The Native Iowan

I remember vividly moving from rural Iowa, heading off to the new world of being a Peace Corps Volunteer. Moving from the solid, flat old-country to the steamy, rugged and dark islands of Melanesia.

I think I learned a lot about islands very quickly. Quickly for a flat-lander, that is. I learned that some beaches are golden sugary-fine coral sand, while others are black coarse volcanic sand. Some islands have surface water (rivers, stream, lakes), while other have no visible water sources.

I remembered Gilligan’s Island was a “desert-island”, so some of the stuff I learned made sense and some did not.

It took me a long time to figure out that wells in coastal areas would have “sweet-water” in the top layer of the well, and brackish or “sour-water” in the lower levels. The deeper you went the more brackish or sour the water became.

Now I am no scientist but I am an engineer. And a farmer! I think of myself as a quite astute “problem-solver”.

I remember the communal well at Siota PSS, on the Island of Small Nggela…

The school is still there:

Now, in the major scheme of things Small Nggela is a small island. But it is a “big” island when it comes to islands and it has a lot of surface water. Big rivers, small streams, plenty of water.

But the school is in a weather shadow. The eastern side of the island got the weather, was the “weather-coast” of this island. Siota, though wet by many standards, did not have running water in close proximity.

One very important lesson I learned at Siota was how to manage freshwater resources.

The school satisfied its freshwater needs through a combination of water catchment and wells. When it rained it rained! Tanks would overflow, everyone had water when the rains came. The “kink” here was that the area went through frequent dry spells. A dry spell could be anything from a few days to weeks.

The facts about water catchment are simple: 1mm of rain on a square meter of roof space equals 1 litre of water. A 10mx10m square roof thus produces 100 litres for every 1mm of rainfall. Even though it rains a lot, your storage is what counts. You need to store the water and storage capacity is limited to the size of the tank(s) you have. The more you can store the longer the dry spell you can endure.

It’s easy for a person to need/ use 100litres of water a day for cooking, cleaning, personal use. Siota had about 300 students and staff living on site. That puts Siota’s daily water needs were around the 30,000 litre per.

Siota had nowhere near 30k litres of water storage capacity.

Once the rain ceased people had to stop using their rain tanks gratuitously. Water caught and stored in the tanks was reserved for cooking/ drinking. The wells were used for bathing and laundry.

The well I used, the men’s well, was by the HeadMaster’s house at the east side of the school. It was over 100meters from the sea-side. Of simple construction, three, 2meter, concrete culverts had been dug into the ground. The bottom was open, sandy. A nice concrete apron had been laid around the well. We used a plastic bucket with a bit of rope to draw water. You’d toss the bucket in the well, shake n pull the rope until the bucket started filling, then haul out your bath or laundry water. I learned quickly that the deeper you let your bucket sink the more brackish the water. It was a trick to be able to get a full bucket of fresh water.

I found that in times when the well was “high” there was a nice thick layer of freshwater. You did not have to worry about the bucket sinking too deep and filling up with sourwater.

I found that as the water level in the well dropped the freshwater levels decreased, but the sourwater levels remained fairly constant.

This puzzled me. I slowly worked it out…

Different from what I thought first-off, seawater and underground water aren’t isolated systems. The well isn’t filled up by rain water, like a rain gauge. The freshwater in the well is part of the freshwater aquifer. Below the freshwater aquifer was the seawater. The seawater and the freshwater are actually in the same well at the same time. The freshwater floated on top the saltwater.

Rocks, soil, sand, “the ground” is more or less porous. Water can move through (albeit slowly) so the rains supply the overall aquifer. Freshwater, being lighter than saltwater, floats on top of the saltwater. When the freshwater aquifer or “lens” is well supplied, the wells were fuller and the freshwater layer in the well was thicker. As the dry spells lasted the freshwater lens for the entire island shrunk as was evidenced in the well.

I moved from Siota to Taro Island in Choiseul Bay. Taro is a much, much smaller island. Its wells were shallower and more prone to brackishness. We relied on our water tanks heavily and were in strict control of how much freshwater was used.

Much later in life I spent time bouncing around the Vona Vona lagoon. One island I canoed past regularly, on my way to Zipolo Habu, had quite a big population, numerous houses, possibly upwards to a couple hundred people, men women and kids.

It was a “small” island, maybe 300meters long and 50 meters wide. It had large trees and one could see gardens as you canoed past.

Then one trip I saw that everyone had moved away. I didn’t travel that area often so I don’t think this all happened quickly, within 12 months or so the island went from being pretty well populated to being depopulated. I noticed the greenery on the island was gone. Except for the magroves…