Air and Water Data

Raleighvallen Rainforest School

Air and Water Data

Omar reading river temperature

Daily Measurements of air and water at Foengoe Island

LAND BASED MEASUREMENTS

Everyday using a maximum-minimum thermometer we record the highest and the lowest temperature for the previous 24 hours. We make our measurements in degrees Centigrade but we also convert them to Fahrenheit because those of us from North America understand that scale better. As you can see it was a little cooler in January and early February than in March. But the nightime temperatures have not changed much. We were not here at Christmas time so there is no data for a three week period then.

We use a rain gauge to collect water and record it once a day. Average temperature is the average of the maximum and minimum daily temperature. KWH is a measure of the amount of solar energy that reached our solar panels. It gives us a measure of sunshine for the day. If there is a lot of rainfall in the daytime then there is less sunshine. Sometimes most of the rain comes at night so there is not a decrease in sunshine. The long rainy season began about April 1.

Our friend Emily helping us

RIVER MEASUREMENTS

The river level changes every day. It has come up 18 feet since we arrived at the end of thedry season. On the graph below, you can see the results of the short rainy season in January-February and the beginning of the long rainy season in April. Rain falls far to the south of us at the headwaters of the river, causing the river to rise sometimes one meter in a day.

Coppename River at Foengoe Island, 2005

Our measurements of the river show a relationship between water level and its clarity and temperature. We measure the water level everyday with a permanent 7-meter stick that we made and placed in the sandy river bottom. It is a tall, slender tree trunk; we removed the bark every ten centimeters (cm) and painted a green line. Every meter (m) we made a wider orange mark. We record the water level every morning.

Chuck and Michael setting the pole

Water clarity (or its opposite turbidity) is measured with a Secchi disk. We made ours from wood and painted it white. Very recently we got a commercial plastic one from the US Geological Survey. They both work the same. We lower the disk into the water until we can't see it. We try raising and lowering so that we can get the depth where it just disappears. We record that in tenths of a meter. The rope is marked every 10cm. When the water is low, it is also flowing less quickly. Their is less runoff from the land and we can see deeper into the water. It is never clear as there are always a lot of tannins from land plants. They make the water appear brown.

We measure temperature with a thermometer on a line. We try to measure surface and 2m temperatures but sometimes the current flows too strongly. The two measurements are almost always the same except when the water was very low at the end of the dry season. Then the surface water was 2 degrees Centigrade (C) warmer than the deeper water. When the days are sunny and the shallow water flows slowly, it warms up. It is like getting in a hot tub at the end of the day when the water is warmer than the air. As you can see above when the water level rises the tempaerature falls--but not much this is the tropics.

Pascal measuring turbidity with a Secchi disk

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In the middle of the Central Suriname Nature Reserve, Amazonia, South America