The October 7 Heiland Lecture focused on the importance of scale of modeling in a variety of different situations. Dr. Tissa Illangasekare, Professor of Civil Engineering at Mines, spoke at great length and in hurried detail about a variety of different topics that highlighted the relevance of modeling and attention to scale. Illangasekare is a world known specialist in the area of water and chemical flow through porous media, and after an insightful lecture, it is clear why such a field is of interest not only to geophysicists, but the entire Mines community. “We have to look at groundwater as a sustainable resource,” said Illangasekare, “46% of drinking water is subsurface water.” It is because of this that focusing on how liquids flow through the subsurface is important.
One of the major concerns is the threat of contamination by toxins and other chemicals. “A lot of focus is done in the lab, where we can monitor the situation,” said Illangasekare, “still though, the laboratory is simple, the field is complex.” Illangasekare’s goal is to break down the complexity of the field in to manageable, measurable sections. “We cannot disturb the system, so we use X-rays so we can look at the sample while it is still functioning,” And this is a good thing since, according to Dr. Illangasekare, it can take a very long time to set up a model.
One of Illangasekare’s more insightful projects involves the interaction between the atmosphere and ground. “Many climatologists treat the ground as a basic unchanging element in the system while many earth scientists treat the atmosphere the same way,” Such is not the case in Illangasekare’s laboratory. By analyzing the effects of the atmosphere on the ground during events such as rain or heavy sunlight, Illangasekare has been able to discover how fluids can become trapped into flows instead of permeating upwards to the surface. It was noted that if this experiment were run on a small scale, it would not have been as apparent.
Another realm where the scale can bring about different results was Illangasekare’s analysis of remediation methods depending on the situations, “With small samples you can get most of a pollutant out, on a large scale, not so much… in order to best deal with a problem you must experiment on different levels.” He also stressed that the amount and quality of data can be very important. His lab recently was researching the effective number of boreholes it would take to obtain the needed information to understand a reservoir or rock unit. They found that after a certain point, the data was no longer improving the resolution of the model, though prior to that point each borehole greatly helped the model.
On a more global level, Illangasekare reflected upon how his research can help the global community. With some of the ground/atmospheric models his lab has been able to develop new methods on how to find landmines in regions that are greatly affected by this problem. “We have been able to detect landmines in the lab and have learned how to tell them apart from other objects,” said Illangasekare. His experiments should soon enter a more rigorous testing phase with a wider variety of threatening devices. A more personal quest for Illangasekare involves his work in analyzing the remediation of well water in Sri Lanka, his home country. After the 2004 tsunami, many of the wells along the eastern coast of the country were flooded with saline water, rendering them unusable. The hope was that the salt water would filter out naturally after two years, but when that did not occur, they called in Illangasekare to help model the groundwater flow. Through his work, we now have a better understanding of the flow of these materials through the ground such that if a catastrophe happens again, the crisis can be better averted.