Hurricane Harvey wreaked devastation across Texas last week. After having endured flooding of my home in Louisiana just one year ago, my family and I watched the water slowly rise once more as it rained for days and days in the Houston area. The water didn’t come into our house this time, but it did flood many of my friends’ and colleagues’ homes, not to mention hundreds of thousands more homes across Texas. As in Louisiana last year, the refrain of “but it never flooded here before” was common.
We often call natural disasters “Acts of God”—that is, extreme weather events or other natural phenomena over which humans have no control. And indeed, much of what happened with Harvey and every other hurricane or similar disaster is indeed beyond human control. The record amount of rain in such a short period of time was astounding. The chances of a high pressure system holding a storm of that magnitude in place for so long, dumping all of that rain, are low. Yet it happened. And we could do nothing to stop it.
Yet, what makes a natural disaster a disaster is that people are harmed. Sometimes society makes decisions that place people in the path of destruction. Of course, people must live somewhere. And bad things will happen beyond our control no matter where we live—so-called Acts of God. Yet societal decisions that place people in the path of harm are Acts of Man. The foremost Act of Man that we might discuss in the context of Harvey (and Irma who followed closed behind it) is the increased hurricane strength due to climate change. Just as one data point, with every degree Fahrenheit rise in air temperature the atmosphere can hold and dump an additional 4 percent of water. This undoubtedly contributes to the fact that “nine of the top 10 years for heavy downpours in the U.S. have occurred since 1990.” But I want to focus on another Act of Man, and one over which we exert perhaps the most direct control—at least in the context of flooding: how and where we develop our land.
Consider where I live, in Kingwood, TX. The series of pictures below demonstrates how poor land use planning contributed to the increased flooding and devastation from Harvey. These side-by-side comparisons were captured using the Google Timelapse tool, which compares satellite data from 1984 to the present. Most of the flooding in Kingwood resulted from a surge of water coming down the San Jacinto River and bottle-necking as it tried to flow into Lake Houston. In the first image, you can see Kingwood outlined in the red box. The path of the San Jacinto can be seen at the bottom of the red box, winding its way into Lake Houston. In this comparison you can see just how much green space has been replaced by concrete and other “hard” developments between 1984 and 2016. This means that less water is able to percolate through and be absorbed by the soil or by wetlands, and more water is therefore channeled into drainage ditches that become increasingly overwhelmed during flood events. More importantly, when housing and other forms of development are placed so near major waterways in natural watersheds—which of course fill up and overflow during heavy rain events—more people and their property are in harm’s way. And in this picture you can see clearly that housing developments creeped ever-toward the San Jacinto on both its north and south sides over this 32 year period.
And while Harvey would have been a disaster and would have harmed humans no matter what, better land use planning could have resulted in fewer people being placed in the direct path of flooding. Charles Marohn, a licensed engineer and a certified land-use planner, recently opined in the National Review that the media wrongly spins natural disasters, like Harvey, into narratives that support political causes—narratives that he claims belie the facts. He asserts that the claim that “[f]illing of wetlands and sprawling development patterns are the reason Harvey was so devastating to Houston” is false. He does acknowledge that sprawling development and the filling of wetlands do lead to increases in flooding during typical flood events. But he states that Harvey was anomalous because it was “simply a huge storm” that dropped so much water onto Houston that even the most robust wetland preservation or land use policies would have been unable to prevent flooding. He states “[a]nyone suggesting that more wetlands or more pervious surfaces would have done anything to mitigate what has just happened is lacking a proper sense of scale.” And this is where the strength of Marohn’s analysis falls apart. The accurate part of what Mr. Marohn is saying is that the storm would have been devastating no matter what. And that the storm dropped more rain than even the “greenest” version of Houston would have been able to handle without flooding. I do not believe anyone is arguing contrary to those assertions, and so Marohn has successfully set up a straw man. But just because Harvey would have been devastating no matter what does not mean that some of that devastation could not have been mitigated. If Houston had a better approach to land use planning that took greater care regarding the placement of residences in or near major drainage areas, the storm could indeed have been far less devastating.
While natural wetlands would not have absorbed anywhere near all of the rain that fell, wetlands and forests in low-lying areas near waterways are great demarcations of watersheds, and in turn, where we should and should not build our homes and businesses. Though many homes and businesses flooded along these waterways—Houston is a city of 6 million people—some relatively slight adjustments in the siting of homes in floodplains could have dramatically reduced the number of homes that flooded.
Consider the following images from Kingwood. Virtually the entire land area outlined in the red boxes below flooded. Compare the two images in the oval.
In the 2016 oval you see a neighborhood called Barrington, which was built fairly recently. Importantly, Barrington, again depicted in the red oval below, is well within both the 100 year (light blue) and 500 year (light green) floodplain according to FEMA flood maps:
All 270 or so homes in Barrington flooded. The neighborhood’s drainage flows into the San Jacinto, so when the river rose to a record level during Harvey (though not much higher than it did during a record rain event in 1994 before Barrington was built) the water had no where to drain and flowed backward into the neighborhood. When the area was a stand of forestland, up until about the year 2000, this was not a problem. But a failure to engage in responsible land use planning caused 270 more homes to flood. The same is true of the hundreds of homes and businesses that flooded in the area at the end of the arrow in the two images above. Considering that the flooding stopped just north of the red box, we can fairly call these man-made failures, not failures outside of our control and caused solely by Harvey. Would some homes in this area still have flooded if these two areas had not been developed in the last few decades? Yes. But 500-700 or so fewer families would be displaced in this one suburb of Houston alone had local governments and land use planners preserved a greater buffer zone around the waterway.
Consider another example in the next image. A Costco store, a Laser Tag/Bowling/Video Arcade facility, and numerous other businesses inside the red square—developed beginning in 2015—flooded completely during Harvey. It is, again, no surprise given their proximity to the San Jacinto River. Areas just south of these locations did not flood, meaning that there is a reasonably discernible buffer zone outside of which we could have made it less likely that human developments would suffer harm during Harvey.
If society did utilize more stringent land use planning policies to better discern and protect buffer zones in drainage areas and watersheds, will we get those zones’ proper location wrong at times? Of course. Some places outside the zone may flood despite our best efforts, due solely to the nature of a storm. Other property that we declare to be in the zone may never flood, and so some people might decry the supposed economically “inefficient” non-use of land. But given the state of knowledge regarding climate change, more accurate floodplain demarcation through complex scientific modeling, and numerous other data points readily available to us before these developments occurred, the devastation wrought in these areas was largely a result of society’s lack of political will to better regulate how certain lands are used—or not used. What happened in Kingwood happened all around the Houston metropolitan region, and it was the aggregation of these poor land use decisions that compounded the tragedy wrought by Harvey. These were Acts of Man. And Mr. Marohn and others who share his perspective can’t blame Hurricane Harvey for that.
– Blake Hudson