Two-decade dynamics of MODIS-derived Secchi depth in Peninsula Malaysia waters

Idris, Md. Suffian; Siang, Hing Lee; Amin, Roswati Md; Sidik, Madihah Jafar

doi:10.1016/j.jmarsys.2022.103799

Cited by 5 publications

(5 citation statements)

References 77 publications

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“…The dependence of the penetration of laser rays through water depends on its purity (transparency). This is such a strong and obvious relationship that the penetration depth of a given system is usually given not in the form of the penetration depth expressed in meters of depth, but in the form of a multiple of visibility—the so-called a Secchi disc [ 16 ]. The Secchi disc is a device designed by Pietro Angelo Secchi for measuring the transparency of water.…”

Section: The Use Of a Green Laser In Airborne Lidar Systemsmentioning

confidence: 99%

The Use of Green Laser in LiDAR Bathymetry: State of the Art and Recent Advancements

Szafarczyk

Toś

2022

Sensors

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Bathymetric LiDAR technology is a technology used for simultaneous data acquisition regarding the morphology of the bottom of water reservoirs and the surrounding coastal zone, realized from the air, e.g., by plane or drone. Contrary to the air topographic LiDAR, which uses an infrared wavelength of 1064 nm, bathymetric LiDAR systems additionally use a green wavelength of 532 nm. The green laser can penetrate the water, which makes it possible to measure the depth of shallow water reservoirs, rivers, and coastal sea waters within three Secchi depths. This article presents the theoretical basis for the construction of a green laser. Against the background of other methods of measuring the bottom of water reservoirs, the technology using waves from the visible light range is presented in detail in the assessment of the bottom morphology of shallow water reservoirs. The possibilities of using green laser in lidar bathymetry implemented in particular in non-navigable regions are shown. The results of the researchers’ work on river processes (erosion, sedimentation), design of stream restoration, determination of morphometric parameters of the riverbed, as well as assessment of the topography of the marine coastal bottom zones are summarized. The development direction of lidar bathymetry is discussed.

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Section: The Use Of a Green Laser In Airborne Lidar Systemsmentioning

confidence: 99%

The Use of Green Laser in LiDAR Bathymetry: State of the Art and Recent Advancements

Szafarczyk

Toś

2022

Sensors

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“…For example, D sd ceased to be a useful indicator of chlorophyll a concentration in a eutrophic reservoir when it exceeded 100 mg/m 3 , but was a good predictor of chlorophyll concentration below this threshold (Golubkov and Golubkov, 2024). To address this issue, various algorithms are being developed to derive D sd from satellite data, aiming to interpret empirical data from diverse conditions in large-scale areas (Idris et al, 2022;Msusa et al, 2022;Roy and Das, 2022;Guo et al, 2022a). Nonetheless, field studies directly conducted on water bodies are still necessary to obtain empirical data from a variety of locations for further refinement of algorithms (Zhang et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Patterns of the relationship between the Secchi disk depth and the optical characteristics of water in the Neva Estuary (Baltic Sea): the influence of environmental variables

Golubkov,

Golubkov

2024

Front. Mar. Sci.

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The Secchi disc depth (Dsd) measurement is widely used to monitor eutrophication and the quality of the aquatic environment. This study aimed to investigate the relationship between Dsd and various factors, including the coefficient of attenuation of photosynthetically active radiation [Kd (PAR)], the depth of the euphotic zone (Deu), PAR at the Secchi disk depth (Esd) and the absorption coefficient of PAR (F) in the Neva Estuary, one of largest estuaries of the Baltic Sea. Environmental variables impacting these indices were identified using data collected from midsummer 2012 to 2020. The Dsd values in the estuary ranged from 0.3 to 4.0 m, with an average value of 1.8 m, while the Deu/Dsd ratio ranged from 1.5 to 6.0 with an average value of 2.8. These values were significantly lower than those observed in the open waters of the Baltic Sea. The highest Deu/Dsd ratio was observed in turbid waters characterized by high Kd(PAR) and low Dsd. Contrary to expectations, Dsd did not exhibit a significant relationship with the concentration of chlorophyll a, raising doubts about the utility of historical Dsd data for reconstructing phytoplankton development in the estuary. Principal component analysis did not identify the primary environmental variables strongly affecting the optical characteristics of water. However, recursive partitioning of the dataset using analysis of variance (CART approach) revealed that the concentration of suspended mineral matter (SMM) was the primary predictor of Deu/Dsd, Kd(PAR), and F. This SMM was associated with the frequent resuspension of bottom sediments during windy weather and construction activities in the estuary. Concentrations of suspended organic matter and the depth of the water area were found to be less significant as environmental variables. Furthermore, the CART approach demonstrated that different combinations of environmental variables in estuarine waters could result in similar optical indicator values. To reliably interpret the data and determine the optical characteristics of water in estuaries from Dsd, more complex models incorporating machine learning and neural connections are required. Additionally, reference determinations of Esd in various regions with specific sets of environmental variables would be valuable for comparative analyses and better understanding of estuarine systems.

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“…In recent years, there is increasing trend of applying remote sensing methods to study water transparency. For instance, Idris et al [7] utilized Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data to retrieve water clarity in the Eastern coast of the Malaysian Peninsula and the Malacca Strait and analyzed the seasonal and interannual variations in water clarity within this region. Msusa et al [8] developed a semi-analytical algorithm based on moderateresolution Medium Resolution Imaging Spectrometer (MERIS) satellite data and assessed its performance by utilizing MERIS images obtained over Kasumigaura Lake in Japan.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Water Clarity Using Landsat 8 Imagery in Jiaozhou Bay, China, From 2013 to 2022

Yu,

Qi,

Yang

et al. 2024

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Secchi disk depth (SDD) is a crucial indicator for assessing changes in the water environment. Coastal water transparency varies due to weather, climate, and human activities. Systematic observations are crucial for assessing water quality and ecosystem health. This study used Landsat 8 imagery to investigate the transparency of Jiaozhou Bay (JZB) from 2013 to 2022 and to explore the primary factors influencing transparency changes. Among natural factors, precipitation plays a dominant role in transparency changes. After 2019, there was an increase in rainfall in JZB, which usually leads to reduced transparency. However, the significant improvement in transparency, attributed to a sharp reduction in human activities due to the coronavirus disease 2019 (COVID-19), highlights the substantial impact of human activities on JZB's transparency.

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Two-decade dynamics of MODIS-derived Secchi depth in Peninsula Malaysia waters

Cited by 5 publications

References 77 publications

The Use of Green Laser in LiDAR Bathymetry: State of the Art and Recent Advancements

The Use of Green Laser in LiDAR Bathymetry: State of the Art and Recent Advancements

Patterns of the relationship between the Secchi disk depth and the optical characteristics of water in the Neva Estuary (Baltic Sea): the influence of environmental variables

Monitoring Water Clarity Using Landsat 8 Imagery in Jiaozhou Bay, China, From 2013 to 2022

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