2026-03-27 ノースカロライナ州立大学（NC State）
＜関連情報＞
- https://news.ncsu.edu/2026/03/water-water-everywhere-but-how-to-find-it/
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GL119880
空間スケールが光学地球観測から得られる季節ごとの地表水域の範囲に与える影響 Impact of Spatial Scale on Optical Earth Observation-Derived Seasonal Surface Water Extents
Mollie D. Gaines, Mirela G. Tulbure, Vinicius Perin, Darcy Boast, Henry Castellanos Quiroz, Rebecca Composto, Varun Tiwari, Júlio Caineta
Geophysical Research Letters Published: 05 February 2026
DOI:https://doi.org/10.1029/2025GL119880
Abstract
Landsat-derived products are the most prominent, publicly available sources of large-scale surface water extent data. However, few studies have assessed the limitations of spatial scale on such products. Here, we mapped seasonal surface water extents utilizing high-resolution (4.77 m) PlanetScope Basemap imagery and machine learning. We conducted a pixel-wise comparison of these high resolution classifications with a set of classifications from a moderate resolution (30 m) Landsat product. The vast majority (<?XML:NAMESPACE PREFIX = “[default] http://www.w3.org/1998/Math/MathML” NS = “http://www.w3.org/1998/Math/MathML” />93%) of areas classified as water by the Landsat product were similarly classified by PlanetBasemap; however, only 65%–75% of the PlanetBasemap water area was also classified by the Landsat classes. Of the Landsat classes, only the partial surface water class comparably detects smaller water bodies (widths 50–70 m) with PlanetBasemaps. Our results indicate that higher resolution imagery detects more small water bodies, which are instrumental to better understanding flood dynamics, methane emissions, and downstream water volume and quality.
Plain Language Summary
Surface water bodies—like ponds, rivers, and lakes—are important for ecosystems and human water use. Headwater watersheds, which are made up of smaller water bodies, are particularly vulnerable to climate change. How the size of these water bodies change across seasons is vital for improving our understanding of the impacts of climate change. However, most current water mapping and monitoring products struggle to detect seasonal changes in surface water area. Often, smaller water bodies are missed altogether. In this study, we used over 3,000 high-resolution satellite images to map surface water areas over two years in northern Georgia. These maps showed the seasonal changes in surface water area and detected more surface water than the currently available U.S. surface water extent product. Our high-resolution maps specifically detected more small ponds, rivers, and lakes than the current product. These differences highlight the importance of high-resolution imagery when mapping surface water, particularly when looking at how surface water changes over time.
