Research Interview with Nelson da Luz:
Author: Stephen Stamegna
Background: Nelson da Luz is a Ph.D. student in the Environmental and Water Resources engineering program and a graduate member of the Kumpel Research Group at the University of Massachusetts Amherst currently pursuing a degree in the field of drinking water quality and supply.
Q: Could you tell me a little bit about your project?
A: My main project that I’m focused on is drinking water quality sampling programs (drawing a sample of water from a portion of a system to analyze it for different parameters). So, what I’m thinking about is what makes a sampling program “representative.” In other words, is the program intended to represent the entire distribution system or part of the system? Another broad question that I’m exploring that is dependent on the concept of “representation” is whether the sampling program is protective of human health or if it meets some other objective. In relation to these questions, I’m investigating if a sampling program is representing a specific thing, when and where is the best time and place to sample for different water quality parameters.
Q: What do you hope to achieve through this research?
A: The reason behind this research is that the guidance that is provided to utilities is often very broad. Regulation agencies simply tell utilities to make their sampling programs “representative,” but do not provide much guidance as to what this entails. At the end of the day, hopefully this research will provide agencies and utilities with a better idea of what “representative” means. Adapting this term to specific goals is also important rather than using it as a blanket term.
Q: As of now, what are your materials and methods for conducting your study?
A: I’m working with an EPANET water quality model that simulates a network of pipes and the junctions at which water is withdrawn from the network for sampling purposes. The first step is to run a hydraulic model of the distribution system to validate the hydraulics of the system and eliminate errors. For instance, ensuring that sufficient quantities of water are flowing throughout the entire system and that there is enough pressure at all locations. The second step is using the EPANET model to analyze water quality parameters throughout the distribution system. The main parameter that I’m examining is chlorine concentration. In EPANET, this means that you have to assign a chlorine dose at the sources (treatment plants or any water source) and then assign reaction coefficients for chlorine decay. Then you run the model that follows the logic of a mass balance to determine the differential quantities of chlorine throughout the distribution system.
Q: Have you experienced any complications in your research?
A: Yes. For some reason, when you first look at the display on EPANET, it looks like an accurate map of a distribution system. However, the scale that is shown on the screen is not always accurate. In other words, a pipe length in one section appears to be the same as a pipe in another section. In reality, they are not the same length. In the beginning, I assumed the map was to scale. Now, I’m going back to ensure that the model in EPANET matches real physical properties such as pipe length. I also have had some complications when it comes to coding; it is a bit of a process to determine the optimal data structures to use for my analyses.
Q: Have you figured out how to solve these complications?
A: Most of them, yes. I’ve been able to use a combination of tools in ArcGIS and coding in R programming language to correct many of the issues with the EPANET model.
Q: How does your research relate to the research group at large?
A: My research examines a continuous supply distribution system while a lot of what the research group focuses on is intermittent water supply. However, the overarching questions around when and where to sample for water quality still remain regardless of whether you are sampling in a continuous distribution system, intermittent distribution system, or even a natural water system.
Q: Why did you get involved in research?
A: At the core of this question, I have a desire to contribute to the studies that revolve around helping people to obtain clean drinking water. In 2014, I went on a trip to Haiti and I saw a lot of the issues surrounding water scarcity. I felt a strong call to serve the mission of helping people to get clean water. As time progressed, there were opportunities in research that were presented to me. I completed my bachelor’s and master’s degrees at Manhattan College which is where I was first exposed to research. Through those experiences, I felt that research was a great avenue to use my skills to serve this greater mission.
Q: Why do you like your project in particular?
A: I like it because it explores questions that not many people have dedicated a lot of thought to at this level of detail. I’m also able to use a large variety of tools to achieve my goals; I’m using EPANET, coding in R, and ArcGIS. This keeps the project exciting and different.