# Space-Ground Remote Sensor Network for Monitoring Suspended Sediments in the Yellow River Basin
## 3 Results and Analysis
### Hyperspectral Monitoring of Water and Sediment in the Qingshui River
Both the HJ2A and HJ2B remote sensing images in the figure are false-color composites and have the same spatial resolution of 16 m. The color difference descriptions are the same as those in Figure 7.  
Figure 6: Different water colors of the Yellow River with varying SSC at the Xiaolangdi reservoir. (**a**) Clear water released from the Xiaolangdi reservoir during the primary water and sediment regulation phase before the flood in 2023. (Xinhua News, 12 July 2023 16:43, [[https://www.news.cn/2023-07/12/c_1129745575.htm](https://www.news.cn/2023-07/12/c_1129745575.htm)]([https://www.news.cn/2023-07/12/c_1129745575.htm](https://www.news.cn/2023-07/12/c_1129745575.htm)), accessed on 5 June 2024); (**b**) Sediment was discharged from the Xiaolangdi reservoir on the Yellow River in Ijiyuan, Henan on 7 July 2023. (Pengpai News, 11 July 2023 17:48, [[https://www.thepaper.cn/newsDetail_forward_23809045](https://www.thepaper.cn/newsDetail_forward_23809045)]([https://www.thepaper.cn/newsDetail_forward_23809045](https://www.thepaper.cn/newsDetail_forward_23809045)), accessed on 5 June 2024); (**c**) Xiaolangdi flood discharge on 2 October 2021. (Henan Daily, [[https://baijihao.baidu.com/s?id=1713561072209768428&wfr=spider&for=pc](https://baijihao.baidu.com/s?id=1713561072209768428&wfr=spider&for=pc)]([https://baijihao.baidu.com/s?id=1713561072209768428&wfr=spider&for=pc](https://baijihao.baidu.com/s?id=1713561072209768428&wfr=spider&for=pc)), accessed on 5 June 2024). Figure 7: The changes in the water and sediment status of the Xiaolangdi reservoir and downstream areas during the water and sediment regulation period of the Yellow River before the flood in 2023 (from 21 June 2023 to 11 July 2023). Except for Figure (**f**), which is a true-color composite image, all other figures are false-color composites (the false-color image is composed of the NIR, Red, and Green bands; in the false-color image, vegetation areas are shown in red, clear water areas in dark color, and water bodies with high sediment content in brighter colors; the same applies to the following figures). Figure 8 displays the changes in water and sediment at the Yellow River estuary during the same period. The maximum flow at the Lijin hydrological station was 3730 m\({}^{3}\)/s on 3 July 2023. Under the influence of the high tide, the extent of the turbid water mass at the Yellow River estuary was largest on 5 July. The SSC at the Lijin hydrological station reached a maximum of 11.80 g/L on 11 July at 8 a.m., but the impact was not significant on the same day, as shown in Figure 8d. These results highlight the complexity of water volume and sediment concentration affecting the estuarine water body. According to the method proposed by [PERSON] et al. (2014) [PERSON] et al. (2014) for Chinese environmental monitoring satellites, the SSC was quantitatively retrieved for the satellite images (Figures 7 and 8) over the Xiaolangdi reservoir and the Yellow River estuary. The temporal and spatial changes in SSC are shown in Figure 9, and a highly dynamic range in SSC from several milligrams per liter to hundreds of grams per liter was also captured by satellite remote sensing over the Yellow River, as captured by an in situ spectral station over the Qingshui River (Figure 5).