An Improved Model for Chlorophyll-a Concentration Retrieval in Coastal Waters Based on UAV-Borne Hyperspectral Imagery: A Case Study in Qingdao, China

Gai, Yingying; Yu, Dingfeng; Zhou, Yan; Yang, Lei; Chen, Chao; Chen, Jun

doi:10.3390/w12102769

Cited by 19 publications

(17 citation statements)

References 73 publications

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“…However, the partial processes of BRL may still be difficult to obtain as well as a validation limitation were employed on 1 to 5 August 2007, on which the study area was covered by clouds. To solve the problem of climate impacts, the platforms of unmanned aerial vehicles can be employed to monitor lakes [42].…”

Section: Validity Of the Algorithmmentioning

confidence: 99%

A New Algorithm for Monitoring Backflow from River to Lake (BRL) Using Satellite Images: A Case of Poyang Lake, China

Jiang

Liu

2021

Water

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Backflow from river to lake (BRL) usually happens in inland lakes and affects water exchange, matter migration, and variations in the water quality and eco-environment. However, at present, discharge data derived from hydrological stations are the only way to monitor BRL, and the influence scope of BRL has not been monitored through hydrological stations. To address this problem, we propose a novel algorithm to monitor BRL using satellite images of Poyang Lake (the largest freshwater lake in China). The following results were obtained: (1) According to the difference in suspended sediment from rivers and lakes, an algorithm using the total suspended sediment (TSS), which was used as a tracer, was designed for monitoring BRL in Poyang Lake. (2) An innovative extraction method for the mutation line using the TSS was developed to analyze BRL via satellite images. A gradient variation method was developed to extract the mutation line accurately. (3) The satellites with daily acquisition or higher-frequency resolution images (e.g., Moderate-Resolution Imaging Spectroradiometer (MODIS)) were satisfactory for monitoring the characteristics of BRL. The MODIS-derived band combination Rrs(645) − Rrs(859))/(Rrs(555) − Rrs(859) yielded a higher fitting accuracy (R2 = 0.858, RMSE = 10.25 mg/L) derived from an exponential model, which was helpful to highlighting the mutation line. (4) The important parameters of BRL, such as the beginning time, the duration, the end time, and the influence scope, were quantitatively determined by judging the movement of the mutation line. This algorithm was applied to quickly and effectively extract the information of two instances of BRL in Poyang Lake in July 2000 and July to August 2007, and the results were accurate and reasonable. This algorithm can save a great deal on monitoring costs. A BRL monitoring algorithm using remote sensing is an efficient government measure supplement to address the limitations of hydrological stations. These results provide technological support for lake management and can serve as a valuable reference for water bodies similar to Poyang Lake worldwide.

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Section: Validity Of the Algorithmmentioning

confidence: 99%

A New Algorithm for Monitoring Backflow from River to Lake (BRL) Using Satellite Images: A Case of Poyang Lake, China

Jiang

Liu

2021

Water

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“…One of the water quality parameters that can be used to determine the level of The Interaction of Chlorophyll-a and Total Suspended Matter along the Western Semarang Bay, Indonesia, Based on Measurement and Retrieval of Sentinel 3 Lilik Maslukah 1* , Dwi Haryo Ismunarti 1 , Sugeng Widada 1 , Nur Fikri Sandi 2 , Hanif Budi Prayitno 3 eutrophication is the abundance of algae in the water (Marlian et al, 2015;Poddar et al, 2019; Moutzouris-Sidiris & Topouzelis 2021), and its abundance can be estimated by using the chlorophyll-a measurement. The chlorophyll-a concentration can describe the various factors that happen because of human activity (Gai, et al, 2020). Besides chlorophyll-a, total suspended materials (TSM) is also a determining parameter for water quality.…”

Section: Introductionmentioning

confidence: 99%

The Interaction of Chlorophyll-a and Total Suspended Matter along the Western Semarang Bay, Indonesia, Based on Measurement and Retrieval of Sentinel 3

Maslukah¹,

Ismunarti²,

Widada³

et al. 2022

J. Ecol. Eng.

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The Kendal Regency area is one of the areas on the northern coast of Central Java that has been experiencing rapid industrial development. The high human activity in this area will impact the quality of water in these surrounding areas and affect the fertility of the waters. The concentrations of chlorophyll-a (Chl-a) and total suspended matter (TSM) are major water quality parameters that can be retrieved using remotely sensed data. The retrieval satellite of the 3 OLCI chosen in this study has a 300 m spatial resolution. This study aimed to see the distribution and effect of total suspended matter (TSM) on chlorophyll-a based on measurement and retrieval of Sentinel 3 imagery using the linear regression method. The results show the chlorophyll-a distribution and the value from retrieval satellite are higher and occur over larger surface area compared to chlorophyll-a measurements. The linear regression model of chlorophyll-a by retrieval satellite imagery and measurement is y = 0.65x + 4.65 with R 2 = 0.54. The presence of high amounts of suspended solids in the waters causes disturbances in the reflectance values, which are recorded by the retrieval of satellite. The model regression chlorophyll-a with TSM accuracy from retrieval satellite results in the equation y = -0.0416x + 5.14 (R 2 = 0.45, p = 0.05, n = 13). The determination (R 2 ) coefficient value is 0.445, which means that suspended solids have a 44.5% effect on chlorophyll-a and 55.5% is influenced by other factors and not examined in this study. The results show that TSM has an influence on the accuracy of chlorophyll-a and retrieval satellite recording can be disrupted if waters have high turbidity.

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“…Therefore, water transparency is a key parameter for describing the optical properties in the water body. Water transparency is closely related to many environmental parameters, such as chlorophyll-a (Chl-a) [2][3][4], phytoplankton biomass [5], total suspended matter (TSM) [6], nutritional status [7], sea surface salinity [8], total nitrogen and total phosphorus [9], and widely used as evaluation indicators of marine environmental quality [10].…”

Section: Introductionmentioning

confidence: 99%

Variations of Water Transparency and Impact Factors in the Bohai and Yellow Seas from Satellite Observations

Zhou

Yang

et al. 2021

Remote Sensing

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Water transparency, measured with Secchi disk depth (SDD), is an important parameter for describing the optical properties of a water body. This study evaluates variations of SDD and related impact factors in the Bohai and Yellow Seas (BYS). Based on a new mechanistic model proposed by Lee et al. (2015) applied to MODIS remote sensing reflectance data, climatological SDD variation from 2003 to 2019 was estimated. The annual mean images showed an increasing trend from the coastal zone to the deep ocean. Lower values were found in the Bohai Sea (BHS), while higher values observed in the center of the southern Yellow Sea (SYS). Additionally, the entire sea has shown a decreasing temporal tend, with the variation rate lowest in the BHS at 0.003 m y−1, and highest in the SYS at 0.015 m y−1. However, the weak increasing trend that appeared since 2017 suggests that water quality seems to have improved. Further, it displayed seasonal patterns of low in winter and spring and high in summer and autumn. The empirical orthogonal function (EOF) analysis of SDD variations over the BYS, shows that the first SDD EOF mode is the highest, strongly correlated with total suspended matter. With the high correlation coefficients of chromophoric dissolved organic matter, it illustrates that the SDD variation is mainly dominated by the optical components in the seawater, although correlation with chlorophyll-a is the weakest. The second and third EOF modes show that photosynthetically available radiation, sea surface temperature, sea surface salinity, and wind speed are the main covariates that cause SDD changes. Water transparency evaluation on a long-term scale is essential for water quality monitoring and marine ecosystem protection.

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An Improved Model for Chlorophyll-a Concentration Retrieval in Coastal Waters Based on UAV-Borne Hyperspectral Imagery: A Case Study in Qingdao, China

Cited by 19 publications

References 73 publications

A New Algorithm for Monitoring Backflow from River to Lake (BRL) Using Satellite Images: A Case of Poyang Lake, China

A New Algorithm for Monitoring Backflow from River to Lake (BRL) Using Satellite Images: A Case of Poyang Lake, China

The Interaction of Chlorophyll-a and Total Suspended Matter along the Western Semarang Bay, Indonesia, Based on Measurement and Retrieval of Sentinel 3

Variations of Water Transparency and Impact Factors in the Bohai and Yellow Seas from Satellite Observations

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