河流水体悬浮物的反射光谱研究

发布时间：2018-03-09 08:33

本文选题：悬浮物　切入点：反射率　出处：《西南交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：利用遥感技术对水体水质进行监测的方法,是一种目前已经为人们所认识、接受的高科技监测方法。与传统以点代面的布设水质观测点的方法相比,该方法可以对大范围的水域做到快速有效的监测。但是,目前使用卫星数据由于几何分辨率和光谱分辨率的限制,对于河流水质的监测存在一些局限性,并且传统的利用卫星数据来反演水质参数的方法,很少考虑水深的影响,本文认为这是一个不足之处。考虑到一般卫星数据对河流水质监测的局限性,本文以成都市锦江为研究区,以悬浮物作为水质污染参数的研究对象,使用成像光谱仪来完成水质光谱数据的收集,探究了不同浓度的悬浮物和不同水体深度对水体光谱特征的影响。主要研究内容和研究成果如下：(1)悬浮物浓度数据和光谱数据的采集根据实验方案设定的水质采样点,实地进行水样的采集,并且在实验室完成悬浮物浓度的测量。本文创新性的提出了白板法来采集悬浮物水体的光谱数据,分别在不同悬浮物浓度和不同水体深度下采集水体中白板的光谱数据。(2)水体光谱数据的处理选取成像光谱仪影像上陶瓷白板上的十个点,通过均值化得到水体中白板在成像光谱仪全波上的反射率值,考虑到噪声的影响,最后选取的是400—900nm波段的反射率值。由于成像光谱仪的高光谱分辨率,白板反射率数据存在噪声干扰,进行数据的压缩,最后在400—900nmm波段上得到水体中不同浓度和深度白板平滑的反射率光谱曲线。(3)不同浓度下悬浮物的反射光谱特征随着悬浮物浓度的增大,水体中白板的反射都普遍减小,但是减幅不同；反射率曲线具有双峰性,当悬浮物浓度较低时,第一反射峰值在绿光波段,随着浓度的增大,第一反射峰值向红光波段移动,第二反射峰基本没有改变；在红外波段上,悬浮物浓度高的反射率较悬浮物浓度低的减小慢。(4)不同深度下悬浮物的反射光谱特征随着深度的增加,白板反射率值都逐渐减小；不同浓度的悬浮物水体,对深度的敏感程度不一致,高浓度最敏感,中浓度次之,低浓度较差；波段对深度的差异性,不同浓度的水体,在不同的波段上对深度的敏感程度不一致。(5)不同悬浮浓度和深度与反射率之间模型的建立分别基于单波段模型、波段比值模型和光谱反射率微分模型,进行了反射率与悬浮物浓度的相关性分析,确定了各模型的最敏感波段,根据敏感波段进行拟合,结果表明几种条件下二次项的拟合效果最好；同样的方法,在深度与反射率之间进行相关性分析,最后拟合深度与反射率的经验公式,结果表明：对于高浓度和中等浓度水体,幂拟合效果最好,低浓度水体线性拟合效果最好。
[Abstract]:The method of using remote sensing to monitor water quality is a kind of high-tech monitoring method which has been recognized and accepted by people at present. This method can be used for rapid and effective monitoring of a wide range of waters. However, due to the limitation of geometric resolution and spectral resolution of satellite data at present, there are some limitations in monitoring the water quality of rivers. And the traditional method of using satellite data to retrieve water quality parameters seldom considers the influence of water depth, which is considered to be a deficiency, considering the limitation of general satellite data on river water quality monitoring. In this paper, the Jinjiang River of Chengdu is taken as the research area, the suspended matter is taken as the research object of water pollution parameters, and the imaging spectrometer is used to complete the collection of water quality spectral data. The effects of different concentrations of suspended matter and different depth of water body on the spectral characteristics of water body were investigated. The main contents and results of the study were as follows: 1) the collection of suspended matter concentration data and spectral data according to the water quality sampling point set by the experimental scheme. Water samples were collected in the field, and the concentration of suspended matter was measured in the laboratory. In this paper, the white board method was proposed to collect the spectral data of the suspended water body. The processing of Spectral data of White Plate in Water body under different suspended matter concentration and different Water depth) 10 points on ceramic whiteboard image of imaging spectrometer were selected. The reflectivity of whiteboard on the whole wave of imaging spectrometer is obtained by means of mean value. Considering the effect of noise, the reflectivity value of 400-900nm band is selected finally. Because of the high spectral resolution of the imaging spectrometer, The whiteboard reflectivity data has the noise interference, carries on the data compression, Finally, the reflectance spectral characteristics of the suspended solids with different concentrations and depth were obtained at the wavelength of 400-900nmm) with the increase of the concentration of the suspended solids, the reflectance of the whiteboards in the water decreased generally with the increase of the concentration of the suspended solids. But the amplitude is different, the reflectivity curve has bimodal property, when the concentration of suspended matter is low, the first reflection peak is in the green wave band, with the increase of concentration, the first reflection peak moves to the red light band, and the second reflection peak basically remains unchanged. In the infrared band, the reflectance of the suspended substance with high concentration is lower than that of the suspended substance. 4) the reflectance of the suspended substance decreases with the increase of the depth, and the reflectivity of the white board decreases with the increase of the depth, and the reflectivity of the suspended substance with different concentrations decreases with the increase of the depth. The sensitivity to depth is not consistent, high concentration is the most sensitive, medium concentration is second, low concentration is poor, the difference of wave band to depth, different concentration of water, The models of different levitation concentration and depth and reflectivity are based on single band model, band ratio model and spectral reflectivity differential model, respectively. The correlation analysis between reflectivity and concentration of suspended solids is carried out, and the most sensitive bands of each model are determined. The results show that the fitting effect of quadratic terms is the best under several conditions. The correlation between depth and reflectivity is analyzed, and the empirical formula of depth and reflectivity is fitted. The results show that power fitting is the best for high and medium concentration water, and linear fitting is best for low concentration water.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X87;X832

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