Gozo Underwater Cave Mapping

Today gave us an opportunity to obtain some long-awaited data from a cave in Gozo. At 7am Timmy drove us to Manoel Island Yacht Marina where we met our skipper, Paul. After carrying all of the equipment on the boat, Austin, Tyler, Prof. Clark, Paul and I departed and began our 1.5 hour voyage to Gozo. Apart from some heavy chop in the beginning of the trip, the day was beautiful and the ride presented some incredible views of Malta, Comino, and Gozo.

When we arrived we ran across some tour boats which continued to come to the cave throughout the day, but for the most part we enjoyed uninterrupted access to the cave. In addition to being the first time we had mapped a cave, today was the first time we had ever used the Smart Tether. The Smart Tether is an advanced piece of equipment that contains nodes every couple of meters which use accelerometers, rate-gyro sensors, and magnetic sensors to track the orientation and position of the ROV. The Smart Tether greatly increases the accuracy of our ROV localization which in turn helps us create better maps.

In each of our experiments we took turns piloting the ROV, logging data and sketching maps, recording sonar and Smart Tether data, and working the Smart Tether. We started off using the sonar to take horizontal scans of the underwater cave, but we weren't able to get that far into the cave before running out of tether. We decided to add the 80 meter extension to our 40 meter Smart Tether, which allowed us to venture much deeper into the cave. This time we attached the sonar vertically and got some great scans with well-defined cistern-like walls. We ran across many fish, jellyfish, and even an octopus which grabbed onto the ROV. After backing out of the cave, we deployed one more time with the Smart Tether extension to take horizontal sonar scans. We ultimately got about 60 meters in before turning back. Before leaving, we made sure to shoot some underwater video of the ROV with one of the GoPros we brought along.

If all goes well, we should be able to use this data to create 3D maps of the caves using a combination of the horizontal and vertical sonar scans for mapping and Smart Tether logs for localization.

Ethnic Studies 410 Cultural Project - Water and Society

My cultural project relates to the water resources here on Malta. In ES 410, before we left, we learned about the limited water resources that are effecting Malta today and we looked into a little bit of how the government and people were dealing with the insufficient amount of freshwater. Coming to the island, I've been able to get a first hand look at the severity of the shortage and Maltese opinions on it.

Malta's water history is very interesting. The islands of Malta and Gozo is composed of five principle layers; Lower

Coralline Limestone, GlobigerinaLimestone, Blue Clay, Greensand, and Upper Coralline Limestone. Just under the Lower Coralline Limestone layer and above the impermeable Blue Clay level sits two natural freshwater aquifers, the Main Mean Sea Level Aquiferand the Perched Aquifer, respectively. Historically, Malta has used these aquifers for their freshwater, however, today the water is being used faster than it can be replenished by rain and natural permeability of the layers. (Source #1)

Malta's population has grown significantly in past years and continues to grow today.

Just under 400,000 people populate this tiny nation, with a growth rate of 0.42% in 2005, according to the CIA World Factbook. (Source #2) All those people inhabiting the islands require freshwater and lots of it. About one third of Malta's freshwater comes from three aging desalination plants that use Reverse osmosis to extract the salt out of the saltwater from the Mediterranean. Another third is taken from the rapidly shrinking aquifers through manmade boreholes that drill down to the aquifer and pump up water completely free of charge. About one quarter is received through the Water Services' boreholes and the rest comes from small, private reverse osmosis plants or from the islands plentiful private cisterns that collect and store the meager amount of annual rainfall. (Source #3)

In Malta, I've talked briefly with Ph.D student, Keith Buhagiar, a local archeologist interested in the ancient and medieval water management systems spread throughout the islands. He discussed about the differences between wells and cisterns and their creation. Wells are the most ancient water system, and was man's attempt to obtain water by digging vertically down below the spot where water is required. Usually, these wells are circular or square shape vertical shafts. This picture shows a dried up well found in Sicily. (Source #4)

Alternatively, cisterns are more for the collection and storage of water. They were built either through rock-excavation or built at ground level through the use of masonry. Above ground cisterns were not as popular because of their consistent need for maintenance and repair. (Source #4) The picture shows a sonar mosaic of the inside of the Ta-Silg cistern in Malta. Ta-Silg is one of the oldest places with a cistern dating back about 3000 years and living through multiple occupations from the original Temple People to the Phoenicians to the Romans. Some cisterns are quite complicated, like the Ta-Silg cistern, with many rooms and tunnels, while others are simply bell-shaped or circular or rectangular shafts cut into the ground. Sometimes multiple cisterns are clustered together and are connected through small channels. (Source #5)

The situation in Malta changes severity depending on who is giving the opinion. Some don't see the scarcity of water at all while others are being hit very hard with it. Some private homes and farms still use the cisterns and wells settled on their property for various purposes from agricultural water to filtering it for daily use, however, most still rely heavily on the reverse osmosis plants and the shrinking aquifers. With Malta's dependence on tourism and it's increasing population, one thing is for certain, whether the water scarcity is felt by all or not, something must be done to conserve or collect freshwater for the future of Malta. Within the next few days, I am meeting with four members of the Malta Water Association for interviews on this topic. I am hoping to get some good information on their opinions on the water shortage and where this small, heavily populated country is headed.

Sources:

#1 - Malta Water Association (http://maltawater.org/index.php/themes/geological-habitat-of-maltas-aquifers)

#2 - CIA World Fact-Book (https://www.cia.gov/library/publications/the-world-factbook/geos/mt.html)

#3 - Malta Takes Control, IEEE Article (http://spectrum.ieee.org/energy/environment/maltas-smart-grid-solution/0)

#4 - Keith Buhagiar Presentation on "Maltese Ancient and Late Medieval Water Management Systems" on 3/4/12

#5 - Tour of Ta-Silg Temple Site by David Cardona on 3/13/12

Picture Sources:

Picture #1: British Geological Survey (http://www.bgs.ac.uk/research/groundwater/quality/Malta.html)

Picture #2: Malta Takes Control, IEEE Article (http://spectrum.ieee.org/energy/environment/maltas-smart-grid-solution/0)

Picture #3: Picture Taken on Site at Gozo Citadel on 3/12/12

Picture #4: Picture Taken on Site in Palermo, Sicily on 3/6/12

Picture #5: Ta-Silg Mosaic Constructed by Erik on 3/13/12

Picture #6: CIA World Factbook (https://www.cia.gov/library/publications/the-world-factbook/geos/mt.html)

Conquering 9 Cisterns and Welcoming Princeton Students!

It was a very warm day in Gozo today. We got to the farms outside of Victoria, set up our equipment and generator and proceeded to run through 9 cisterns, quickly and efficiently gathering sonar and video and then pulling back up to start again!

Some of the cisterns were quite exciting, like Cistern #1 which we found the hard way was filled with roots! As the ROV was pulled out of the cistern, a blanket of roots covered the entire body. A local farmer helped us to pull the roots out of the motors and off the ROV.

By the last cistern, we were on a roll. We were able to set up, deploy the ROV, scan, and pull the ROV back up in less than 10 minutes! We did have one bump in the road on this cistern, where we forgot to record our scan data, but it was quickly resolved.

When we got home to the apartments, three of the four Princeton Students were already there. We were introduced to Drew, Austin and Yingxue and were informed that Anna was out on a

quick trip to the University of Malta with Jane. The Cal Poly students and the Princeton students decided to take a quick trip to the rocky shore down the road from our apartments and jump in the water. Besides the freezing water, all Cal Poly students and faculty, minus Billy and Jane, managed to get in, even if for just a few seconds.

We returned to the apartment, washed up and ate a great dinner with all 14 of us! Afterwards Timmy came to say goodbye to Zoe and Jane, for the were leaving in the morning. They are very sad to be leaving during such a great time, but they are quite excited to be able to go home again.

Quite a busy and fun day! More tomorrow!

Gozo Cistern Exploration

Today, we took the ferry over to Gozo to explore 2 cisterns from last year and 1 new cistern all at the Citadel on the island of Gozo. In all three of the cisterns we visited today, the water was very murky causing no line of site (even with lasers); therefore, we only were only able to get sonar data and ROV sensor measurements at the bottom of the cisterns. Specifically, we were able to get really good scans of one of the cisterns revisited, nicknamed "The Keyhole". The scans last year from this site included some holes which were virtually filled. With the new data, we can estimate the accuracy of how well our hole filling algorithm is working.

After collecting data, our guide, George Azzopardi, gave us a quick tour of the Museum of Archaeology at the Citadel. The museum was really interesting with many artifacts from pottery to ancient utensils and figurines. After the tour, we stopped by a beautiful scenic site named "Azure Window" seen in the image below.

On the way back to the ferry, we stopped by the site that we will be visited on Thursday and Friday. The location was in a beautiful grassy field off of a very narrow gravel road. More will be posted about this place later this week.


Shortly after returning to the apartments, Chris Clark arrived! He kindly greeted us with groceries filled with delicious snacks :) Dinner was filled with many adventurous and personal stories about each of the members on the team. Another highlight of the day was submitting one of our papers to the IROS 2012 conference. This paper focused on the algorithm developed throughout the past year on mapping the cisterns visited last year, which will likely be used continually throughout the ongoing Malta Cistern Mapping Project.