January e-Newsletter Community Guest Spotlight with Punwath Prum
Posted Feb 11, 2026
Punwath Prum, PhD candidate, Department of Geology and Environmental Science, University of Pittsburgh
Long-term observations of water quality are critical to understanding how coastal rivers and estuarine ecosystems are responding to climate change and human disturbance. For over 50 years, Landsat satellites have provided the means to observe coastal water quality worldwide, up to every 8 days. This half-century legacy of Landsat observation continues with the successful launch of Landsat 9 in 2020.
The estimation of water quality with satellite imagery relies on the relationship between the concentration of water constituents (e.g. total suspended sediment) and surface reflectance. The long-term monitoring of water quality requires consistent surface reflectance. Since 1984, Landsat sensors have evolved from Thematic Mapper (TM), Enhanced Thematic Mapper (ETM+), Operational Land Imager (OLI) 1, and OLI 2 with each having a different sensitivity. Data inconsistency issues occur when constructing a time-series across multiple sensors. No studies have developed algorithms to address the inconsistency of Landsat surface reflectance data for water quality monitoring across TM, ETM+, OLI1 and OLI2.
My Ph.D. thesis is about to advance the understanding of global changes in the water quality of coastal rivers and estuaries using Landsat data. With financial support from CUAHSI’s Hydroinformatic Innovation Fellowship (HIF), I was able to develop an algorithm to harmonize surface reflectance data across multiple Landsat sensors for water quality monitoring and generate the first global coastal rivers and estuaries surface reflectance database with geolocation data. The dataset is deposited at HydroShare for public use yet is currently under embargo due to the peer review process of the manuscript. The HIF allowed me to develop a proof-of-concept for a proposal and was awarded a NASA FINESST24. In addition, I was able to join several workshops and conferences to network and share my research findings. I presented my research at AGU 2024, ASLO 2024, Hacking Limnology 2025, and colloquium at the Department of Geology and Environmental Science at the University of Pittsburgh.