Estimation of Sediment Concentration in the Pearl River Estuary Based on Remote Sensing

Author(s):  
Bowen Cao ◽  
Xiankun Yang ◽  
Junliang Qiu ◽  
Xuetong Xie ◽  
Haitao Li

<p>The estimation of Suspended Sediment Concentration (SSC) on the surface of the Pearl River is of great significance to the management of water and soil erosion and water quality in the Pearl River. Previous studies lack of measured reflectance data and enough field samples and the distribution of sediment-concentration field samples were uneven. In response to the above problems, we combined the sediment concentration data (proceed by filtered weighing method) collected on the spot, high-precision ground measured spectral data (obtained by ASD) with multi-source remote sensing satellite images (MODIS and Sentinel-2), employing simple linear regression model (single logarithmic transformation) and neural network learning algorithm to fit the relationship model between SSC and surface reflectance (Surface Reflectance, SR). The preliminary results showed that SSC and the surface SR based on the red band (wavelength=665 nm) had a stable correlation (R2>0.83), and the red band of Sentinel 2 was appropriate for the estimation of SSC. Compared with previous studies, this study synthesized higher-precision spectrum measured data and higher-resolution remote sensing satellite data to improve the estimation accuracy of SSC. In addition, based on the SSC model under study, we will couple long-time series of satellite data to explore the spatiotemporal variation characteristics of SSC in the Pearl River, so as to provide a reference for soil erosion monitoring and water resources management in the Pearl River Basin.</p>

Author(s):  
Gordana Kaplan ◽  
Ugur Avdan

Wetlands benefits can be summarized but are not limited to their ability to store floodwaters and improve water quality, providing habitats for wildlife and supporting biodiversity, as well as aesthetic values. Over the past few decades, remote sensing and geographical information technologies has proven to be a useful and frequent applications in monitoring and mapping wetlands. Combining both optical and microwave satellite data can give significant information about the biophysical characteristics of wetlands and wetlands` vegetation. Also, fusing data from different sensors, such as radar and optical remote sensing data, can increase the wetland classification accuracy. In this paper we investigate the ability of fusion two fine spatial resolution satellite data, Sentinel-2 and the Synthetic Aperture Radar Satellite, Sentinel-1, for mapping wetlands. As a study area in this paper, Balikdami wetland located in the Anatolian part of Turkey has been selected. Both Sentinel-1 and Sentinel-2 images require pre-processing before their use. After the pre-processing, several vegetation indices calculated from the Sentinel-2 bands were included in the data set. Furthermore, an object-based classification was performed. For the accuracy assessment of the obtained results, number of random points were added over the study area. In addition, the results were compared with data from Unmanned Aerial Vehicle collected on the same data of the overpass of the Sentinel-2, and three days before the overpass of Sentinel-1 satellite. The accuracy assessment showed that the results significant and satisfying in the wetland classification using both multispectral and microwave data. The statistical results of the fusion of the optical and radar data showed high wetland mapping accuracy, with an overall classification accuracy of approximately 90% in the object-based classification. Compared with the high resolution UAV data, the classification results give promising results for mapping and monitoring not just wetlands, but also the sub-classes of the study area. For future research, multi-temporal image use and terrain data collection are recommended.


2014 ◽  
Vol 17 (3) ◽  
pp. 271-279 ◽  
Author(s):  
Haibin Ye ◽  
Chuqun Chen ◽  
Shilin Tang ◽  
Liqiao Tian ◽  
Zhaohua Sun ◽  
...  

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