CN106940290A - Reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data - Google Patents

Abstract

The invention discloses a kind of reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data; appraising model is established according to spectral reflectivity wavelength derivative and water body sample actual measurement ammonia-nitrogen content; and then the estimation of ammonia-nitrogen content is carried out according to appraising model; quickly obtain a high-precision estimation result; be conducive to deepening the environmental problem understanding of reservoir area eucalyptus, science and technology support and decision-making foundation are provided for protection water quality ecological safety, sustainable development.

Description

Reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data

Technical field

The present invention relates to water quality ecological security technology area, and in particular to a kind of reservoir water body ammonia based on high-spectral data Nitrogen content evaluation method.

Background technology

Eucalyptus is one of world-renowned three big quick growing species of trees, is sub- hot aithullium, originates in Australia.Due to eucalyptus In industrial applications such as papermaking, wood-based plate, buildings extensively, current Guangdong eucalyptus cultivated area is close to 3,000,000 hm².Fast-growing Eucalyptus Stand Ammonia nitrogen fertilising number of dropouts is more much bigger than other broad-leaf forests, causes the lake storehouse drinking water source protection zone water pollution in eucalyptus forest zone tight Weight.

The more concern eucalyptus plantation atmosphere pollution purification of conventional research, liquid manure utilize with Nutrient Cycling, water balance, Bio-diversity etc., pays close attention to inadequate to Eucalypt plantation ecosystem water quality negative effect.At present for greatly developing eucalyptus people Work woods, academia has dispute, and its bone of contention is the ecological environment problem of eucalyptus.For example, Guangdong west of Guangdong Province Yuexi Hedi Reservoir Across the Guangdong province's (longitude and latitude of osmanthus two in ground：21 ° of 42.561 ' -21 ° of 53.349 ' N, 110 ° of 16.859 ' -110 ° of 23.406 ' E), away from Zhanjiang City 75 kilometers, 122 square kilometres of reservoir surface area is one of big reservoir in Guangdong three, is the important water source in Zhanjiang City.It is big due to Eucalyptus Stand Amount is developed, and Reservoir Water Quality occurred in that the trend of being decreased obviously (wherein eucalyptus plantation is one of six big pollution sources), eucalyptus people in recent years Work woods water quality ecological problem has turned into one of common focus of attention of various circles of society in the sustainable development of Zhanjiang.

The content of the invention

In view of the shortcomings of the prior art, it is an object of the invention to provide a kind of reservoir water body ammonia based on high-spectral data Nitrogen content evaluation method, to improve the efficiency and precision of the monitoring of reservoir water body ammonia-nitrogen content.

In order to realize the above object the technical solution adopted by the present invention is as follows：

A kind of reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data, including step：

Live water spectral measurement and water body sampling are carried out in reservoir to be measured using field spectroradiometer, record water body is in each ripple The reflectivity of strong point simultaneously collects some groups of water samples；

The measurement of ammonia-nitrogen content is carried out to the water sample of collection；

Asked according to following derivatives and calculate the derivative that formula calculates each wavelength of spectral reflectivity；

R_i'=R_i+1-R_i

In formula, R represents the spectral reflectivity of field spectroradiometer measurement, and i is wavelength, and unit is nm；

N number of sample is randomly choosed from the water sample sample of collection, is contained using spectral reflectivity derivative and reservoir water body ammonia nitrogen Amount carries out Pearson correlation analysis, obtains the coefficient correlation P of each wavelength derivative of spectral reflectivity and ammonia-nitrogen content_i：

Wherein, P_iFor coefficient correlation, i is wavelength, R_i' it is each wavelength derivative of spectral reflectivity, y contains for reservoir water body ammonia nitrogen Data are measured, N is number of samples；

Choose coefficient correlation P_iCorresponding spectral reflectivity wavelength derivative and ammonia-nitrogen content during maximum absolute value, carry out shape Such as y=ax²+ bx+c quadratic function fitting, obtains reservoir water body ammonia-nitrogen content appraising model, wherein dependent variable y contains for ammonia nitrogen Amount, independent variable x is spectral reflectivity wavelength derivative；

The ammonia-nitrogen content of reservoir water body to be measured is estimated according to the reservoir water body ammonia-nitrogen content appraising model.

Reservoir water body ammonia-nitrogen content evaluation method of the invention based on high-spectral data, according to spectral reflectivity wavelength derivative Appraising model is established with water body sample actual measurement ammonia-nitrogen content, and then the estimation of ammonia-nitrogen content is carried out according to appraising model, quickly Obtain a high-precision estimation result, be conducive to deepen reservoir area eucalyptus environmental problem understanding, for protection water quality ecological safety, Sustainable development provides science and technology support and decision-making foundation.

Brief description of the drawings

Fig. 1 is the geographical position schematic diagram of Hedi Reservoir；

Fig. 2 is the geographical position schematic diagram after Hedi Reservoir amplifies；

Fig. 3 is the schematic diagram of Hedi Reservoir locus and water sampling point；

Fig. 4 is the schematic flow sheet of the reservoir water body ammonia-nitrogen content evaluation method of the invention based on high-spectral data；

Fig. 5 sets up schematic diagram for reservoir water body ammonia-nitrogen content appraising model；

Fig. 6 is the schematic diagram verified to the precision of reservoir water body ammonia-nitrogen content appraising model.

Embodiment

With reference to embodiment, the present invention is further illustrated.

As Figure 1-3, Hedi Reservoir is located in Lezhou Peninsula the north, and the He Chun towns in 14 kilometers of west of a city north, reservoir area leap is wide The Luchuan of western Zhuang autonomous region, the county of Bobai two, in nine continent Jiang Zhongyou, 1440 square kilometres of catchment area, aggregate storage capacity 11.51 hundred million Cubic meter, is based on irrigation, with reference to the large reservoir of the comprehensive utilizations such as flood control, generating and shipping.Designed irrigation area 2,000,000 Mu, 1,270,000 mu of effective irrigation area.Hedi Reservoir is carry-over storage, the billion cubic meter of aggregate storage capacity 11.875, wherein adjusting big vast storehouse Hold 3.115 billion cubic meters, the billion cubic meter of utilizable capacity 5.36, the billion cubic meter of minimum capacity of a reservoir 3.4.Hedi Reservoir irrigated area canal system from north to More than half Lezhou Peninsula is run through in south.Entitled " the main river in Lezhou Peninsula youth canal " 76 kilometers of the total length of general main canal, design is most greater than water The cubic meters per second of ability 120.There are Dong Haihe, Xi Haihe, eastern canal, western canal, 5, tetrad trunk canal in big trunk canal, 195 is grown altogether public In；155, trunk canal, it is long 1164 kilometers；1467, branch canal, it is long 4041 kilometers.

Using Hedi Reservoir as reservoir to be measured, as shown in figure 4, the detailed process of the present embodiment is as follows.

Step 101, using field spectroradiometer, preferably by ASD field spectroradiometers, according to mensuration on the water surface, Water spectral measurement and water body sampling are carried out across the Hedi Reservoir reservoir area of Guangdong, the province of Guangxi two, 36, sample is obtained altogether.

Step 102, the water sample of collection are fitted into water sample bottle, it is to avoid sunlight irradiates and sent laboratory back within 24 hours Row ammonia-nitrogen content is determined, and measuring method is Na's reagent.

Step 103, the derivative for calculating each wavelength of calculating shown in formula 1 is sought according to derivative；

R_i'=R_i+1-R_i (1)

In formula, R is the spectral reflectivity of ASD field spectroradiometers measurement, and i is wavelength, and unit is nm；

Step 104, according to total number of samples (36 samples), 26 samples of random selection carry out ammonia-nitrogen content inverse models Set up, remaining 10 samples are used for precision test.Obtained spectral reflectivity derivative data and water is calculated using formula (1) The measurement data of storehouse water body ammonia-nitrogen content, carries out Pearson correlation analysis and obtains each wavelength derivative of spectral reflectivity and ammonia nitrogen The coefficient correlation P of content_i, shown in Pearson Related Computational Methods such as formula (2).

Wherein, P_iFor coefficient correlation, i wavelength, R_i' it is each wavelength derivative of spectral reflectivity, y is reservoir water body ammonia-nitrogen content Data, N is number of samples.

Step 105, selection coefficient correlation P_iCorresponding the spectral reflectivity wavelength derivative and ammonia nitrogen of maximum absolute value contain Data are measured, shape such as y=ax is carried out using the Regression Function of SPSS softwares²+ bx+c quadratic function fitting (wherein dependent variable Y is ammonia-nitrogen content data, and independent variable x is spectral reflectivity wavelength derivative), finally try to achieve parameter a=26041023.4161, b= 879.9943rd, the c=0.0407 coefficients of determination are 0.602.Establish reservoir water body ammonia-nitrogen content appraising model y= 26041023.4161x²+ 879.9943x+0.0407, relation such as Fig. 5 institutes between independent variable x and dependent variable y and appraising model Show.

Step s106, by spectral reflectivity wavelength derivative substitution appraising model can rapidly and accurately estimate the ammonia of water-outlet body Nitrogen content.

In order to verify the precision of above-mentioned appraising model, using the spectral reflectivity wavelength derivative data of remaining 10 samples as Independent variable is substituted into above-mentioned reservoir water body ammonia-nitrogen content appraising model respectively can try to achieve 10 ammonia-nitrogen content digital simulation values respectively, Based on 10 ammonia-nitrogen content analogues value and its measure actual value, as shown in fig. 6, with root-mean-square error RMSE and average relative error MRE carrys out the precision of characterization model, and RMSE and MRE computational methods are respectively as shown in formula (3), (4)；

In formula, RMSE is root-mean-square error, and MRE is average relative error, and y is ammonia-nitrogen content actual value, and y ' contains for ammonia nitrogen The analogue value is measured, n is number of samples.

To sum up, high-spectral data reservoir water body ammonia-nitrogen content modeling accuracy and simulation precision are based on by analysis, finally built The reservoir water body ammonia nitrogen inversion method based on high-spectral data is found.

Above-listed detailed description is illustrating for possible embodiments of the present invention, and the embodiment simultaneously is not used to limit this hair Bright the scope of the claims, all equivalence enforcements or change without departing from carried out by the present invention are intended to be limited solely by the scope of the claims of this case.

Claims (5)

1. a kind of reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data, it is characterised in that including step：

Live water spectral measurement and water body sampling are carried out in reservoir to be measured using field spectroradiometer, record water body is at each wavelength Reflectivity and collect some groups of water samples；

The measurement of ammonia-nitrogen content is carried out to the water sample of collection；

Asked according to following derivatives and calculate the derivative that formula calculates each wavelength of spectral reflectivity；

R_i'=R_i+1-R_i

In formula, R represents the spectral reflectivity of field spectroradiometer measurement, and i is wavelength, and unit is nm；

N number of sample is randomly choosed from the water sample sample of collection, is entered using spectral reflectivity derivative and reservoir water body ammonia-nitrogen content Row Pearson correlation analysis, obtains the coefficient correlation P of each wavelength derivative of spectral reflectivity and ammonia-nitrogen content_i：

$P_i=\frac{{{\mathrm{\ΣR}}_i}^{\′}y-\frac{{{\mathrm{\ΣR}}_i}^{\′}\mathrm{\Σ}y}{N}}{\sqrt{({{\mathrm{\ΣR}}_i}^{\′2}-\frac{{\left({{\mathrm{\ΣR}}_i}^{\′}\right)}^2}{N})\left(\sqrt{({\mathrm{\Σy}}^2-\frac{{\left(\mathrm{\Σ}y\right)}^2}{N})}\right)}}$

Wherein, P_iFor coefficient correlation, i is wavelength, R_i' it is each wavelength derivative of spectral reflectivity, y is reservoir water body ammonia-nitrogen content number According to N is number of samples；

Choose coefficient correlation P_iCorresponding spectral reflectivity wavelength derivative and ammonia-nitrogen content during maximum absolute value, carry out shape such as y= ax²+ bx+c quadratic function fitting, obtains reservoir water body ammonia-nitrogen content appraising model, and wherein dependent variable y is ammonia-nitrogen content, from Variable x is spectral reflectivity wavelength derivative；

The ammonia-nitrogen content of reservoir water body to be measured is estimated according to the reservoir water body ammonia-nitrogen content appraising model.

2. the reservoir water body ammonia-nitrogen content evaluation method according to claim 1 based on high-spectral data, it is characterised in that

36 groups of water samples are collected, and randomly choose 26 groups of water samples therein and carry out building for the reservoir water body ammonia-nitrogen content appraising model Vertical, it is 0.602, the water of foundation finally to try to achieve parameter a=26041023.4161, b=879.9943, c=0.0407 coefficient of determination Storehouse water body ammonia-nitrogen content appraising model is y=26041023.4161x²+879.9943x+0.0407。

3. the reservoir water body ammonia-nitrogen content evaluation method according to claim 2 based on high-spectral data, it is characterised in that Also include step：

The spectral reflectivity wavelength derivative of n sample outside N number of sample is substituted into the reservoir water body as independent variable respectively In ammonia-nitrogen content appraising model, ammonia-nitrogen content analogue value y ' is obtained, it is homogeneous with root-mean-square error RMSE peace with reference to measured value y Carry out the precision of characterization model to error MRE, RMSE and MRE computational methods are shown below respectively；

$RMSE=\sqrt{\frac{\underset{j=1}{\overset{n}{\Σ}}{(y_j-y_j^{\′})}^2}{n}}$

$MRE=\frac{\underset{j=1}{\overset{n}{\Σ}}\left|\frac{y_j-{y_j}^{\′}}{y_j}\right|}{n}\×100\%.$

4. the reservoir water body ammonia-nitrogen content evaluation method according to claim 3 based on high-spectral data, it is characterised in that

The fitting of the quadratic function is carried out using the Regression Function of statistical analysis software.

5. the reservoir water body ammonia-nitrogen content evaluation method based on high-spectral data according to claim 1 or 2 or 3 or 4, its It is characterised by,

The water sample of collection is fitted into water sample bottle, it is to avoid sunlight, which irradiates and sent laboratory back within 24 hours, carries out ammonia-nitrogen content survey Amount, measuring method is Na's reagent.