Why Harvey Will Keep Happening – And What We Can Do About It

Soldiers with the Texas Army National Guard move through flooded Houston streets as floodwaters from Hurricane Harvey continue to rise, Monday, August 28, 2017. More than 12,000 members of the Texas National Guard have been called out to support local authorities in response to the storm.
Soldiers with the Texas Army National Guard move through flooded Houston streets as floodwaters from Hurricane Harvey continue to rise, Monday, August 28, 2017. More than 12,000 members of the Texas National Guard have been called out to support local authorities in response to the storm.
U.S. Army photo by 1st Lt. Zachary West/Wikimedia Commons.

 

This week, Hurricane Harvey caused massive flooding along the Gulf Coast of Texas. Harvey’s flooding is unprecedented: A year’s worth of rain fell on parts of Texas in the space of a few days. Our thoughts are with the people of Texas and all who are responding to the extreme flooding with bravery and resolve.

Unfortunately, the scenes of devastation out of Texas are only just beginning. In the coming days and weeks, as the floodwaters recede, we will learn more about how this unprecedented rain event will affect people in the Gulf Coast. But we know the financial costs will be great, likely in the hundreds of billions.

Harvey is not, however, an isolated event. Rainfall amounts and such extreme flooding may be unprecedented in Houston, but we are increasingly seeing these kinds of extreme rain events all over the world, thanks to climate change. 

In India, Bangladesh, and Nepal, almost 41 million people have been affected by flooding and landslides.  More than 1,200 people have been killed in these floods, and continuing rains could worsen the situation.  More than a third of the country of Bangladesh, perilously close to sea level, was submerged by monsoon flooding. Nearly half of India’s state of Uttar Pradesh, home to 220 million people, was flooded.

Last month, over 120,000 people were ordered or advised to evacuate from their homes in northeastern Japan after record-breaking, heavy rain led to major flooding. The city of Akita received over 13 inches of rain in a 24-hour period. 

At least 56 people were killed in China in early July when rains caused the Yangtze River to flood and many of its tributaries reached record levels.

Climate change, while not the direct cause of hurricanes and monsoons, intensifies their impacts. Warmer air increases rates of evaporation, warmer seas contribute to an increase in atmospheric moisture. Warm air also holds more moisture than cooler air. That terrible collision of factors contributed to the intensity of Hurricane Harvey, and now Houston is suffering. 

Meanwhile, our actions over the last century to dam and channelize our rivers mean that when we do see such huge floods, the water has nowhere to go. Floodplains, wetlands, and free-flowing rivers are critical to reducing the impact of floods. And yet in too many river systems, our floodplains and wetlands are cut off and disconnected, undermining their effectiveness to deal with high waters.  

In the 20th century, the answer to dealing with floods was dams. But as we have seen this week, 20th-century water infrastructure is simply not able to cope with the 21st century’s extreme rain events. Our dams cannot handle water at these volumes. In Houston, two aging dams have left the Army Corps of Engineers with an impossible choice even as it was dealing with major flooding: release even more water, or risk the dams failing and a catastrophic release. 

The Netherlands, a country at severe risk from floods, has taken a different approach. They are creating “room for the rivers,” an approach that restores natural river habitat so that rivers can fully function and help to protect communities from flooding. The World Bank estimates that investing a dollar in flood protection saves $7 to $10 in flood damage.

More will be needed, of course. In vulnerable areas, locals will need to rebuild their homes to withstand periodic flooding. Utilities will likely have to decommission aging dams for the protection of all those downstream. And, perhaps most importantly, we’ll need to change our mentality. In the 21st century, it’s not a question of whether extreme floods will happen – it’s just a question of when.

Natural rivers are nature’s best defense against extreme flood events. In a changing climate, we can expect to see more extreme flooding like we are seeing now in Houston and have seen more frequently elsewhere around the world. To mitigate the floods’ impacts – the toll in human life, economic damage, and livelihoods destroyed – it’s time to protect and restore the rivers.

Date: 
Thursday, August 31, 2017