Next Article in Journal
Stochastic Hybrid Event Based and Continuous Approach to Derive Flood Frequency Curve
Previous Article in Journal
Ecology and Conservation of Freshwater Fishes Biodiversity: We Need More Knowledge to Develop Conservation Strategies
Article

Hybrid Approach of Unmanned Aerial Vehicle and Unmanned Surface Vehicle for Assessment of Chlorophyll-a Imagery Using Spectral Indices in Stream, South Korea

Korea Institute of Civil Engineering and Building Technology—Environment Research Institute, Goyangdae-ro, Goyang-si 10223, Korea
*
Author to whom correspondence should be addressed.
Academic Editor: Giuseppe Pezzinga
Water 2021, 13(14), 1930; https://doi.org/10.3390/w13141930
Received: 31 May 2021 / Revised: 1 July 2021 / Accepted: 5 July 2021 / Published: 13 July 2021
(This article belongs to the Section Water Quality and Contamination)
The purpose of this study is to compare the spectral indices for a two-dimensional river algae map using an unmanned aerial vehicle (UAV) and an unmanned surface vehicle (USV) hybrid system. The UAV and USV hybrid systems can overcome the limitation of not being able to effectively compare images of the same region obtained at different times and under different seasonal conditions, when using a method of comparing and analyzing with absolute values in remote sensing. Radiometric correction was performed to minimize the interference that could distort the analysis results of the UAV imagery, and the images were taken under weather conditions that would minimally affect them. Three spectral indices, namely, normalized difference vegetation index (NDVI), normalized green–red difference index (NGRDI), green normalized difference vegetation index (GNDVI), and normalized difference red edge index (NDRE) were compared for the chlorophyll-a images. In field application and correlational analysis, the NDVI was strongly correlated with chlorophyll-a (R2 = 0.88, p < 0.001), and the GNDVI was moderately correlated with chlorophyll-a (R2 = 0.74, p < 0.001). As a result of comparing the chlorophyll-a concentration with the in-situ chlorophyll-a imagery by UAV, we obtained the RMSE of NDVI at 2.25, and the RMSE of GNDVI at 3.41. View Full-Text
Keywords: chlorophyll-a imagery; river; spectral indices; unmanned aerial vehicle; unmanned surface vehicle chlorophyll-a imagery; river; spectral indices; unmanned aerial vehicle; unmanned surface vehicle
Show Figures

Figure 1

MDPI and ACS Style

Kim, E.-J.; Nam, S.-H.; Koo, J.-W.; Hwang, T.-M. Hybrid Approach of Unmanned Aerial Vehicle and Unmanned Surface Vehicle for Assessment of Chlorophyll-a Imagery Using Spectral Indices in Stream, South Korea. Water 2021, 13, 1930. https://doi.org/10.3390/w13141930

AMA Style

Kim E-J, Nam S-H, Koo J-W, Hwang T-M. Hybrid Approach of Unmanned Aerial Vehicle and Unmanned Surface Vehicle for Assessment of Chlorophyll-a Imagery Using Spectral Indices in Stream, South Korea. Water. 2021; 13(14):1930. https://doi.org/10.3390/w13141930

Chicago/Turabian Style

Kim, Eun-Ju, Sook-Hyun Nam, Jae-Wuk Koo, and Tae-Mun Hwang. 2021. "Hybrid Approach of Unmanned Aerial Vehicle and Unmanned Surface Vehicle for Assessment of Chlorophyll-a Imagery Using Spectral Indices in Stream, South Korea" Water 13, no. 14: 1930. https://doi.org/10.3390/w13141930

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop