Tuesday, June 11, 2013

Starting hydrology in Vagos

Life is not bad. For the supervisors, the day in Portugal begins with good coffee, and sometimes a pastel de nata.

Good morning Michel!
Students have to go to the Pizzeria to have internet, and when they get access they have something else to do then to write blogs. Today we had planned to install the sapflow equipment for measuring tree transpiration, whereas other groups planned to do geophysics. No such luck as these electronics do not like the steady drizzle that comes down. Of course, there are other options for a day like this, such as sampling public water holes (fontes) for water chemistry, or go and check if the discharge of your river goes up. My gut feeling says that this drizzle is no good for that, but will make you just wet and cold while you stand desperately watching the unchanging flow of river water. Me, I decided that it was time to work on this blog again.

So what have we done since last week? The day after the excursion, we decided to install the water level loggers in the streams as the weather forecast said it would rain.

Bob and Robbert installing the water level sensor in the Presa Velha stream
Then the groups went on to scout the area and install the rain gauges. When it finally did rain two days later, they sampled rainfall and did develop rating curves. For some groups this meant that they arrived at their Barra house only after ten in the evening when it got too dark to continue.

Other students tried to maximize their efficiency by driving as close as possible to their Presa Velha River discharge outlet in their rental car, that is not supposed to go off road. This is all very nice when the Cretaceous clay (C5 formation for insiders) is dry, but not when it starts raining and the clay decides to turn into a slippery surface, steering the driver (not Rosa!) into a ditch.

Digging was no good, so friendly farmers had to pull out a student's car while Rosa shouted out her joy in her best Portuguese
Unable to speak any Portuguese except "bom dia" and "sim", the group used their smartphones to show a proud owner of a tractor what they had done, so that this kind man could save them from staying overnight in the field.

Joris programming a 1990s VU made water level logger, the best you can get!
Piezometers have been invented by mankind to measure ground water level or quality. You can also do this in big wells, but then there may be all kind of disturbances, like vegetation, garbage or fish.

Looking into an old well to fish and a frog.
The advantage of wells, however, is that they are very hard to destroy and easy to find back. Not so our piezometer near Corticeira da Cima - of which only a damaged cap and some yellow tape was found back - or the notoriously bad-smelling VU4 piezometer near Tabuaco, which became buried under sand during logging and replanting of eucalypt forest. This one was only found by sheer luck when Louise randomly poked a stick into the soil to find the small blue tube. It took us hours to clean it from all the sand that had entered the smelly tube.

Thomas having a go at cleaning VU4 piezometer
Rather than rely on old, second-hand piezometers, the Mesas group decided to install their first brand-new one between four pinus trees.

Mesas group with their first piezometer still to be decapitated.
While installing a piezometer requires strength, perseverance and and sometimes brute force, the approach for a installing a meteorological tower requires delicacy and care not to damage the sensitive equipment. These are skills that Maartje, Patricia and Louise showed while attaching the instruments to their support arms and connecting them to the datalogger, whereas Corne (hates dish washing, likes smoking) and Seife did the more earthly jobs of augering away.

Patricia, Maartje and Louise working on the meteorology tower

Seife and Corne installing the tipping bucket rainfall recorder - kids play - just practice for the real thing...

After practicing on the rain gauge, Seife manages to put the casing into the soil without using his hands, while Patricia and Louise look on in admiration...
Then the water balance team finally came together to point the wind vane exactly to the North, using Louise up in the tower for adjusting the vane dirtection, a compass and a line of team members indicating the north to Louise.

Wind vane should point to the North.
We now use the Apple Ipad and the Campbell Scientific Loggerlink app to view and download the meteo data through a wireless connection, that's called progress (Thanks Ron)!

Finally, let's not forget our BSc students who were still busy on their tiny island, working away with the VU spiral auger to find and sample fresh water. For the connoisseurs, they found a shallow layer with an electrical conductivity of 825 microSiemens/cm, which is drinking water quality!

Marijn and Valerie in pursuit of fresh water
Again, this is the place to thank all the technical staff in the electronic and mechanical workshops and the water laboratory at the VU University, who develop, make, maintain and prepare for use all this specialised equipment for us. Frans, Ron, Hans, Niek, John, Tinko and all others, without you, we would be lost!

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