reach far outside of what maps predict. Getting caught off-guard is far worse than doing a little preparation for a flood that doesn’t happen! To help make preparation easier, we’ve condensed best-practices from the National Weather Service into three main steps:

1. Know what is coming: Keep an eye on the weather, and know when storms or heavy rain might come. A simple, hands-free way to do this is to have an emergency alert radio in your house; it will warn you about flood warnings as soon as they are released. (We suggest that you still do your own research to know when bad weather is coming, though!)
2. Have supplies: Keep nonperishable food and bottled water in a safe, waterproof place that’s accessible in case of emergency. Flooding can cause utilities to go out and roads to be flooded (more on that later), so it is important to have an emergency supply enough for a few days on the off-chance a massive flood happens. Also, keep important documents, like passports, financial information and legal documents stored in a waterproof container. And finally (especially if you live in a flood-prone area) consider investing in a battery-powered sump pump.
3. Have a plan: Know what to do if a warning is announced. Know where to go and what not to do, too! You may also consider flood insurance, just in case.

There are a lot of things you can do before and during a flood, but most are the important things you should not do. It may seem like common sense, but the misconception that these things aren’t dangerous has cost people their lives. The two most important don’ts are:

• Do NOT walk through floodwaters! Flooding can cause walking to be very dangerous. It only takes six inches of water to knock down an average person, and floodwaters are usually muddy and full of sediment. Debris can be hidden beneath the surface, just waiting for you to trip. Floodwater also can cause the ground to become unexpectedly mucky and soupy, or just wash it away entirely. Tripping or falling into floodwater can cause someone to get stuck underwater or washed away. Never walk through floodwater.
• Do NOT drive in floodwaters! Driving in floods accounts for half of all of the deaths that happen due to flooding. It’s far too easy for water to get under a car’s tires and push it into a river or deep flooded pool, trapping the passengers inside. If there’s water on the road and you cannot easily see the pavement below, or if you can and can tell it’s deeper than your tires can handle, do NOT drive into it!

The bottom line is simple: Keep yourself and your family safe during bad weather by making sure you’re prepared for the unexpected. Even if flooding is unlikely in your area, it’s always better to be equipped with the right information and action steps!

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For more information, see the National Weather Service’s articles on flood safety: weather.gov/safety/flood