Heavy rains and surging waters can ravage a coastal community, and the examples of Hurricane Katrina and Hurricane Sandy are still fresh in the memories of millions Americans. According to a report from Climate Central, research suggests that instances like these are not likely to quit any time soon.

Hurricane Issac was a much weaker storm than Hurricane Katrina, and many citizens in the Gulf region believed that they couldn’t possibly see that amount of damage two times in a row. The surge generated by Issac, however was worse than anyone expected – it pushed 11 or more inches of rain quickly inland, causing Lake Pontchartrain to surge between 6 and 9 feet.

The rising water from the lake gushed into surrounding streets and homes because there was nowhere else for it to go. The surge was unexpected by many, and thousands of people needed to be rescued in areas with heavy flooding.

Compound flooding is a common happening in coastal regions, when the energy from a storm results in both massive amounts of precipitation and pushes the waves in the ocean forward towards the land. Over half of the country’s population lives in a region that could be affected by storm surges, with the most people on the Atlantic and Gulf coasts.

A new study analyzed historical data on precipitation events and storm surges, and found that the two were almost always occurring alongside each other.

Municipalities build and maintain seawalls and levees to protect themselves from the rising sea, but during a big enough storm they often come up short. As the changing climate continues to influence extreme weather events along the coasts, governments need to plan for mitigation strategies that address the risks posed by surging seas and heavy rains.