Simulation Estimation of BOD Content in Water Based on Hyperspectra
WANG Hong-wei1, WANG Bo2, JI Tong3, XU Jun4, JU Feng5, WANG Cai-ling6*
1. Engineering University of CAPF, Xi’an 710086, China
2. Grassland Experiment Station of Yanchi, Yanchi 751506, China
3. College of Grass Industry, Gansu Agricultural University, Lanzhou 730070, China
4. Xi’an Aeronautical University, Xi’an 710077, China
5. Yinchuan Customs District P. R. China, Yinchuan 750000, China
6. Xi’an Shiyou University, Xi’an 710065, China
Abstract：Due to the requirement of continuity and spectral separability, hyperspectral technology has the ability to distinguish different types of the same ground object, and the spectral data acquisition speed is fast, and the operation is simple. Spectral analysis has made outstanding achievements in monitoring water distribution and water indicators. Biochemical oxygen demandis one of the important indicators to evaluate water pollution, the current conventional measuring method for 5 culture method, and this method consumes reagent, complicated operation, more interference factors, determination of time is long, can not reflect the water quality changes in time, can’t early warning of emergent water pollution events in a timely and effective manner, in view of the traditional methods of faults, explore the content of water, BOD estimation based on the technology of hyperspectral and inversion for water quality assessment is of great significance. This test three surface water in xi ’an area as the research area, a total of 60 sites, each site repeat 10 times spectra and the BOD value, average as an original spectrum and the BOD value, Person correlation coefficient method is used to filter the spectrum and the BOD value of sensitive wavebands, and principal component analysis and least square method are used to eliminate spectral index of multicollinearity, BOD water quality index of the multivariate linear regression model and partial least squares regression model. The results were as follows: (1) the BOD sensitive bands were generally distributed at 600～900 nm, and a total of 35 original spectral indicators with significant correlation were screened out, of which the absolute value of the correlation coefficient of 758 nm was the highest (0.418). (2) the accuracy of multiple linear regression model of Z1, Z2 and BOD indexes obtained by principal component analysis (R2=0.565, RMSE=0.007) is good, and the BOD concentration of 0～0.2 and 0.4～0.6 mol·L-1 can be clearly distinguished in the principal component analysis. (3) partial least-squares regression between spectral index and BOD index shows that the model accuracy R2 of the partial least-squares regression model is up to 0.896, RMSEP=0.746 9 (root mean square error with one crossing method). By jack test, it is found that 628 nm has a very significant influence on the BOD content of inversion water body, and the bands of 889 and 893 nm have a significant influence on it. (4) according to the model fitting accuracy, the selected optimal BOD inversion model is the partial least squares regression model, and the accuracy of the partial least squares model is verified to be good (R2=0.81). Based on the above test results, an inversion method based on partial least squares hyperspectral BOD parameters of water quality is proposed, which provides a new method for dynamic detection of water quality BOD parameters.
Key words：Hyperspectral; BOD; Model; Partial least squares method; Multiple regression
王洪伟，王 波，纪 童，徐 君，剧 锋，王彩玲. 基于高光谱的水体BOD含量模拟估算[J]. 光谱学与光谱分析, 2021, 41(03): 978-983.
WANG Hong-wei, WANG Bo, JI Tong, XU Jun, JU Feng, WANG Cai-ling. Simulation Estimation of BOD Content in Water Based on Hyperspectra. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2021, 41(03): 978-983.
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