Rainfall is increasing and becoming more intense as the climate warms. The rising temperatures cause more water to evaporate into the atmosphere and fall back on landscapes. (Darrell Hoemann / Investigate Midwest)
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This story is a product of the Mississippi River Basin Ag & Water Desk, an editorially independent reporting network based at the University of Missouri School of Journalism in partnership with Report For America and funded by the Walton Family Foundation. Wisconsin Watch is a member of the network. Sign up for our newsletter and donate to support our fact-checked journalism.

The Mississippi River Basin Ag & Water Desk asked for audience questions and perspectives while reporting its new series, When it Rains, which shows how increased and intensifying rainfall is impacting communities and agriculture throughout the Mississippi River basin.

Here are answers to some of those questions.

What patterns do we see in rainfall and flooding along the Basin?

Our reporting found that rainfall is increasing in the Mississippi River basin by up to 8 inches a year, especially in the Midwest. Rainfall is increasing as the climate warms. More water evaporates into the atmosphere and falls back on landscapes. That rainfall is also becoming more intense, dropping more rain over a shorter period.

Flash flooding in St. Louis, for instance, broke a century-old rainfall record this summer. Increased rainfall overwhelmed the main water treatment facility in Jackson, Mississippi. Historic flooding left eastern Kentucky communities decimated.

This graphic shows the process by which warming temperatures cause increased and more intense rainfall. (Courtesy of Climate Central)

What caused the huge amount of flooding we saw this summer?

Flood risks can vary widely from place to place, but can be especially pronounced in small, “flashy” watersheds that are unusually sensitive to bursts of incoming water. One of the epicenters of damage near St. Louis this summer, for example, occurred along the upper stretches of the River Des Peres, a highly urbanized waterway that experts have identified as Missouri’s most flash-flood-prone system.

The river essentially acts as an urban drainage ditch, converted largely into a straightened concrete sleeve that can be easily overwhelmed with water funneled from surrounding pavement and other impermeable surfaces.

Some similar factors are at play in Appalachia – another epicenter of this summer’s flood damage. There, rugged terrain leaves homes to be built almost exclusively along rivers and at the foot of mountains. The steep slopes allow water to travel quickly to the residents below.

Does environmental damage from oil, gas and coal extraction exacerbate flooding in legacy fossil fuel communities?

It can. Any kind of development can increase flood risk, as it decreases the land available to absorb floodwaters. In Appalachia, for example, the region’s history of strip mining and mountaintop removal contributes to the danger. The damaged land is often unable to soak in water as it naturally would. Even remediated mine lands often consist of compacted soil and grass, which aren’t ideal for flood mitigation.

Will heavy rains like this become more frequent?

Scientists say yes. The threat looms particularly large across the Eastern United States — encompassing the Midwest and much of the Mississippi River Basin — which is seeing more intense downpours than it used to. That’s because it receives moisture from warming water bodies, in particular the Gulf of Mexico, as oceans heat up, due to greenhouse gasses in the atmosphere.

What measures can prevent flooding while also preserving natural landscapes and ecosystems?

Some communities are opening up floodplains, creating space for the water. Cities and towns can enact building restrictions to limit development in flood-prone areas. Governments also buy flood-prone properties, letting residents relocate to safer locations while converting the areas back to green space.

Research has found that these nature-based solutions successfully mitigate flooding. Proactive buyouts provide permanent solutions for communities in harm’s way. When paired with those buyouts, levee setbacks reduced flood risks in every studied scenario in the Mississippi River. The resulting floodplains offer opportunities for recreation, ecotourism and increased ecosystem services.

What can I do to prevent flooding in my basement?

The Federal Emergency Management Agency recommends taking a variety of steps, which include sealing any cracks in the foundation with mortar and masonry caulk, or hydraulic cement; sealing basement walls with waterproofing compounds; installing a sump pump; and utilizing drain plugs for basement floor drains.

This story is part of When it Rains, a special series from the Mississippi River Basin Ag & Water Desk, an editorially independent reporting network based at the University of Missouri School of Journalism in partnership with Report For America and the Society of Environmental Journalists, funded by the Walton Family Foundation.

Republish our articles for free, online or in print, under a Creative Commons license.

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