Eutrophic water aquatic vegetation remote sensing extraction method based on alga index frequency method

A technology for aquatic vegetation and algae index, applied in the direction of measuring devices, instruments, optical devices, etc., can solve problems such as errors and inability to truly reflect the evolution process of water ecosystems, and achieve low cost, obvious advantages, innovation, and operation easy effect

Active Publication Date: 2015-05-06
NANJING INST OF GEOGRAPHY & LIMNOLOGY
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Problems solved by technology

Moreover, when the current method inverts the area of ​​aquatic vegetation, it directly removes the areas where algae occurs frequently based on prior knowledge, which will cause large errors in the long-term sequence inversion and cannot truly reflect the evolution of the aquatic ecosystem.

Method used

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  • Eutrophic water aquatic vegetation remote sensing extraction method based on alga index frequency method
  • Eutrophic water aquatic vegetation remote sensing extraction method based on alga index frequency method
  • Eutrophic water aquatic vegetation remote sensing extraction method based on alga index frequency method

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Effect test

Embodiment 1

[0099] figure 2 is the optimal threshold T for the identification of aquatic vegetation FAI Select a schematic.

[0100] Since the original threshold T FAI It is used to discriminate the area of ​​planktonic algae in the water body, so the present invention takes Taihu Lake as an example to improve this threshold, making it suitable for discriminating the distribution of aquatic vegetation. From figure 2 It can be seen from the figure that the comparison with the measured values ​​in the same period (104 measured stations evenly distributed on the lake surface) shows that the threshold T FAIWhen the value is -0.025, the discrimination effect on the vegetation signal in the water area is the best, and the overall accuracy consistent with the measured results is 81.55%.

[0101] image 3 for different thresholds T FAI The comparison chart of the discrimination results, in which the black dots indicate that the measured results are water areas, the black crosses indicate ...

Embodiment 2

[0105] In this embodiment, scheme 2 is used to calculate the distribution of aquatic vegetation in Taihu Lake in 2008-2012, and the obtained results are verified with the measured data of aquatic vegetation in Taihu Lake in 2008-2012 (the measured data are 48 points per year, uniformly distributed, in Figure 5 in 2008 and 2009 are missing one measured point).

[0106] (1) The division of typical growth periods of algae and aquatic vegetation. According to the phenological growth characteristics of algae and aquatic vegetation in Taihu Lake, MODIS images that meet the standards throughout the year are divided into the following three groups:

[0107] Period 1 (algae and aquatic vegetation luxuriant period): June-October;

[0108] Period 2 (coexistence period of accumulating algae and overwintering vegetation): February and March;

[0109] Period 3 (overwintering vegetation period): December of the previous year and January of the current year.

[0110] (2) Calculate the FAI ...

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Abstract

The invention provides an eutrophic water aquatic vegetation remote sensing extraction method based on an alga index frequency method. The eutrophic water aquatic vegetation remote sensing extraction method includes S1, selecting MODIS (moderate resolution imaging spectroradiometer) images of eutrophic water with aquatic vegetation luxuriant and area stable at different periods; S2, subjecting the MODIS images selected to FAI (floating alga index) calculation; S3, according to the FAI, calculating VPF (vegetation signal appearance frequency) of pixels j at the periods; S4, defining VPF threshold values of all periods and calculating the aquatic vegetation area Aav. The eutrophic water aquatic vegetation remote sensing extraction method has the advantages that the influence of floating alga to aquatic vegetation remote sensing inversion is eliminated, and by integrating typical period dividing, frequency judgment and satellite image judgment, the influence of the floating alga and perennial alga bloom areas to the accurate aquatic vegetation area remote sensing inversion is eliminated.

Description

technical field [0001] The invention relates to the technical field of distinguishing algae and aquatic vegetation in the process of water environment remote sensing inversion, in particular to a remote sensing extraction method for aquatic vegetation in eutrophic (frequent algal blooms) waters based on an exponential frequency method. Background technique [0002] Aquatic vegetation has many important ecological and economic values ​​in aquatic ecosystems, such as: providing necessary habitats for aquatic organisms, sediment fixation, nutrient cycle and maintaining fishery production. The deterioration of water quality is often accompanied by a sharp decline in the area of ​​aquatic vegetation, and the distribution of aquatic vegetation often becomes an indicator of water quality and nutrient input in aquatic ecosystems. Therefore, the timely and effective monitoring of the distribution and area of ​​aquatic vegetation plays an extremely important role in the monitoring and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01B11/28
Inventor 刘笑菡张运林施坤周永强
Owner NANJING INST OF GEOGRAPHY & LIMNOLOGY
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