Publications

Sakuno, Y; Yajima, H; Yoshioka, Y; Sugahara, S; Abd Elbasit, MAM; Adam, E; Chirima, JG (2018). Evaluation of Unified Algorithms for Remote Sensing of Chlorophyll-a and Turbidity in Lake Shinji and Lake Nakaumi of Japan and the Vaal Dam Reservoir of South Africa under Eutrophic and Ultra-Turbid Conditions. WATER, 10(5), 618.

Abstract
We evaluated unified algorithms for remote sensing of chlorophyll-a (Chla) and turbidity in eutrophic and ultra-turbid waters such as Japan's Lake Shinji and Lake Nakaumi (SJNU) and the Vaal Dam Reservoir (VDR) in South Africa. To realize this objective, we used 38 remote sensing reflectance (R-rs), Chla and turbidity datasets collected in these waters between July 2016 and March 2017. As a result, we clarified the following items. As a unified Chla model, we obtained strong correlation (R-2 = 0.7, RMSE = 2 mg m(-3)) using a two-band model (2-BM) and three-band model (3-BM), with R-rs(687)/R-rs(672) and [R-rs(-1)(687) - R-rs(-1)(672)] x R-rs(832). As a unified turbidity model, we obtained strong correlation (R-2 = 0.7, RMSE = 260 NTU) using 2-BM and 3-BM, with R-rs(763)/R-rs(821) and R-rs(810) - [R-rs(730) + R-rs(770)]/2. When targeting the Sentinel-2 Multispectral Imager (MSI) frequency band, we focused on MSI Bands 4 and 5 (R-rs(740) and R-rs(775)) for the Chla algorithm. When optically separating SJNU and VDR data, it is effective to use the slopes of MSI Bands 3 and 4 (R-rs(560) and R-rs(665)) and the slopes of MSI Bands 7 and 9 (R-rs(775) and R-rs(865)).

DOI:
10.3390/w10050618

ISSN:
2073-4441