Monday, April 18, 2016

URSP Student Joshua Murphy Models Groundwater Flow on Mars

I am an Earth Science major with a particular fascination for the geology of other planets, especially Mars. The surface of Mars’s southern hemisphere is heavily cratered and contains features that indicate liquid water once flowed across the surface. Rovers and orbiters have shown that many craters were once the site of flooding or even deep lakes. One thing many people don’t realize about water on land (on Earth as well as Mars) is the importance of groundwater. While there is still much uncertainty about how much precipitation occurred on early Mars, groundwater probably played a major role in supplying the water to create features such as valley networks and lakes.

Computer modelling is one of the main ways we can gain and understanding of how groundwater flows in a particular environment. I am working with Dr. Goldspiel on modeling how the flow of groundwater into a crater lake would be affected by nearby craters. For example, to what extent, if any, do larger, deeper craters divert flow away from a nearby crater? Dr. Goldspiel and I meet every week to discuss my project and what I should try to accomplish for the next week.

I am using a model developed by the U.S. Geological Survey, so I have not (yet!) had to write or change any code for the model itself. Rather, I spend most of my time setting up the particular modeling situations (or grids). It takes a lot of work and problem solving to design a model grid and make sure the simulation runs properly. Once a model has run successfully—which usually take between 3 and 30 minutes—I can begin to analyze and interpret the results. At this point in the semester, I have also begun to devote significant time to writing a paper on my project. A major aspect of this work that I seem to relearn every week is how designing these model grids is at once frustrating, interesting, and satisfying. I often work for a long time with little progress, happily make an apparent breakthrough, then find another problem that needs to be