Thursday, April 26, 2012

Iran’s Largest Earthen Dam (Gotvand Dam)

The saying in the US goes: “Try as you might, there are two things you cannot avoid in life…death and taxes”.

In Iran, it’s “death and drought”. You can get out of taxes if you really want to.

Today we go inside one of Iran’s attempts to get out of drought. This post may look long but it’s mostly pictures.
Dry mountain landscapes in Southwest Iran

About 30% of the world but 90% of Iran is arid or semi-arid, meaning that rain wouldn't provide enough water to grow food. Ahwaz’s average annual rainfall is about 250 mm (9 in), about the same as El Paso, Texas. Some years have been drier than normal recently and with increased demand for water, the stresses on the system are greater than ever. Add in revenues from oil, a desire for energy independence, and strong government support for technology, and it should be no surprise that Iran has one of the most active dam-building programs in the world.
Dam Tom
Our side visit to one of the lower dams near Ahwaz

Depending on the landscape, many smaller dams can be more cost effective than mega-projects, but Iran also has its share of superlatives (e.g. biggest this, tallest that). One of those is Upper Gotvand Dam (Gotvand-olya, also Gotwan), the tallest (182 meter, 600 feet) earth-fill dam in Iran. “Earth-fill” means the dam is a long squat mound of dirt and rocks, which gets its strength from being large and heavy. This is as opposed to concrete dams which are thinner and shaped more a thumbnail; the water pushes concrete dams from behind and this wedges the edges deeper into the canyon walls. Hoover dam is a concrete dam, for example.

Here’s the face of Gotvand dam. The photos can’t take in the giant scale of it all. The distant specks at the end of the middle white line are dumptrucks. The green symbol is the national emblem of Iran, a stylized version of the script for Allah (God).

Same view as above, slightly panned to the right.

We asked Eisa Bozorgzadeh (Technical and Research Deputy of the Iran Water and Power Resources Development Company, IWPCO) if we could see the site. He was one of the organizers of the recent Hydropower Conference in Tehran.

Eisa arranged a tour on, around and inside the dam; we were picked up by a company car and escorted by one of the chief engineers and a chauffeur. It was the same service (and vehicle) Ahmadinejad had during his official visit at the dam’s christening. When I asked the driver what the President of Iran was like in person, he replied that “I am just driver of car, I cannot speak”. I took it to mean either, drivers can’t talk to dignitaries, or they’re not allowed to gossip about other dignitaries.

Visit to the main office of the dam (Kitty, me and the engineer, Mr Naderan)

Earlier that week we had visited the power company’s head office in Tehran. In the lobby of that building were a host of scale models and wall-sized maps.

A scale model of power generating turbines

So it was strange then going to see the real thing:

Inside the actual partly-constructed power-house

Our day at Gotvand started with the screening of a promotional video about the dam, why and how it was constructed and so on. The soundtrack of the video reminded me of Lord of the Rings, ranging from tranquil woodwinds to thunderous battle scenes.

We were treated to a 3-D computer model fly-through of the dam.


The spinning turbine. Think MCP from Tron.

We were also lead through the dam’s schematics…
Side-view of the dam. For how tall it is, it’s many times as thick.

The schematic showed a complex network of tunnels through the mountainside. This is looking down from the top.

Then we drove all over the site, a good portion of which was still under construction…

Downstream of the dam looking upstream. The building with the windows is where power is generated. The dam is in the background, left.

The view from the top of the dam looking downstream.

From the top of the dam looking upstream (the vertical black slots are where water goes into the tunnels)

Same view, looking left. Again, it is impossible to take in the scale and size of things. Those dots in the water are boats, patrolling the lake as it fills for the first time.

The wind at the top of the dam felt like it was going to knock us down.

The spillway partially completed. Note the lettering on the side of the hill. Spillways are like the overflow drains on a bathtub. If the level gets too high, water can be released quickly and safely, but without generating power.  

The view down into the spillways. Eventually tall metal gates will be put in these slots to hold back the flow, or be raised on demand. I can't even see anything in this view to give an idea of the human scale. 

Looking downstream across the spillways. 

In that mass of rebar in the foreground of the previous picture was a worker free-climbing (without a harness as far as I could tell).

The motto “We want. We can.” Note the painted over C between “We” and “Can”. It must have been a rough day on the job site when they discovered a typo on the mountain.

The dam itself is full of sensors to check if it is leaking or cracking or moving in any way.

Next we drove inside one of the dam’s many tunnels.

A robotic drilling machine, I think for putting in reinforcements in the dam walls. Human to left for scale.

In the heart of the outlet tunnels were a variety of pumps and control panels.

And then there was this… Water is roaring through this tunnel on the way to the outlet. It creates wind and noise unlike anything I had witnessed before. We were warned to take off glasses and remove anything loose from our pockets. When this metal portal was pulled open, the roar was like when the cabin of an airplane loses pressure mid-flight and everything is sucked out towards the hole. We thought we were going to lose our fillings.

Here’s a video. Turn on the audio for full effect.

Strong winds inside the dam’s tunnels

I’m surprised Kitty didn’t have her smile blown off. Happily it stayed with us for a while.

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