Remote sensing estimation method for dissolved phosphorus concentration in water bodies

Abstract

A remote sensing estimation method for dissolved phosphorus concentration in water bodies, comprising: step 1: firstly using a satellite remote sensing sensor to measure the electromagnetic wave signal of the water surface; step 2: calculating the water surface remote sensing reflectivity R through atmospheric correction rs ; Step 3: Calculate the dissolved phosphorus concentration C in water TDP . Combined with other structures, the defect that the remote sensing technology in the prior art cannot estimate the dissolved phosphorus concentration is effectively avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of dissolved phosphorus concentration estimation, and in particular relates to a remote sensing estimation method for dissolved phosphorus concentration in water bodies. Background Art

[0002] Phosphorus is the 15th chemical element, symbol P. It is in the third period and group VA of the periodic table. Phosphorus is the main nutrient element for the growth of aquatic plants in water bodies. Phosphorus in water bodies can be divided into particulate phosphorus and dissolved phosphorus. Dissolved phosphorus dissolves in water and is easily absorbed by large aquatic plants, phytoplankton, bacteria, etc. It plays an indispensable role in the primary production process and energy flow of aquatic ecosystems. At the same time, excess phosphorus deteriorates water quality and is the main source of eutrophication of water bodies. Therefore, monitoring the phosphorus concentration in water bodies is an important part of water ecological environment monitoring and a prerequisite for water environment governance.

[0003] Traditionally, the determination of dissolved phosphorus concentration in water can be done by ion chromatography, molybdenum antimony light resistance method, stannous oxide molybdenum blue method, malachite green-phosphomolybdic acid method, etc. These methods require the collection of water samples first and then measurement in the laboratory. Limited by the sampling points, sampling observations can only obtain observation values ​​of discrete sampling points, and cannot synchronously obtain the dissolved phosphorus concentration of the entire water area. The technology of estimating phosphorus concentration using satellite remote sensing data has also been developed in recent years, and some remote sensing estimation models for total phosphorus concentration or particulate phosphorus concentration have been constructed. However, existing remote sensing technology cannot estimate dissolved phosphorus concentration. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a remote sensing estimation method for dissolved phosphorus concentration in water bodies, which effectively avoids the defect that the remote sensing technology in the prior art cannot estimate the dissolved phosphorus concentration.

[0005] In order to overcome the deficiencies in the prior art, the present invention provides a solution for a remote sensing estimation method of dissolved phosphorus concentration in water, which is as follows:

[0006] A remote sensing estimation method for dissolved phosphorus concentration in water bodies, comprising:

[0007] Step 1: First, use satellite remote sensing sensors to measure the electromagnetic wave signals on the water surface;

[0008] Step 2: Calculate the water surface remote sensing reflectivity R through atmospheric correction rs ;

[0009] Step 3: Calculate the dissolved phosphorus concentration C in water TDP .

[0010] Furthermore, the satellite remote sensing sensor has spectral channels of 745, 560 and 443 nm.

[0011] Furthermore, the step 3 specifically includes:

[0012] Step 3-1: Calculate the reflectivity coefficient r rs (λ);

[0013] Step 3-2: Calculate the scattering weight coefficient u(λ);

[0014] Step 3-3: Calculate the absorption coefficient a(745);

[0015] Step 3-4: Calculate the backscatter coefficient b b (745);

[0016] Step 3-5: Calculate the wavelength index Y;

[0017] Step 3-6: Calculate b b (λ);

[0018] Step 3-7: Calculate the intermediate transition parameter a nw (443);

[0019] Step 3-8: Calculate the absorption coefficient a p (443);

[0020] Step 3-9: Calculate the absorption coefficient a CDOM (443);

[0021] Step 3-10: Calculate the absorption coefficient a CDOM (254);

[0022] Step 3-11: Calculate the dissolved phosphorus concentration C in water TDP .

[0023] Furthermore, the reflectivity coefficient r rs The calculation formula of (λ) is: Among them, r rs (λ) is the reflectivity coefficient, λ is the wavelength, R rs (*) is the reflectance value observed at *nm wavelength;

[0024] The calculation formula of the scattering weight coefficient u(λ) is: g 0 =0.084,g 1 =0.17, where u(*) is the scattering weight coefficient for the * wavelength.

[0025] Furthermore, the calculation formula of the absorption coefficient a(745) is: a(745)=a w (745)+33.02*R rs (745)+0.177, where a(*) is the absorption coefficient of water at *nm wavelength, a w (*) is the absorption coefficient of pure water at *nm wavelength;

[0026] The backscatter coefficient b b The calculation formula of (745) is: Among them, b w (*) is the backscattering coefficient of pure water at *nm wavelength.

[0027] Furthermore, the calculation formula of the wavelength index Y is:

[0028]

[0029] The b b (λ) includes b b (443) and b b (555), and its calculation formula is:

[0030]

[0031] Furthermore, the intermediate transition parameter a nw The calculation formula of (443) is:

[0032]

[0033] The absorption coefficient a p The calculation formula of (443) is: p (443) = 1.686*b b (555) 0.512 , where a p (443) is specifically the absorption coefficient of particles at 443 nm.

[0034] Furthermore, the absorption coefficient a CDOM The calculation formula of (443) is: CDOM (443) = a nw (443)-a p (443);

[0035] The absorption coefficient a CDOM The calculation formula of (254) is:

[0036] in,

[0037] a CDOM(*) is the absorption coefficient of xanthin at *nm, and S is the slope coefficient.

[0038] Furthermore, the dissolved phosphorus concentration in the water body is C TDP The calculation formula is: C TDP =6.48*a CDOM (254)-86.785.

[0039] The beneficial effects of the present invention are:

[0040] The present invention provides a technical method for estimating the concentration of dissolved phosphorus in lake water based on satellite remote sensing images. The technology can be applied to inland water bodies to provide support for water ecological environment monitoring and eutrophication assessment. It effectively avoids the defect that the remote sensing technology in the prior art cannot estimate the concentration of dissolved phosphorus. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a partial flow chart of the remote sensing estimation method for dissolved phosphorus concentration in water body of the present invention.

[0042] Figure 2 It is a schematic diagram of dissolved phosphorus concentrations in Taihu Lake in spring, summer, autumn and winter in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0044] like Figure 1-Figure 2 As shown in Figure 2, the remote sensing estimation method for dissolved phosphorus concentration in water bodies includes:

[0045] Step 1: First, use satellite remote sensing sensors to measure the electromagnetic wave signals on the water surface;

[0046] Step 2: Calculate the water surface remote sensing reflectivity R through atmospheric correction rs ;

[0047] Step 3: Calculate the dissolved phosphorus concentration C in water TDP .

[0048] The satellite remote sensing sensor has spectral channels of 745, 560 and 443 nm.

[0049] The step 3 specifically includes:

[0050] Step 3-1: Calculate the reflectivity coefficient r rs (λ);

[0051] Step 3-2: Calculate the scattering weight coefficient u(λ);

[0052] Step 3-3: Calculate the absorption coefficient a(745);

[0053] Step 3-4: Calculate the backscatter coefficient b b (745);

[0054] Step 3-5: Calculate the wavelength index Y;

[0055] Step 3-6: Calculate b b (λ);

[0056] Step 3-7: Calculate the intermediate transition parameter a nw (443);

[0057] Step 3-8: Calculate the absorption coefficient a p (443);

[0058] Step 3-9: Calculate the absorption coefficient a CDOM (443);

[0059] Step 3-10: Calculate the absorption coefficient a CDOM (254);

[0060] Step 3-11: Calculate the dissolved phosphorus concentration C in water TDP .

[0061] The reflectivity coefficient r rs The calculation formula of (λ) is: Among them, r rs (λ) is the reflectivity coefficient, λ is the wavelength, R rs (*) is the reflectance value observed at *nm wavelength (calculated from satellite observation data after atmospheric correction);

[0062] The calculation formula of the scattering weight coefficient u(λ) is: g 0 =0.084,g 1 =0.17, where u(*) is the scattering weight coefficient for the * wavelength.

[0063] The calculation formula of the absorption coefficient a(745) is: a(745)=a w (745)+33.02*R rs (745)+0.177, where a(*) is the absorption coefficient of water at *nm wavelength, a w (*) is the absorption coefficient of pure water at *nm wavelength (it is a constant and can be obtained by referring to the data of pure water absorption coefficient);

[0064] The backscatter coefficient b b The calculation formula of (745) is: Among them, b w(*) is the backscattering coefficient of pure water at *nm wavelength (it is a constant and can be obtained by referring to the pure water backscattering coefficient data).

[0065] The calculation formula of the wavelength index Y is:

[0066] The b b (λ) includes b b (443) and b b (555), and its calculation formula is:

[0067]

[0068] The intermediate transition parameter a nw The calculation formula of (443) is:

[0069] The absorption coefficient a p The calculation formula of (443) is: p (443) = 1.686*b b (555) 0.512 , where a p (443) is specifically the absorption coefficient of particles at 443 nm;

[0070] The absorption coefficient a CDOM The calculation formula of (443) is: CDOM (443) = a nw (443)-a p (443);

[0071] The absorption coefficient a CDOM The calculation formula of (254) is:

[0072] in,

[0073] a CDOM (*) is the absorption coefficient of xanthin at *nm, and S is the slope coefficient.

[0074] The dissolved phosphorus concentration in the water body C TDP The calculation formula is: C TDP =6.48*a CDOM (254)-86.785.

[0075] The present invention is proposed in view of my country's water ecological environment and is suitable for estimating the dissolved phosphorus concentration in inland water bodies. Since dissolved phosphorus is a nutrient that can be directly absorbed by aquatic plants, phytoplankton, bacteria, etc., the estimation of the concentration of this parameter is of great significance for analyzing the nutrient cycle in water bodies and studying water ecological degradation.

[0076] The specific embodiments are as follows:

[0077] First, download the GOCI satellite data of Taihu Lake from 2011 to 2020 from the Internet. The specific website is http: / / kosc.kiost.ac.kr / eng / p10 / kosc_p11.html, Then, according to the usual data processing method, the GOCI data is atmospherically corrected and the remote sensing reflectance R is calculated. rs .

[0078] Secondly, the dissolved phosphorus concentration was calculated using the following formula:

[0079]

[0080]

[0081] Among them, r rs (λ) is the reflectivity coefficient, λ is the wavelength, C TDP is the dissolved phosphorus concentration, R rs (*) is the reflectance value observed at *nm wavelength (calculated from satellite observation data after atmospheric correction), a(*) is the absorption coefficient of water at *nm wavelength, u(*) is the scattering weight coefficient at *nm wavelength, a w (*) is the absorption coefficient of pure water at *nm wavelength (a constant, which can be obtained by referring to the data of pure water absorption coefficient), b b (*) is the backscattering coefficient of water, Y is the wavelength index, b w (*) is the backscattering coefficient of pure water at *nm wavelength (a constant, which can be obtained by referring to the data of pure water backscattering coefficient), a nw (443) is the intermediate transition parameter, a p (443) is the absorption coefficient of particles at 443 nm, a CDOM (443) is the absorption coefficient of xanthophyll at *nm, and S is the slope coefficient.

[0082] The calculation results are as follows Figure 2 As shown in the figure (there are a lot of aquatic plants in the eastern part of Taihu Lake, so some areas of the eastern part of Taihu Lake are not calculated), the figure shows that there are large differences in the dissolved phosphorus concentration in the water body in different seasons of spring, summer, autumn and winter. It is higher in winter and spring and the lowest in summer. In addition, in terms of spatial distribution, the southwestern lake area is higher than the northern lake area. From the west to the east of Taihu Lake and from the southwest to the north, the dissolved phosphorus concentration tends to decrease.

[0083] The present invention has been described above in an illustrative manner using embodiments. Those skilled in the art should understand that the present disclosure is not limited to the embodiments described above, and that various changes, modifications and substitutions can be made without departing from the scope of the present invention.

Claims

1. A remote sensing estimation method for dissolved phosphorus concentration in water, characterized in that: include: Step 1: First, use satellite remote sensing sensors to measure the electromagnetic wave signals on the water surface; Step 2: Calculate the water surface remote sensing reflectivity R through atmospheric correction rs ; Step 3: Calculate the dissolved phosphorus concentration C in water TDP ; The step 3 specifically includes: Step 3-1: Calculate the reflectivity coefficient r rs (λ); Step 3-2: Calculate the scattering weight coefficient u(λ); Step 3-3: Calculate the absorption coefficient a(745); Step 3-4: Calculate the backscatter coefficient b b (745); Step 3-5: Calculate the wavelength index Y; Step 3-6: Calculate b b (λ); Step 3-7: Calculate the intermediate transition parameter a nw (443); Step 3-8: Calculate the absorption coefficient a p (443); Step 3-9: Calculate the absorption coefficient a CDOM (443); Step 3-10: Calculate the absorption coefficient a CDOM (254); Step 3-11: Calculate the dissolved phosphorus concentration C in water TDP ; The reflectivity coefficient r rs The calculation formula of (λ) is: Among them, r rs (λ) is the reflectivity coefficient, λ is the wavelength, R rs (*) is the reflectance value observed at *nm wavelength; The calculation formula of the scattering weight coefficient u(λ) is: g0=0.084, g1=0.17, where u(*) is the scattering weight coefficient of the * wavelength; The calculation formula of the absorption coefficient a(745) is: a(745)=a w (745)+33.02*R rs (745)+0.177, where a(*) is the absorption coefficient of water at *nm wavelength, a w (*) is the absorption coefficient of pure water at *nm wavelength; The backscatter coefficient b b The calculation formula of (745) is: Among them, b w (*) is the backscattering coefficient of pure water at *nm wavelength; The calculation formula of the wavelength index Y is: The b b (λ) includes b b (443) and b b (555), and its calculation formula is: The intermediate transition parameter a nw The calculation formula of (443) is: The absorption coefficient a p The calculation formula of (443) is: p (443) = 1.686*b b (555) 0.512 , where a p (443) is specifically the absorption coefficient of particles at 443 nm; The absorption coefficient a CDOM The calculation formula of (443) is: CDOM (443) = a nw (443)-a p (443); The absorption coefficient a CDOM The calculation formula of (254) is: CDOM (254) = a CDOM (443)*exp(-S*(254-443)), Among them, a CDOM (*) is the absorption coefficient of xanthin at *nm, S is the slope coefficient; The dissolved phosphorus concentration in the water body C TDP The calculation formula is: C TDP =6.48*a CDOM (254)-86.

785.

2. The remote sensing estimation method for dissolved phosphorus concentration in water according to claim 1, characterized in that: The satellite remote sensing sensor has spectral channels of 745, 560 and 443 nm.

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