Combining topography and reflectance indices for better surface water detection

Yuanming Hu, Jisoo Lee, Kyungrock Paik

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


Since the Normalized Difference Water Index (NDWI) was proposed, water indices have served as useful tools for surface water detection. However, existing water indices are highly influenced by atmospheric and other environmental conditions and suffer from limited performance, especially in urban areas. At the core of the limitation is the sole dependency on the spectral distribution of reflectance signals. To overcome this, we propose to utilize topographic data as additional information for better water detection. Accordingly, the new index, namely Combined Water Index (CWI), is developed as the product of the topographic index and the reflectance-based index. These two indices excellently compensate each other: the former is free from noise issues but invariant over time while the latter can capture temporal dynamics of waterbody extents. The CWI is applied to four study areas of different development levels (natural, medium-sized cities, and megalopolis) in the Han River basin, South Korea. The water detection results of the CWI is promising, particularly in the heavily developed urban setting, demonstrated through visual images as well as various statistical measures.

Original languageEnglish
Pages (from-to)38-49
Number of pages12
JournalJournal of Hydro-Environment Research
Publication statusPublished - 2024 Jan

Bibliographical note

Publisher Copyright:
© 2024 International Association for Hydro-environment Engineering and Research, Asia Pacific Division


  • Remote sensing hydrology
  • Water detection
  • Water index
  • Waterbody map

ASJC Scopus subject areas

  • Environmental Engineering
  • Civil and Structural Engineering
  • Environmental Chemistry
  • Water Science and Technology
  • Management, Monitoring, Policy and Law


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