Fishing in Barra...

"We will be on the beach on the right side of the pier" said Emiel when he left with Ivan to try and catch some fish. Michel and I were at the student's house in Barra where life in the evening continues at a different pace than during the day. We had just delivered some tubes for use with the inverted Hooghoudt auger hole method, when they walked out with their fishing rods. We decided to take a look at the beach at sunset, which we do not do often enough.

Ivan and Emiel fishing on the Beach in Barra

It proved to be not as pleasant as we thought it would be. Everybody on the beach was trying to fend off a lot of small, itchy flies. Ivan caught a Robalo and we left. Don't know what happened to Emiel, Ivan and the flies...

More geophysics in the Presa Velha catchment

With the waterlevel measurements in the wells in their area all done yesterday, the Presa Velha group of Donovan, Abdukadir (Abdi), Lucas, Sanne and Joel decided that they would also do geophysics today, and placing some soundings in the forests in particular to find the depth of the Cretaceous clays.

Presa Velha: geophysics a gogo...

Abdi asked if we had any views of this blog from Africa yet, and I had to disappoint him. So this is for all you people in Africa - Abdi does think of you and sends a big smile to you in the picture below!

Abdi says hello to the world, and Africa in particular!

Geophysics, beach hydrology and tablets

With hydrochemistry out of the way, it was time to start the next phase. This is more focussed on hydrogeology. When you want to grow a cabbage for your Caldo Verde soup, you need some water and good soil. Us geologists call these good soils "Quaternary sands", as these are recent deposits of old rivers, beaches and dunes that the local farmers like very much. Below this stuff is usually some less permeable layer (Cretaceous clay) with a low electric resistance, and the question is at what depth it is, because this determines how much water you can extract for irrigation.

If it is shallow, we could use an auger to get the answer, but sometimes using geophysics is also a nice way to find out. Our Mesas group reached the same conclusion and reserved the vertical electrical sounding (VES) equipment for a morning session between aggressive flies in their area. Although everybody used this equipment in the Twente field course, it is always difficult at first to find out how to connect all wires. In the picture shown below it is clear that everybody tries different strategies to come up with the correct answers.

How to connect VES wires? Would drinking water help, or discussing the question in Spanish while looking at a bunch of wires, or is practicing yoga a better strategy?

Terrameter Valentina telling everybody to get their hands of the electrodes so that she can apply 2000 V to Mother Earth

With the answer found, the 2000 V power is switched on and a resistance measurement made, plotted on paper, electrode distance increased and measurements repeated. We also have a Geonics EM34 that uses a different method to achieve the same and it was compared to the VES.

EM34 measurement looking for Cretaceous clays below Quaternary sand

These measurements were done by all groups and a tablet computer, given to each group at the strat of the field course, was used to enter data, display the geologic map, find the piezometers that were installed in earlier field courses here, and so on. This works surprisingly well and it also helps us to find our way around.

Meanwhile, on the beach of Costa Nova, BSc students Evy and Leonie were still measuring water salinity on a mudflat. Now they used some real kind of industrial art, called a spiral auger (the Van Harlingen auger after its designer), to sample groundwater at different depths. The handle got stuck, was repaired, but now the thing starts at 3 m height, so they have to use the box to reach its top.

Leonie and Evy sampling groundwater with the Van harlingen auger.

The final week of our course has started today and it is time to determine changes in groundwater storage by measuring the water levels in the large diameter wells, as was done in the beginning. Below is the Sao Romao group group doing their thing as a well-oiled machine.

Sao Romao Group entering well data in their tablet computer.

More posts will follow soon...

Hydrochemistry and piezometers

"Ughh, I swallowed a mosquito" was what I heard when we were installing a piezometer in the afternoon today. This was all the more surprising because it came from a student who is known for cooking exquisite meals.

In the morning, Michel and I had gone to the students in Barra to pick up the water samples that they had collected in their catchments over the past week. There were nearly a hundred samples and they all had to be acidified before we could ship them to the laboratory in the Netherlands where they are to be analyzed before our return.

Presa Velha group sampling Fonte Juncal

With this out of the way we went to Montouro for a coffee and a "Mesas catchment" group meeting. As Miguel finally took a day off we met up with the remaining members and discussed what they were up to. They wanted to know how deep the Cretaceous clay was below the Quaternary sands near the village of Covoes, after seeing a geophysics VES that told them that it should be at about 2 m depth. Installing a piezometer also allows you to know the waterlevel in the area and the quality so we took our cars and went for a spin with the pulse auger set.

Ilaria making a piezometer hole in the ground, Valentina, afraid to get sucked in...

This was easier said then done as there proved to be much gravel in the Q-sands, which made it difficult to get through, without bringing in the full weight of Waterloo and the endurance of Groen.

Michel going through gravel layer

However, it was done somehow, we reached the Cretaceous clay at 3 m. Piezometer VU48 was made, water level sensor prepared and everything noted down in field book and in the Ipad.Group very happy...

Happy Mesas group after piezometer installation

Somewhat earlier, the Sao Romao group had also installed the VU47 and VU46 piezometers in their area under supervision and mental coaching of Ilja and Michel.

Sao Romao group looking for groundwater in a grey tube...

Things are thus going well!!! Except for the river hydrology perhaps, Tabuaco and Mesas streams are drying out, leaving the discharge people without anything to measure.

Miguel and his Mesas stream, only a few days earlier when there was discharge...

So they are the only ones here who would enjoy a good rainstorm.

Tiny island studies, piezometers, sapflow and BBQs...

Let's recapitulate the past week, we have been a bit slack in putting up new pictures and stories, but we were all busy.

BBQ

Shrimp, fish, meat, potatoes and veggie burgers all fit nicely on a BBQ. It is such a pleasure to have a device like that in your back garden and a very friendly landlord who puts up the lights for you. Portugal is a great country, never mind the crisis.

BBQ at Edificio Sao Gabriel

This is one of the things that I love about my job. The other one is the contacts with students. "I was waiting for you to tell me where and when to measure discharge in our area, but after some time I concluded that you were not going to tell me this. So we went out and did it ourselves" is what Abdi told me over a nice salad. That's exactly what we want and our students never disappoint us. Field courses are the best!!!

The island study

Leonie and Evy decided to spend the night on the tiny island in the Ria de Aveiro and do half-hourly measurements of waterlevels and electrical conductivity in water extracted from minifilters at different depths in the groundwater to see the changes over a full tidal cycle. So we bought a tent, a good flashlight and a warm pizza and off they were. I know, this sounds easy, but it was tough staying up all night after a full day of work. They made it through the night and a drowsy looking couple greeted us on the island the next morning, all ready to leave except that we still needed to do some measurements...

Leonie picking us up in early morning

Evy and Leonie having received yellow-ape medals of honour for their 24-hour continuous research shift on the island.

Vincent had to leave shortly after for a conference in Buzios, Brazil, but the we shall continue here, and later in the Netherlands to report about this.

Hydrochemical sampling and placing a piezometer

Meanwhile, in the Vagos area 17 other MSc students are still doing their thing. This was mostly taking water samples because these need send by courier for analysis in the laboratory in NL, before we all return in two weeks. You have seen the frantic activity of the Mesas group to take a river water sample in the previous entry and below is the sampling of groundwater by the Tabuaco group in a VU piezometer.

Sietse getting water from an old Nora well for comparison with piezometer water

Tabuaco group doing field chemical analysis of pH, alkalinity, EC and nitrate on groundwater

But it is not always that easy. Sure, this part of Portugal is littered with open wells that have groundwater in them, but how representative is that water when it has rainwater, fish, snakes, algae and sometimes rubbish or fertiliser bags floating in it. So sometimes you have to decide to take the extra effort get to the pristine groundwater from where it is hidden deep in the soil and do a piezometer installation.

This is exactly what the Presa Velha and Sao Romao groups concluded, after noticing that the piezometers placed by groups in the previous years had mysteriously dissappeared (we did found yellow tape and the piezometer cap). Transit arrives, auger is taken out, people walk around looking for the perfect piezometer installation point and the drilling begins.

Augering a hole for piezometer installation

Start with soil description and some sampling of the unsaturated part for chloride profile determination.

Soil sampling for chloride profile in the unsaturated zone, nice silvery mica sands!

When the hole is made, 4 m deep in this case, the piezometer is prepared with filter cloth around the screen and the thing is placed in the soil and the hole being backfilled. 

Preparing the piezometer

Finishing up installation as a team backfilling the hole.

Then the first muddy water is pumped out to clean the piezometer. Sampling will be done later in the week...

 

Sapflow

We also installed four sapflow sensors to measure tree water use. There was some discussion about whether to install eucalypt trees for a week and then four pine trees for the next week or to measure the flux in two pine trees and two eucalypt trees for two weeks. The ‘polder model’ also works in Portugal and so the students decided to first measure four eucalypt trees for four days, then two eucalypt trees and two pine trees for four days, and then finally measure water use in four pine trees for the last four days so that they can look at the differences in water use between the species and relate the water use patterns to the evaporation rates obtained from the weather station. 

Lex installing the first sapflow sensor, Robin making sure that he does it right, and Donavon holding the sensor.

Installing sapflow sensors is fun (or are they laughing at the high-tech drill?)

Do your water quality thing...

Everybody wants clean water, but there are lots of things in nature, or that we do, to make perfectly clean rainwater dirty while it travels through the landscape. Geology can be a factor, but also illegal dumping of waste or overuse of fertilizers. In our area we have all of this and now its up to us in this course to investigate water quality. We do this by applying the hydrochemistry theory we got from Pieter Stuyfzand and Boris van Breukelen earlier in the programme. To study the spatial variation in water quality we sample rainwater, riverwater and groundwater. The last water type through the sampling of fontes (public water points), noras and our own piezometers. Lots of measurement and notes needed!

Mesas river group preparing for river water sampling

Valentina analyzing Mesas river water for bicarbonate and Abdi, the pH specialist of the Presa Velha river group

The mesas group today cracked their alkalinity cartridge. The ultimate question is: how do you do this??? Fortunately, there are spares...

Sometimes freshwater is also threatened by the sea, and two BSc students earth Sciences from the VU University, Evy and Leonie, joined us this week to work on a tiny island in the Ria de Aveiro.Firts a workplan has to be developped and there's no better plavce to do this then the Coza Nova Bakery in Costa Nova.

Workplan with coffee in the early morning

The study involves travelling with our old shoe to the island in the Ria, followed by long sampling sessions on the beach using a spiral auger to extract water from different depths below the surface.

BSc students Earth Sciences Evy and Leonie (right) with their equipment

Travelling with a shoe-like, camouflaged, very ugly tiny boat is part of the hydrologic experience

The outboard engine may fail any time...

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Catchment installation pleasures

It has been a few days and as we were installing stuff, there was little time left for writing inspiring text to place on this blog. Apologies...

Lex gave me some pictures today from the Algarve field course. I think that you'll enjoy them.

How to handle a good Miocene outcrop

Emiel enjoying the Algarve excursion

Outdoor student exercise device in the Algarve

Guru Henk and his flock of dedicated hydrologists

Today is Sunday, trains are apparently on strike in PT and so we have a few extra hours. I should finish a bureaucratic report, but this is more fun to do and I am always in for delays... So here we go.

After the excursion on Tuesday, the students got a day to drive around in their area, meet some farmers, and stick some rain gauges in the soil to put up a rainfall measurement network.  On Wednesday me and Ilja went to the student's residence to discuss the workplan that they had to come up with. Some groups already had a detailed measurement plan, whereas others were a bit more vague. One of the nicest one was made by Chantal's Mesas group, a map with fancy colourful post-it papers showing their proposed sampling spots.

Map of the Mesas catchment with sampling well positions

Then off to the field for the installation of tipping-bucket rainfall gauges and water level sensors. First to the Rio Boco where we demonstrated how to install such a thing, and then with the individual groups to their measurement sites. We started with Tabuaco where the group with Lex (who talks too much according to Sietse) did their thing. Then on to the mesas stream where a logger was placed.

Programming the water level sensor logger

Now, this you don't get in the classroom lectures. Their river wasn't flowing so something had to be done, which was the cleaning of a lot of vegetation in their river channel. And that is hard and sweaty work. Here you see Ilaria assessing the situation.

Ilaria up to her knees in river veggies and who knows what else...

The spade was then used for things it wasn't designed to but in the end there was flow in their channel. In the meantime, the Sao Romao group had installed all their stuff and were dying of boredom with coffee, and delicacies in Cafe Veneluso in Montouro. Calling us every time to see if we were ready for them and being very much afraid that me and Ilja would opt for a lengthy lunch. So we drank a coffee and got these guys to install their logger in an inaccessible but very safe spot and got three of the guys cleaning their channel, which was also filled up with veggies.

Ivan and Leo working on the logger programming with Ilja.

 

Emiel and Robin installing a water level sensor in their cute little plastic trousers

Emiel, Robin and Leo in action with veggies, note who of the group is missing in this picture...?

 Yes, this guy stood laughing on the side.

Then on with the Presa Velha group to install theirs. We also took a look at a piezometer (how to pronounce this word is a study on its own) and a podsol, where Abdi Gure volunteered to be in the picture for the scale. Another day well spent.

Abdi with his spodosol...

Measuring the head in a piezometer in the Sao Romao catchment. Ilja pronounces this word very differently from Waterloo (and the other Dutch people) and now we are all confused. Fortunately the internet is there to help. If we could just remember this pronunciation......

On Friday we had to install the meteorology tower that gives us the evaporation rates.

Meteorology tower installation near Covao do Lobo

Waterloo adding the thermocouple to the tower and Lex swinging the psychrometer to determine the wet and dry bulb temperatures to calibrate the relative humidity sensor

A few water balance students admitted that they had been reluctant to join, and I guess they remained reluctant during the setup of the tower. However, this reluctance did dissappear completely when we started our traditional lunch in restaurante Sesta in Covao do Lobo (omelets, rabbits, pudding, wine, coffee, salad, sausage dish, etc.). I was too busy eating to take any pictures (other than this slightly blurry one), sorry about that, but it was excellent.

A toast at the end of the lunch on a successful field day

Then on to our favourite illegal garbage dump to say something about groundwater contamination and  and show a spodosol soil, now using Donovan, and a red spade as scale.

Spade as scale for Spodosol and Donovan as scale for spade.

Upon return, we stumbled on a corn field that was being irrigated and we talked to the farmer about his routine. Irrigation, only when needed and no clue about pump capacity or amount of water used. Everything just based on experience, this grandfather knew what he did.

Water balance team hidden behind irrigation sprinklers

Waterloo discussing the meaning of life with a small Portuguese farmer

On Saturday there was the soccer game NL vs. DK, which we, the Dutch, lost so let's not discuss this here and Sunday is still with us... Time for this terrible report writing, no excuses left...

Some of the students watching soccer at Marito's in Barra. The disappointment is already starting to show but was washed away with some extra beers.