permaculture

["Lawrence F. London, Jr." <venaurafarm@bellsouth.net>]

> http://www.smithsonianmag.com/history-archaeology/Farming-Like-the-Incas.html
> The Incas were masters of their harsh climate, archaeologists are
> finding, and the ancient civilization has a lot to teach us today
> By Cynthia Graber
> Smithsonian.com, September 07, 2011,
>
> Inspired by recent archaeological research, the people in the Cuzco
> region of Peru are rebuilding terraces and irrigation systems and
> reclaiming traditional crops and methods of planting.

A Marvel of Inca Engineering
http://www.pbs.org/wgbh/nova/ancient/wright-inca-engineering.html

A Marvel of Inca Engineering

    Posted 01.01.10
    NOVA

The ancient Inca wonder of Machu Picchu, perched 8,000 feet above sea 
level on a ridge in the Peruvian Andes, was a royal estate for the 
legendary warrior Pachacuti, who was largely responsible for building 
the Inca Empire in the 15th century. Like other massive stone 
constructions of this formidable emperor, it was built with eternity in 
mind. But how did Inca builders ensure that Machu Picchu would survive 
in its precarious mountaintop setting? Ken Wright, a civil engineer who 
has been studying the site since the mid-1990s, explains in this interview.
An aerial shot of Machu Picchu.

While impressive today, Machu Picchu would have been an even greater 
site to behold in the late 1400s, with gleaming white granite walls 
topped by golden-colored thatched roofs. Enlarge Photo credit: © Jarno 
Gonzalez Zarraonandia/iStockphoto.com
A royal challenge
NOVA: What was your first impression of Machu Picchu?

Ken Wright: When I arrived in 1994, my first visit ever, I was blown 
away by the view of Machu Picchu itself and also by the surrounding 
territory. The first question in my mind was, why would they ever take 
on a site this difficult? Engineering wise, it would seem almost 
impossible to handle.

The first day, I was not looking at engineering evidence, I was being 
awed by the site, just like every other tourist. The second or third 
day, I began looking at the Inca spring and the canal, a canal that led 
for 2,500 feet to Fountain Number One and all the way down to Number 16. 
I saw not just a water-carriage system but a well-engineered system. A 
lot of thought had gone into it. That was when I first realized that 
this was an engineering marvel.
Why would the Inca build on such a difficult site?

The more I became familiar with the site and looked at the mountains and 
the rivers surrounding it, I realized why. The Huayna Picchu mountain on 
the north, Machu Picchu mountain on the south, Mount Yanantin, the 
triangular peak Putucusi—all of these are holy peaks. We know they are 
because when we're with the Quechua Indians, the people who are the 
descendants of the Inca, they pray to [these mountains], so the site is 
a natural. It couldn't have been better as a royal estate for Emperor 
Pachacuti.
An actor portays the emperor-warrior Pachacuti, a still from

An actor portrays the imposing emperor-warrior Pachacuti in "Ghosts of 
Machu Picchu." Enlarge Photo credit: © Ricardo Preve/National Geographic 
Television
How did they know that the mountain spring would provide adequate fresh 
water?

What the Inca likely did, upon arriving at the site and before deciding 
that they were going to build there and before cutting down all the 
trees, they would have studied the spring and made some measurements, so 
they'd have an idea of how much it would flow and how much it would vary 
during the year. We know they did that because the evidence tells us 
that the canal was just the right size for the spring yield, and the 
fountains are just the right size for the canal.

How long they spent studying the site, we don't know. But it couldn't 
have been a long, long time because all of Machu Picchu was built in 
roughly 90 years [A.D. 1450 to 1540]. They couldn't have spent a decade 
studying the water supply. I would think a year or two.
If you had been an Inca planner, overseeing the building of the estate, 
what would have been your greatest challenge?

The biggest problem would be landslides, unstable earth, and for that 
reason I would have my civil engineers focus on being good stewards of 
the soil. Stabilize the slopes with the appropriate terraces, and plenty 
of them. The other thing I would do is spend a lot of time and effort on 
foundations and site preparation, because I knew I was building for the 
ages. And the Inca engineers did spend about 50 percent, maybe 60 
percent of their overall effort underground—doing foundations, site 
preparation—to make sure that Machu Picchu would last forever.
A stable foundation
How did you get a sense of all the underground foundation work they did?

We had an excavation done in the Plaza, a very important part of Machu 
Picchu that separates the eastern urban sector from the western urban 
sector. It went down probably nine feet. In that nine feet, we found 
about three feet of topsoil, rich topsoil. Under that was a sandy, 
gravelly-type soil, and then we came across an underground, subsurface 
drainage system made out of waste rock from all of the stones that 
they'd been cutting for years and years and years.

This rock turned out to be white because it was white granite 
originally, before turning color with age. So while we look at Machu 
Picchu today and see gray buildings, when it was built, it was white 
granite. At any rate, the white granite told us a lot about their 
engineering ingenuity and their desire to provide good drainage for 
Machu Picchu, because without good drainage, there would be no Machu 
Picchu existing today.
A diagram of a Machu Picchu drainage system.

Wright's excavation revealed a vast underground drainage system with 
layers of topsoil, sandy gravel, and granite waste rock. Enlarge Photo 
credit: © 2009 NGHT, Inc. and WGBH Educational Foundation
There was a surprise for you at the bottom of the excavation, right?

Yes. At the very bottom of the excavation was a golden bracelet—the only 
gold found at Machu Picchu—and we are very pleased to have that. It's in 
the Cusco Regional History Museum today.
Why was good drainage essential? How much rain does the area get?

About 76 inches per year, and it mostly falls during the wettest seven 
months or so. That's a lot of water, roughly two and a half times as 
much as the city of Chicago gets.

    "The beautiful curves are a masterpiece of environmental and 
aesthetic design."

What role do the many terraces play in this system?

The terraces, the 700 or so terraces, have a high permeability, so the 
water goes down underground to be carried safely away. Terraces at Machu 
Picchu are fundamental to its longevity. Without terraces, the mountain 
would have slid terribly, so we see them primarily as the means for soil 
stabilization and support of buildings or trails. But they also provide 
agricultural area.
Terraces fortified by granite on the mountainside at Machu Picchu

Roughly 700 terraces carved into the mountain and fortified by granite 
walls help keep Machu Picchu stable. Enlarge Photo credit: © Ricardo 
Preve/National Geographic Television
In the urban areas, where the residents lived, did the Inca use anything 
like our modern sewer drains?

Yes. In the urban areas, you would find lots of thatched roofs. A 
thatched roof has a lot of run-off. It's almost like a parking lot, so 
they had to deal with the run-off, and that was handled by a 
well-planned urban drainage system.

Overall, we've found some 130 drainage holes that were planned during 
the initial construction of the walls, not put in as afterthoughts. The 
Inca were better urban drainage engineers than we are at the present 
time, because they planned ahead.
So you were impressed?

My reaction was one of admiration, one of awe, because these people did 
not have a written language, they did not have iron or steel, they did 
not use the wheel, and yet they were developing drainage systems that 
were good. And we know they were good because Machu Picchu has lasted 
for some 500 years.
How does the stability of land at Machu Picchu compare with that on 
surrounding peaks?

You can look around at surrounding mountainsides and see landslides that 
have happened in the past 10 years or so. But at Machu Picchu, it's been 
quite stable. Now, that doesn't mean that the Inca were perfect. When we 
look carefully, we find some buildings have settled, like the Principal 
Temple, and we find clues that the Inca had a landslide that they were 
in the process of curing. So there are a few places where the magic aura 
of the Inca did not mean that they were perfect.
Temple of the Sun sacred rock bathed in sunlight.

Another Inca marvel: On the morning of the summer solstice, light pours 
into a window of the Temple of the Sun to illuminate a sacred rock. 
Enlarge Photo credit: © Ricardo Preve/National Geographic Television
Did the quality of the Inca stonework also play a role in Machu Picchu's 
longevity?

Certainly. The Inca buildings have endured because of the good 
foundations, the slope, the interconnected stones, the tight joints. 
They built for the ages.
The stonework is beautiful, too.

It is. Hiram Bingham [the American explorer who found the site in 1911] 
called the Sun Temple's Inca wall the most beautiful in South America 
because of its exceptional design, the way the stone is shaped and 
carved. It's a masterpiece, and it's beautiful, and it has withstood 
earthquakes now for 500 years. But from my standpoint as a civil 
engineer, my greatest admiration is for the water system and the 
fountains, because they are so out of this world.
Sacred waters
How did the Inca plan the layout of the estate, particularly given that 
they had no written language?

Machu Picchu is a planned estate. It certainly was not built 
haphazardly. But we know that the Inca had no writing, so they may have 
drawn plans up with clay models. We don't know that, but we do know that 
it was planned because the evidence is there. Everything is orderly; it 
fits.

The Inca spring, in many ways, controlled the layout of Machu Picchu. 
The location of the spring was fixed, and the Inca engineers figured out 
the slope of the canal and set it at an average of about three percent, 
and the length was fixed at about 2,500 feet. These things were 
determined by nature and by hydraulics.
Machu Picchu stone canal and fountain system

The canal and fountain system, designed to provide a steady flow of 
fresh water, shows remarkable planning and foresight. Enlarge Photo 
credit: © Ricardo Preve/National Geographic Television
So did that help determine, for instance, where the Emperor's residence 
was sited?

Yes. Obviously, the Emperor should have first use of the water, the 
cleanest water [from Fountain One]. So that's where they built the 
residence, and they also built the Temple of the Sun there, and Wayrona 
[a three-sided building], and Fountain Number Three, which is a sacred 
fountain.

    "Every time we visit Machu Picchu and study some aspect of it, we 
are more amazed than before."

How do we know that water had a sacred nature for the Inca?

They went to special care to provide the sight and sound of flowing 
water, or falling water. And that included the sight and sound of water 
from the Urubamba River 1,600 feet below. The roar at Fountain Number 
Three and the Wayrona was loud, and delightful.

Also, just outside the walls of Machu Picchu is an overhanging rock, a 
very important rock. This overhanging rock catches the sound from the 
Urubamba River 1,600 feet down and amplifies it, so when you're in this 
little area, the roar is good. So we could tell from the evidence of the 
layout that water certainly had a sacred aspect in their religion.
Do you see a reverence for nature in other ways at the site?

Yes. Walking through the main gate, the only formal gate into Machu 
Picchu, you find that the doorway frames perfectly the wonderful peak of 
Huayna Picchu. The ancient windows have special views, either of the 
Urubamba River below or of a mountain peak, and then when we look at the 
terraces near the guardhouse, we realize that these terraces weren't 
built just for utilitarian soil stewardship purposes. The beautiful 
curves are a masterpiece of environmental and aesthetic design.
Machu Picchu residential complex surrounded by green mountains.

The breathtaking view looking down toward the residential complex 
Enlarge Photo credit: © 2009 NGHT, Inc. and WGBH Educational Foundation
Keeping clean
How much water could the canal and fountain system handle?

All of the fountains, all the way down to 16, were established to handle 
about 25 gallons per minute maximum. In the event that run-off water 
came into the canal during heavy rainfall, the Inca engineers provided 
two safety valves, one in the middle of the agricultural zone—it would 
discharge out onto the agricultural slope and just infiltrate into the 
ground—and another at the main drain. So what we saw was a balanced 
system all the way from the spring to the main drain.
And do we know that the water was kept clean? What do we know about Inca 
hygiene?

Well, Inca hygiene, we know little about it except the evidence that 
they left in the field. And we were amazed that the water supply canal 
was built in such a way that it would be pretty well isolated from 
drainage holes and from potential pollution. So it was laid out in such 
a way as to provide for maintaining pure water.
What about sewage?

Well, all we can say is that these people were agriculturally oriented. 
The power of the Inca Empire lay in its ability to produce food, food 
surpluses. But the [Emperor's] residence, which is nearby Fountain 
Number One, has a room in the back that's considered to be the bathroom 
area. The only house sanitary drain that we've found coming out of any 
building in Machu Picchu came out of that room, and it didn't go to any 
place where it could possibly contaminate. So we concluded that these 
people somehow had a sense of hygiene and pure water, long before 
Westerners did, for instance, in the city of London.
Another thing that impressed you, I imagine.

We've been doing this for roughly 15 years now, and every time we visit 
Machu Picchu and study some aspect of it, we are more amazed than 
before. The whole system of Machu Picchu is a marvel—not just the water 
system or the most beautiful wall—but how everything fits together, 
ranging from the foundations, which would be geo-technical engineering, 
to site layout, which would be city planning, to trails that deliver 
people from one location to another without interfering with someone's 
privacy, to the huge plaza which provided the space for celebrations.

When you look at Machu Picchu as a whole, complete with the temples and 
the solar observatories, you realize that it is a site that's well 
designed, well balanced, and somewhat of an engineering marvel.
Ken Wright

Ken Wright, a hydrologist and civil engineer, has been studying the 
waterworks and other engineering achievements of Machu Picchu since 
1994. Enlarge Photo credit: © 2009 NGHT, Inc. and WGBH Educational 
Foundation

Interview of Ken Wright conducted September 15, 2009 by John Bredar, 
senior executive producer for National Geographic Television, and edited 
by Susan K. Lewis, senior editor of NOVA Online