The paper gives a quantitative analysis on soil erosion in Shanchonghe watershed. The quantitative analysis is based on a revised universal soil loss equation (RUSLE), supported by geographic information system (GIS) and remote sensing (RS) technology, and according to the landform, rainfall, vegetation data, etc., in Shanchonghe watershed, which are obtained from interpreted data of Shanchonghe watershed RS image and it’s statistics data. The results showed that the annual soil erosion modulus in Shanchonghe watershed is 19.05 t / (hm<sup>2</sup>*a), the annual soil erosion amount is 2744.23 t/a. The soil erosion spatial distribution is very different. These areas have strong soil erosion, which height is more than 2000 meters above sea level, or which slope is bigger than 25 degree, or bare surfaces, or sloping farmlands. These are the focus areas of governance of soil erosion in Shanchonghe watershed. The study provides scientific basis to water and soil conservation work in Shanchonghe watershed.
Remote sensing has widely been used to study suspended sediment distributions due to its synoptic and repetitive coverage. Using previous <i>in situ</i> data and Landsat imagery, we estimate suspended sediment concentrations (SSC) in order to understand the transport and distribution of suspended sediments in the Nanhui nearshore area, China. During an ebb tide period, the area with the maximum turbidity was observed along the southern Nanhui nearshore area and the maximum SSC value was 1.916g/l. During a flood tide period, the area with the maximum turbidity moved northwards and the maximum SSC value was 1.400 g/l. The northern Nanhui nearshore area suffered from the strong current discharge from the South Passage, its eastern area was affected by wind waves, and its southern area was influenced by the tidal currents from the Hangzhou Bay. These processes were responsible for the southern Nanhui nearshore area
extending southeastwards and sediments in the northern Nanhui nearshore area.
Spatial and temporal distributions of suspended sediment concentration (SSC) are greatly important for analyzing the
deposition and erosion variety of estuaries and evaluating the fluxes from river to sea. A model based on data in situ
measurements for estimating concentration of the suspended sediment with MODIS band 2 images are developed by
taking Yangtze River estuary as an experimental site in this study. Numerous field spectral measurements are carried out
in the Yangtze River estuary, and SSC are obtained concurrently. By analyzing the remote sensing reflectance (Rrs) and
SSC, we observed that Rrs increases with SSC and their correlation coefficient is beyond 0.8 at near-infrared
wavelengths (750-900nm). A linear relationship was established between SSC and Rrs at 858.5nm wavelength (the
middle point of 841-876nm wavelength). Compared to MODIS band 15, 16, 17 (resolution of 1km) data, the MODIS
band 2 (resolution of 250m) data is suitable to detect the horizontal distribution of suspended sediment in narrow
estuaries because of relatively high spatial resolution. The linear function is applied to corrected MODIS Terra band 2
data. As a result, the horizontal distribution of SSC is retrieved in the Yangtze River estuary. This study demonstrates
MODIS band 2 (250m) data provides data well suited for the study of suspended sediment in dynamic estuarine waters.