Machine learning approaches to coastal water quality monitoring using GOCI satellite data |
| |
| Authors: | Yong Hoon Kim Ho Kyung Ha Jong-Kuk Choi Sunghyun Ha |
| |
| Institution: | 1. RPS ASA, South Kingstown, RI, USA;2. Department of Ocean Sciences, Inha University, Incheon, South Korea;3. Korea Institute of Ocean Science &4. Technology, Ansan, South Korea;5. School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea |
| |
| Abstract: | Since coastal waters are one of the most vulnerable marine systems to environmental pollution, it is very important to operationally monitor coastal water quality. This study attempts to estimate two major water quality indicators, chlorophyll-a (chl-a) and suspended particulate matter (SPM) concentrations, in coastal environments on the west coast of South Korea using Geostationary Ocean Color Imager (GOCI) satellite data. Three machine learning approaches including random forest, Cubist, and support vector regression (SVR) were evaluated for coastal water quality estimation. In situ measurements (63 samples) collected during four days in 2011 and 2012 were used as reference data. Due to the limited number of samples, leave-one-out cross validation (CV) was used to assess the performance of the water quality estimation models. Results show that SVR outperformed the other two machine learning approaches, yielding calibration R2 of 0.91 and CV root-mean-squared-error (RMSE) of 1.74 mg/m3 (40.7%) for chl-a, and calibration R2 of 0.98 and CV RMSE of 11.42 g/m3 (63.1%) for SPM when using GOCI-derived radiance data. Relative importance of the predictor variables was examined. When GOCI-derived radiance data were used, the ratio of band 2 to band 4 and bands 6 and 5 were the most influential input variables in predicting chl-a and SPM concentrations, respectively. Hourly available GOCI images were useful to discuss spatiotemporal distributions of the water quality parameters with tidal phases in the west coast of Korea. |
| |
| Keywords: | chlorophyll-a concentration suspended particulate matter GOCI water quality machine learning |
|
|
