Prediction of Tidal Flat Sediment Moisture Content Based on Wavelet Transform
LI Xue-ying1, 2, LI Zong-min3*, CHEN Guang-yuan4, QIU Hui-min2, HOU Guang-li2, FAN Ping-ping2*
1. School of Geosciences, China University of Petroleum (Huadong), Qingdao 266580, China
2. Institute of Oceanographic Instrumentation, Qilu University of Technology (Shandong Academy of Sciences), Qingdao 266061, China
3. College of Computer Science and Technology, China University of Petroleum (Huadong), Qingdao 266580, China
4. College of Ocean Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
Abstract：The distribution of water in flat tidal sediments will change greatly in space and time, and the changes will lead to the changes of biogenic elements in sediments. Therefore, the tidal flat sediment water content data are monitored in real time, accurately and quickly, which is of great significance to understanding the tidal flat characteristics, grasp the information of tidal flat biogenic elements, and develop tidal flat resources. This paper collected 115 samples of intertidal sediments from Dongdayang village, Qingdao city. The visible near-infrared spectra and moisture content of fresh samples, air-dried for 4 weeks and 8 weeks were measured. The db10 and sym6 wavelet basis were used to transform the original spectrum, and partial least squares regression was used to establish the tidal flat sediment moisture content model. The low-frequency information An and high-frequency information Dn(n=1, 2, …, 10) of the original spectrum were obtained by 10 order wavelet transform. S- Dn was calculated by the difference between the original spectrum S and Dn. The moisture content models were established using An, Dn and S- Dn, respectively, and the results were analyzed. The original spectrum model’s R2P, RMSEP and RPD were 0.841, 2.767 and 2.481. By analysing low-frequency and high-frequency information, after db10 wavelet basis transforms, the useless information was mainly concentrated in D3 and D4, and the accuracy of the moisture content model established by removing D3 and D4 was significantly improved, R2P was 0.878, RMSEP was 2.501, RPD was 2.749. Through the analysis of sym6 wavelet basis transform, the useless information was mainly concentrated in D5 and D9, the R2P, RMSEP and RPD by removing D5 and D9 were 0.87, 2.475 and 2.768. Therefore, by analyzing the low-frequency and high-frequency information using wavelet transform, the interference information of sediment moisture content can be effectively found, and the feature information can be extracted. The more accurate the tidal flat sediment moisture content model is established, it provides a theoretical basis for real-time and dynamic monitoring of tidal flat sediment moisture content.
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