Watershed Texas

Houston has in place a natural flood detention and conveyance system that could handle another Harvey, sitting right here in plain sight. Our bayous, creeks, and streams, and their associated floodplains have carved out, over millennia, a very robust and capacious system. This legacy system did not fail during Harvey. We failed, over the years, because we put so many people in harms way. In fact, over 40% of all FEMA-designated floodplains in Harris County have been developed to one degree or another, with more than 500,000 homes and apartments in these hazardous zones. Few floodplains within the beltway are undeveloped.

[also at Gray Matters]

Where we saw boat rescues, where we saw 4 to 6 feet of water and more in homes, these were houses deep in harms way that should not have been there.

This legacy floodplain system was given to us free of charge. All we had to do was to protect it, to keep homes and commerce out of the low-lying valleys. Now here we are after Harvey, trying to reduce the size of the floodplains, trying to keep water out of the floodplains, because people and their homes are in the way now. Many great and beloved neighborhoods have sprung up in the floodplains. People don’t want to leave. And so they stay, hoping Harvey, Tax Day, and Memorial Day floods are just an anomaly.  We all wish it were so.

FEMA-mapped floodplains in Harris County. This is what our natural floodplain system looks like (but really even more expansive)

The dark blue and yellow areas represent development inside the floodplains.

Reclaiming our floodplains should be our number one task for reducing future flood impacts. Significant buyouts are contemplated for the 2+ billion-dollar flood-mitigation bond election scheduled for August. In fact, we may see many more buyouts that we have ever seen before. But I am afraid this is just a small down payment on real floodplain reclamation.  Twenty-thousand homes, perhaps a very conservative estimate of seriously flooded homes, at $200,000 each (not quite the current median home price), comes out to $4 billion dollars. Likely significantly more is needed. Twenty billion dollars would allow us to reclaim 100,000 floodplain homes. That would buy us some real resilience.

How much ever money it is, it needn’t be money that flows out of the system. If we help guide those funds to the construction of new homes and communities on higher ground, then those billions of dollars would be a large and significant stimulus to our economy. And that newly freed-up greenspace would in no way be a drag on our long-term economy. Large, sinuous greenbelts could provide space for many activities, including sports grounds, allotment gardens on scales never before seen, and natural areas for hiking etc. The economic value that these kinds of greenspace bring is well documented in the literature.

Reclaiming our floodplains is the work of a generation or two. This is not something that can take place overnight. It’s not just the money—it’s about homes and a sense of place, and painful displacement. But this is a transition we must make, however slowly, for our long-term resilience.

Another Harvey is on the horizon—sometime, somewhere.  A Tax Day flood—as inevitable as its name suggests, will likely occur much sooner. We should be developing plans now for floodplain reclamation following storms to come.  We may have missed the boat on Harvey, in terms of large-scale reclamation. These kinds of decisions have to be made before hand, not during or even soon after a catastrophe. These decisions must be made in consultation with the people to be affected, in a sober and serious way.

This “modest” proposal is not meant to dismiss the significance of upland or sheetflow flooding.  Just about anywhere in or region is so very flat that some kind of imposed drainage on the landscape is necessary for us to be able to live here. Without engineered drainage, even a 2 or 3 inch storm could make life difficult in the uplands. But this kind of engineering is very different from that required to reduce the size of our natural floodplains, which is what we have been doing for the past 60 years or so. Lets also not forget that our floodplain manipulation efforts for the most part have been designed for 100-year storms. Now we know that the 100-yr storms might just be a bit larger than we have imagined them to be thus far.

Floodplain reclamation is a moon-shot kind of effort. But we shouldn’t think of it only as correcting past mistakes, though it surely would be that. It is much more about making Houston a resilient city that embraces the nature of its place.  We could truly live up to being the Bayou City, a great and vibrant city with riparian greenbelts like no other. I may not live long enough to see that, but I want to help that vision become a reality for my grandchildren and their children.  This is my place, and theirs.