By the time you’re reading this, it will be history. The Great Bangkok Flood of 2569 (2026) will have (hopefully) receded and I won’t be stuck in the house. As I write this on Monday morning a total of some 300mm (twelve inches) of rain has precipitated onto the central plains of Thailand, including Bangkok. This rainfall, with the bad timing associated with disasters in general, occurred near the end of the rainy season which left the thin layer of soil between the surface and water table already saturated. The new three-day deluge – a total of 20% of Bangkok’s typical annual total – had nowhere to go.
So it didn’t.
And it’s still raining.
So, yeah, hopefully.
The problem is multifaceted and the lack of a solution is always blamed on The Government. Were it so simple. There’s a similar, annual problem that also directs the people’s ire at The Government: the burning of crop residue and forest understory. This burning, along with that in neighboring countries, lays waste to the air quality over most of the country and results in the finger pointing associated with popular ire. So, every year, the burning commences as soon as it is dry enough to do so, peaks in February and March, and ends at the beginning of the rainy season as the new rice crop gets planted. The ire is never directed at the people doing the actual burning, though. By the end of the rainy season – recently rebranded the “Green Season” by the Tourism Authority of Thailand – the smoke has been forgotten, but the ire has not.
Which brings us back to the GBFO69.
Thailand floods. Full. Stop. It floods in the north. It floods in the south. And it floods in the middle. But these floods are almost never a surprise. This flood was. The typical progression is that rains in the north and north-central areas fill the rivers that join north of Bangkok to become the Chao Phraya, Thailand’s big river. This process takes weeks. Along the way, reservoirs are filled, agricultural areas are flooded as a buffer, and diversion infrastructure is readied to sidetrack the inflow around Bangkok. In Bangkok itself, the endless canals are pumped down to provide an additional cushion. But this year the river didn’t play much of a role. The system that moved through central Thailand was expected but nobody counted on the massive volume of water the system would bring to Bangkok and the lower central plains.
It was a surprise.
The land was soaked. The canals were nearly full. And it started raining.
The second thing that humans are very bad at is scale. The first is complexity. Nobody thinks that their tossing of a McDonald’s bag out the window is a big problem. And they are right. But they forget that the other eight billion people on the planet might also be tossing their whatevers out of a metaphorical window and then start pointing fingers once the trash starts piling up. But since we humans are terrible at imagining big scale problems we focus on the small scale we can get our minds wrapped around. This always causes us to rationalize that we didn’t cause the problem so it’s got to be somebody else’s fault. When this personal non-responsibility meets complexity then the fingers get pointed but never back at the person in the mirror.
So, what was the scale of the GBFO’69? Huge. Looking only at the lower Chao Phraya river basin, an area of roughly 37,000 sq km (14,400 sq mi) and assuming an average of 200mm of rain – instead of the 300mm recorded in Bangkok – that gives a total volume of 8.14 cubic kilometers (2 cubic miles) of water that fell within a couple of days in and around Bangkok.
To put that into a perspective imagine an aquarium that’s 2km (1.3 miles) on a side.
But that large-scale picture is not my problem. My problem is the much smaller area that is drained by the Phra Khanong; a canal that extends from the river about 15 kilometers inland and is the catchment for smaller canals that drain a much smaller 360sq km area. Here, unfortunately is where that 300mm rainfall number is more accurate, and the total volume of water, a mere 0.11 cubic kilometers, has but one path to the sea.
All that water is flowing into a saturated system which, at the best of times, requires that the stars align to work well. The rainwater drains into the storm system and local ditches. These then flow into the canal. And then the canal gets pumped into the river. And that river flows into the sea.
But.
Through no actual fault of The Government there are these things called “tides”. They go out. They come in. And when they’re coming in the river reverses direction and saltwater flows in.
And, as you guessed it, the nice freshwater floods need to be pumped into a river that won’t be flowing into the sea. At least not for a few more hours. And, because nature abhors a vacuum of irony, the high tides are getting higher right now. Over 3m (10ft) at Bangkok, which makes the whole “water flowing uphill” thing even more of an issue.
With the whole chain of drainage backed up at its destination plus the new influx of water that fell two days out of town now arriving, the water level in the canals stays, well, level. This keeps the storm drains full and allows the roads and streets and alleys of Bangkok to become a habitat for fish. Of which I just saw two right out in front of the house.
It, of course, is never all bad news. The rain is decreasing in frequency if not intensity. It is still the rainy seaso… oops… Green Season, so some precipitation is expected. It’s not always high tide so the pumps can make some headway. And they try. The pumps that are handling the roughly one-hundred eleven millioncubic meters of water that they’ll have to deal with can move a mere 175 cu-m/second. Which is a lot when you’re standing right next to it but will still take about ten days to get us back to where we were on Thursday morning. What with the tides and all.
Yes, there is a time where the streets are dry, and the fish have been shoveled up. The shelves at the 7 – 11s will be restocked and life will return to what passes for normal in these parts. Businesses will reopen and the indispensable food delivery drivers will be able to make it back into our neighborhood.
Before that we, at the mercy of the tides, the rain gods, and whatever other malevolent spirits make people go out into the flood in their Bentleys – no, really – have to make do the best we can. The canals, at high tide, back up until they’re above street level and the cycle, albeit at a slightly lower level each day, repeats. Water flows in, the tide goes out, water gets pumped out.
It’s like the Circle of Life.
Yesterday, at last, the water in the ‘hood finally dropped to about 30cm in the deep parts. I was able to take my scooter out to meet a delivery driver who didn’t want to risk his scooter on the floods. It was, refreshingly, kind of a wet ride and I got to see the Phra Khanong – our aforementioned local big canal – at full flood. Water was bubbling into the street marking the start of the next flood-wait-pump cycle.
So, yes, in part it’s The Government’s fault. They are the ones that built and maintain the drainage systems, the pumps, and all the hundreds of little things that go into keeping that all running. It’s their fault that the floods drained away in a few days instead of the weeks it would have taken if gravity were left in charge. And it is their fault that the drainage systems were designed to handle a worse-than-typical 80mm of rain instead of the arkean 300mm that caught everyone by surprise.
What The Government had no blame in were the tides and the rain.
But the government here has, as do all governments, pretty thin skin. And today they announced a new multi-billion-dollar drainage canal that will help reduce the risk of flooding from rainfall upcountry. Which, since you’ve been paying attention, you know would have not helped with the current flooding one bit.
As the water continues to recede and the fish return from the streets to their natural habitats, the land begins to dry out and life on that land returns to normal. Everyone in Bangkok is looking forward to November when the rains will be nothing but a distant memory.
But first there’s October. The second rainiest month.
