Tuesday, September 13, 2011

The world's biggest morning glory

"The grass is one of our sensors" said Andrijanto, one of the managers of Jatiluhur dam. It is the third in a series of large dams storing part of the water supply of Jakarta. Nearby a herd of goats walked on the sloped face of the dam, far enough away that we could not hear the bells around their necks. Apparently, when the dam face starts leaking, the grass turns green and this is a low cost way of monitoring it. Maybe the goats are a low cost way of maintaining the sensor too.

Goats on the job, left
Jatiluhur also has the largest “morning glory” spillway in the world. It is shaped like a squat vuvuzela so water can flow over the top of it and down into the center.  Three other dams claim to have the largest such spillway (Whiskeytown Lake, Ladybower Reservoir and Monticello Dam, each around 25 meters/80 feet diameter) but Jatiluhur is wider than all of them combined (90 meters/290 feet). 

Walkway to the morning glory
 When asked if he’s been to the bottom of the spillway Andrijanto answers “Of course, of course!” Apparently willingness to go in the spillway is one of the conditions of working there (but not necessarily part of the job interview). Naturally, there have been times that he went to the bottom and co-workers joked that the crane to bring him back up was broken. I do think the original crane attached to the dam was broken, however.
The view down into the spillway. Note metal ladders at top of photo for scale.
The overhead view of the spillway from space on google maps
Group photo of water managers (in blue uniforms, Andrijanto is 3rd from the left) and researchers from Pusair. 

A few times during the tour of the grounds, Andrijanto touched on a theme of “The most important thing in water management is discipline.” Discipline to do routine maintenance. Discipline to stick to the plan, even during crisis. Discipline to have a plan. “Obey the rules, have discipline”.

It is something of a contradiction because every couple minutes he was eager to demonstrate some innovative feature they had implemented. There is only one Jatiluhur dam and it probably does not have a user guide (or rather the manual is likely 10 binders large... turn to page 2,968 for “what to do if goat falls in spillway”). They need practical creative solutions to one-of-a-kind problems. It seemed like when they ran out of ideas they asked the sage engineer who has worked there longer than I have been alive (next year he gets his 50-year pin). 

As we walked down the tunnel inside the dam to the base of the spillway (photos not allowed), the air gets hot and dank like the bottom of a mine. The air conditioner was not working that day. The tunnel openned to a flourescent lit cavern with turbines and control panels. Everything was cement and metal so there is nowhere for the sound to go as the turbines whir away. Some of the large machines were being field dressed, every part laid out orderly on a blanket.

Into the tunnel

It sounds like Andrijanto has thought about the dam day and night for the 10 years he has worked there. He is paid to worry... worry effectively. There is no room for self-deception. My impression is that his biggest fear is that some day something will go wrong with the dam and a pitchfork and torch-yielding angry mob will come and carry him away.

Problems do happen. Just two weeks ago a small spillway at Buaran Dam failed on one of the delivery canals far downstream. A bank gave away, causing water to flow back into Buaran River, cutting off water supply to the Pejompongan water treatment plant in Central Jakarta. Nearly 1 million customers were affected for days. They say it was a combination of a “natural disaster” and a lack of maintenance.

Andrijanto’s impression of forecasts? Before the largest flood in recent history, the climate forecasters were saying it was going to be dry, so the operators tried not to draw the reservoir down too much. In essence, they were told to zig and the climate zagged. Maybe this was climate change they thought.

What is a water manager to do in that situation? “We cannot reject the decision of the forecasting agency, they have the authority to make the forecasts” It is not the water manager’s place to second guess the forecasters. The forecasters are experts, that is their job. “They have the equipment to make the forecasts, not us”. Of course, like the US and Australia, the forecasters get feedback and suggestions from the water managers, such has how there might have been recent errors.

At this point, Andrijanto turned the tables and asked “Do you think that we have to review our models for climate forecasting in the future?” In essence, what do I think of climate change? Remember, the recurring theme to this point was to make a plan and stick to the plan... but make a new plan if it is clear that something else is needed. Do they need a new plan?

First, I do not know enough of the technical details about Indonesia’s systems to make any conclusions. Also, changes in predictability 1-3 months ahead is a subtly different issue than if the climate itself is trending or becoming more variable. But I said that, at least overseas, it is clear that the climate is changing and it is going to change in the future. Of course the models are wrong and are not going to work as well in the future. How things will change though is uncertain, so I cannot suggest a better plan than what they already have. It is like “the road is due for a curve, we just do not know if they should start turning left or right... Be prepared for a turn however”. Spoken like a true academic I suppose!

Control building with Mr Heru
We asked the senior engineer if he had any reflections after 49 years? He said that building the dam 1 meter higher would make it capable of handling the Probable Maximum Flood (basically the largest conceivable flood, the total worst case scenario). In the meantime, I suppose everyone has to expect the unexpected and hope that the angry mobs and goats keep at bay.

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