Monitoring of seasonally variability and movement of suspended sediment concentration along Thiruvananthapuram coast using OLI sensor

In the recent decades hydrologists, geologists, and stream ecologists have shown substantial interest in analyzing suspended sediments in water. Extracting information like suspended sediment concentration (SSC) in coastal waters is very important for assessment and monitoring of coastal settings and their effects on their ecology. This article demonstrates importance of Landsat 8 Operational Land Imager (OLI) for monitoring seasonal variation in SSC and movement (pre and post monsoon) along Thiruvananthapuram Coast in India. The data was converted into marine reflectance after correcting due atmospheric errors. SSC was extracted using spectral analysis data analysis. Movement of SSC was monitored using wave direction and significant wave height data. The results revealed that the SSC decreased rapidly with the increase in distance from the beach and depth of the seabed. Wave with higher frequency in deeper water caused sparely circulation of sediments and their concentration at the lower depth in high bathymetry. Thus, the suspended sediments were indirectly proportional to bathymetry and distance from the shoreline and directly proportion to wave direction and littoral current at off-shore. High concentration of sediments was found to be accumulated at shallow depth (

The Study of Environmental Characteristic by Coastal Engineering in Rock Coast

In order to study the evolvement of rock coastal in Hebei Province, the data was taken to study the evolved stations, such as relief maps, charts, remote sensing imagines and the field data of different areas from 1956 to 2007. With 3 S technology, it analyzed the evolvement processing and reasons of the rock coast by construction of coastal engineering in half century. The results were shown that it was changed strongly by the station from 1979 to 2007 when the station stopped the littoral current caused by coastal engineering such as Qinhuandgao Port and Shanhaiguan Shipyard. As the result, the section was deposited in the east of Qinhuangdao Port while eroded in the west. And the highest erosion speed was 2.49 m/a in the section from Xinkaihe River to South Mountain shipside. The angle was about 60°~80° from between middle bay and east bay. By the transport yield reduce of Tanghe River and Chituhe River, the coastline was eroded by NNE and ENE waves. Without the supply of sediment from the east bay and middle bay where were eroded seriously, the erosion speed was above 3.26 m/a, and the section was eroded fast with the speed of 3.67 m/a between Jinshan Mountain and Tiger Stone in west bay.

TRACING COASTAL SEDIMENT MOVEMENT BY NATURALLY RADIOACTIVE MINERALS

The process by which sediments are moved along the shore is known as littoral drift and it includes beach drifting and longshore drift (Johnson, 1919). Coarse material is moved along a foreshore in zig-zag paths under the influence of swash and backwash of the waves. The process of longshore drift is due to longshore currents set up within the breaker zone by breaking waves approaching the shoreline at an angle. Although the waves tend to become parallel to the coast as a result of refraction, they usually break at a slight angle to the shore with the result that a littoral current is induced and is effective in moving a mass of water (and the sediment placed in suspension by the breaking waves) slowly along the coast. It is this current combined with the agitating action of the breaking waves, that is the primary factor in causing movement of sand along a coastline. It is believed that the largest percentage of the littoral transport occurs shoreward of the breaking point of the waves .