As coastal areas around the world become more populated, the risk of death and destruction from flooding increases.
Flooding caused by heavy rains in and around Houston, Texas, in mid-April resulted in at least eight deaths and damage to more than 1,000 homes. Severe weather and flooding over the past weekend left at least four other people dead as well.
With the start of the hurricane season June 1, officials are preparing for the possibility of more floods.
Last week, a group of west Houston residents filed a lawsuit against the city over commercial development projects they allege were approved without requiring measures to deal with stormwater.
Their complaint goes to the heart of the question of what constitutes a natural disaster and what constitutes a disaster resulting from failure to plan and prepare for natural occurrences.
Around the world, cities are mostly located on sea shores, lake fronts or on the banks of rivers for commercial transportation purposes. But as sea levels rise and storms grow more intense, crowded urban areas will be more vulnerable to disasters.
The more than $70 billion cost of Hurricane Sandy, which struck the northeastern U.S. coast in October 2012, came from damage to homes, buildings and the infrastructure that serves the region’s dense population.
Houston is one of the least-dense cities in the world. However, U.S. Census figures show the city, and its surrounding area, is one of the fastest-growing urban centers in the United States, resulting in more roadways and buildings covering the land near rivers and creeks that drain into the Gulf of Mexico.
Samuel Brody, a professor at Texas A&M University, said this contributes to the flood risk.
"We tracked, over a 15-year period, a 25 percent increase in impervious surface coverage, pavement, in the Houston region and that translates into more people and structures in harm’s way and less opportunity for rain water to infiltrate into the soil and then it runs off, potentially into people’s homes," Brody said.
Houston's location makes it vulnerable anyway, said Francisco Sanchez of the Houston Office of Emergency Management.
"One of the challenges is where we chose to build Houston, which is essentially on a swamp and it is also close to the gulf coast," Sanchez said.
He noted that lower areas hit with unusually strong downpours had the worst flooding.
Mike Talbot, executive director of the Harris County Flood Control District, said the district is clearing houses out of susceptible areas and building them to higher ground.
"That has actually been the criteria for the past three decades, that homes are built above the 100-year flood level," Talbot said.
Moved to higher ground
He said the Flood Control District and FEMA (Federal Emergency Management Agency) have acquired more than 3,000 homes in the flood plain and relocated people to higher ground, l, and now that is open space," Talbot said.
However, despite these efforts, experts said lives will still be at risk if citizens fail to understand flood risks.
Talbot noted that of the people who died in recent flooding, none were killed at home; the victims had been out in the storm and drove into a flooded area, such as an underpass.
Experts said public awareness of flood dangers is critical to saving lives.