Watching the tide roll in

Saturday. Where else to go than to the island? After numerous vain attempts to locate an old piezometer with minifilters, Maarten decided that drilling a new one was our best option. While the students were getting soil samples, we drilled a 5 m hole on the beach. All went smooth until we discovered that our piezometer extensions that we had left behind the week before had mysteriously disappeared. That was a nasty surprise and Maarten went to the garage to get new ones. The nice surprise was that on the way he stopped to buy farturas and cherries. All in all, another great day spent on the island...

Watch this movie and see the tide roll in at 1080 times the actual speed.

More rain...

It rained a lot more last night and this morning. These poor guys planned to do geophysics but had to change their schedule...



In the afternoon the sky cleared so there was an opportunity to do install piezometers. Some people think it is hard, some people do it "with their fingers in their nose".



And this little movie shows another installation. The sand was a bit dry so it took a while. So long that the battery of the camera did not last...



And below some more impressions of the salt dilution discharge measurements and piezometer installations done by the hydrology students...













The field day ended when the piezometer was finally installed, and a groundwater level datalogger - kindly provided by WARECO Ingenieurs - was installed in the tube.

The first rainfall...

The Vagos area in Portugal is perfect for our field course hydrology. It has plenty of wells (groundwater access), a simple but sometimes hidden geology, many different land uses, several rivers that have water at this time of the year, many days with sunshine and always a few days of rainfall. In addition, the Portuguese people are very hospitable.

After a week of sunny weather, we now have a depression passing over Portugal that brings us rain. Rainfall causes changes in the river flow and this means that any schedule that the students have devised for measurements now has to be changed as they have to concentrate in getting the discharge rating curves to capture these changes in runoff caused by the storms and taking river water samples.

It rained last night about 26 mm. All students woke up this morning knowing what to do. Salt dilution discharge measurement method, propeller method, Nautilus method and the float method could all be practiced to get results. We joined the BARF group (Barry, Alexander, Rick and Frans) today. They went to Rua Sambal to measure discharge in the Presa Velha river. They started out with the salt dilution method, but as there was too much flow for their 10 l of salt water.

So they switched to the propeller method to check if this would give different results. As they did not have a rod, some improvisation was needed using a bamboo stick thtat was fortunately present at the site.

Then time to install a new piezometer at the meteorological tower to measure groundwater level changes! Again, the sucking soil did not make life easy.

Tired from all these exciting student activities, Vincent and I decided to visit the island for some fresh-salt water research. We took a rainfall sample and, amazing discovery, we found the spot where the brackish water returns to the surface after passing through the island, just as Vincent's groundwater model predicted!

Workaholic's weekend and progress meetings

For some people in Holland, the weekend starts on Thursday evening. But if you go with the flow in Portugal, there can be no such thing as a day off. Well, maybe on Sunday for some. So what would our students do?

Before continuing it is important to realize that they have been working hard since the first week of May in Twente. Upon their return in Amsterdam, they had a few days to wash their clothes and then they were off to Faro and Tavira to learn system thinking and well surveying. Due to this packed and efficient schedule, their energy levels had been depleted by the time they arrive in Aveiro. There was very little time, one day to be exact, to recover as the equipment needed to be deployed as soon as possible (see previous posts).

On top of that, work plans for the next few weeks had to be made and coordination between the groups was required to plan the use of the available equipment. That meant long evenings, often until midnight, before one could go to bed.

What would you do then during the weekend?

Here is what our students did this Saturday: They didn't stop working. They went back to the field to check if their equipment was properly working. The spent a few more hours to make sure precious dataloggers are properly protected. The staff in the meantime was packing the van in the garage as some of our students had even made bolder plans for Sunday: To install an 8m-well on the Ilha na Ria, the small island we are studying as a side-project.

Installing such a well should not be taken lightly. The weight of the augering equipment and the friction between the soil and the casing and the pebbles that get stuck require brute force to be applied sometimes. The goal of 8 was not reached but we made it to a respectable 7.2 m.



All thanks to great teamwork by Samuel and Caroline, although they did not really get off on the right "foot". To be exact: A little mishap occurred and Samuel's foot ended up in Caroline's eye but all that was soon forgotten. After almost 10 hours on the island we had ice creams in Costa Nova to celebrate the successful installation. These ice creams were so big that they did not fit on any photograph.

Then on Monday, it was time for progress meetings. Using time lapse photography, we made an impression of such a meeting. The movie below is played at 270 times the actual speed.



The plot of this movie is as follows: Staff members arrive right on time but the students are a bit late. Therefore, staff members chat with the owner of the bar and good friend Mario until the students arrive. Students get their coffees. Locals come and go to buy bread in the bar. Clouds pass by. Staff and students discuss previous activities and the work plan for the weeks ahead. In the end, the camera's battery is exhausted so the subsequent work meetings were not captured, but similar scenes would have been shot.



Today it rained and more rain is expected over the next few days. That means the hard work is not over yet...

How to spend your Sunday in a useful way...

Marcello from Coza Nova awaits us with splendid portuguese espresso coffee. It is Sunday, 8:15 h in the morning, and we've just picked up Samuel at his Barra Resort room. We are sitting on the terrace of Marcello's lunchroom looking over the Ria de Aveiro. Samuel had to wake up some of his fellow students, which they did not really appreciate, but we were not sure if they wanted to join in today's mission impossible. Caroline says she will join us a bit later and the rest of the students remain blissfully ignorant of our early morning activities.

We finish the coffee, a few pastel de natas and a kroket, and embark on our mission. It is a beautiful day and portuguese families flock to Barra and Costa Nova to enjoy a nice day at the beach. Our mission is different though. We will take our ugly boat and aim to install a piezometer on the small island in the Ria de Aveiro estuary, down to a depth of 8 m below the surface. Samuel is sure that this can easily be done.

While we see people arriving on the island for leisure, we are bailing sand out of an a PVC casing. At 5 m depth, gravel starts to interfere with our bailing making it hard to continue because the thing gets stuck in the casing all the time. An hour and a lot of sweat later, Samuel is ready to give up his 8 m depth goal...

The students fix minifilters on the piezometer to allow sampling of water at different depths for chemical analysis. Then we put the piezometer/minifilter system in the casing...

This is always the moment of truth: can we get the casing out because. You should realise that there's a lot of friction between the sand and 7 m of casing. This time things prove really hard. The upper casing breaks when we turn the contraption to get it out and we have to break our backs working in the sand. After several worried moments, we decide to use the broken part to try to lift the casing and that works!

We sample some water, see that it is a changing mixture of fresh and salt water with depth. We succeeded, but it has been a long day as we are back on shore only at 18:15 h and feel exhausted. I am really proud of all our hydrology students, their motivation and attitude is great and they hardly ever complain, even under difficult conditions. So we end our Sunday sitting at a terrace in our dirty clothes eating large, well deserved, icecreams. Life's not so bad...

Meteorology and the water balance

Part of our field course is to try to make a water balance of the catchment area. This basically means that we look at how much water gets into our area with rainfall, and balance this against the amounts of water leaving our area through evaporation, groundwater outflow and river outflow. The previous days our attention had been on installation of the rainfall and river discharge stations and now it was time to start with measurements of evaporation. This is done by setting up a micrometeorological station at a conveniently located site near Covao do Lobo where lunch is served first. The image above gives an impression of the site selection and the large role in this process of the mental coach.

When the team of students that will report on the water balance has found an appropriate location the meteorological instruments are mounted on a tower, the tower is erected and the logger is connected to the wire spaghetti and switched on. This usually takes a few hours and the whole contraption should then be running at sunset. This year, again, we lost our piezometer for measuring groundwater level changes as the field had been plowed. So we have to return here soon and install a new one...

Installation day, now it's getting serious

Student's all arrived safely at their "beach resort" in Praia de Barra, did their dirty laundry and went on to do some reconnaissance in the Vagos area where they have their five catchments. As their supervisors we went to the garage and prepared 5 instrument kits, for each group equipment including water level sensors, wading suit (too hot to use so remains in back of rental car all the time), boxes, hardware, tipping bucket rain gauges, chemistry kits, pH and EC meters, etc., etc. It was a hot day in that garage but we discovered that we had everything with us. Me "very happy" and compliments to Michel Groen and Frans Backer who again did a great job at the VU University getting everything together!!!

That is all behind us and today we had appointments with all five groups to meet in Montouro - at Café Veneluso, our favourite water hole in the study area - to distribute their instrument sets. There we had coffee, followed by a frantic exchange of stuff from our big van to the small rental cars.

Then went on to do the installation of the discharge measurement stations and (automatic) rainfall stations. You propably never did something crazy like this but it is good to know that this involves:

• Selecting a site (often wading through thorny bushes and garbage),


• hammering away on a steel pipe with mosquitos attacking you by some of the less fortunate groups that have a catchment that has not been studied before, or where staff gauges had dissapeared upon our return,




• Getting the dataloggers in place and programming them,




• Happy moments when finished...





• And of course some people prefer to do hydrochemistry while sitting on a dirt road near a dead, somewhat smelly snake.

It is late, tomorrow more about the meteorological tower installation and a copulent lunch at Sesta!