The amount and type of precipitation we experience on a daily or yearly basis can dramatically impact our lives and communities. Water is arguably our planet’s most important resource, affecting everything from daily human activities to business and industry, agriculture, and the environment.

Depending on your global location, your daily activities are generally dictated by either a lack or excess of water (drought or flooding). Over the past few decades, scientists have started to focus on the effect of a warmer atmosphere on precipitation rates. The consensus among experts is that the distribution of the world’s rainfall is shifting as our climate changes.

According to the Intergovernmental Panel on Climate Change (IPCC), “an increase in the average global temperature is very likely to lead to changes in precipitation and atmospheric moisture, including shifts towards more extreme precipitation during storms.” The consequences of shifting precipitation patterns could be far-reaching, so it’s critical for policy makers and community members alike to understand why and how this shift is occurring as well as what steps can be taken to move toward climate resiliency (the ability to anticipate, prepare for, and respond to hazardous events, trends, or disturbances related to climate) (c2es.org).

In a 2014 Summary for Policymakers, the IPCC stated that “warming of the climate system is unequivocal, and since the 1950’s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.” The Figure (a) below shows the trend of rising land and ocean surface temperatures since 1850 (ippc.ch).

Heavy rain showers present a greater threat at higher temperatures, as they maintain their high intensity over a more prolonged period of time.

Local evidence of a trend towards higher-intensity rainfalls can be seen in a comparison of precipitation frequency estimates for southeastern Wisconsin. For example, from 1990 to 2000 the SEWRPC 100-year, 24-hour precipitation depth increased from 5.50 to 5.88 inches and the 2-year, 24-hour depth increased from 2.4 to 2.57 inches. The most current rainfall distribution data (NOAA Atlas 14) shows rainfall depths increasing even further.

Locally, heavy rain events can overwhelm the existing storm sewer system, creating standing water and flooding in low-lying areas, roads, and on private property. This kind of extreme weather can cause private property and infrastructure damage as well as interruption to local businesses and community services. Even areas that do not suffer immediate flooding may be impacted if emergency vehicles are cut off due to flooded access roads. Downstream communities may receive additional floodwaters along river systems days after heavy rain events occur upstream.

Changing climate and weather patterns make managing water resources more challenging. While there isn’t a simple solution for planners and policymakers, resources like updated rainfall data reports, infrastructure system inventories, and modeling can assist in determining the existing and potential flood risk areas under specific rain events and duration. Your community can also take advantage of planning tools like the Institute for Sustainable Infrastructure (ISI)’s Envision Program which aims to guide communities towards climate resiliency via holistic and long-term planning.

Check out this video for a brief overview on ISI’s Envision Sustainable Infrastructure Framework.

For more information on municipal planning including flood studies, infrastructure assessments, and sustainable infrastructure planning, please contact an expert at R/M today.