Study On Long-term Character Of Suspended Sediments In Minjiang Estuary Based On MODIS

Suspended sediment content of water directly affects the water quality of the optical properties such as transparency and color, also affect the aquatic environment and changes erosion and deposition process in estuarine and coastal. Remote sensing can overcome the drawback of traditional methods of investigating suspended sediment, as slow speed, inefficiency, long period time, only getting discrete and small amounts of data in time and spatial distribution. Remote sensing is able to monitor the dynamic change and spatial distribution of suspended sediment concentration efficiently that it has great significance.In this paper, Minjiang Estuary as study area, firstly verify the model proposed by predecessors, and then related field data and water-leaving radiation in remote sensing images to establish inversion mode of suspended sediment; model inversion using the newly created suspended sediment concentration Minjiang River Estuary, and to make average data monthly, analysis changes in suspended sediment concentration monthly between 2002 and 2009 years and summary the mechanism affecting changes of suspended sediment content.The conclusions are as follows:1. Combined with the measured turbidity data and normalized water-leaving radiance ratio (nLw667/nLw488) of MODIS remote sensing image to build relationships, show that y= 0.618x2-5.720x+18.94 (which y is turbidity, x is nLw667/nLw488) has high precision of inversion, R2 reached 0.716, average relative error is 18%, the relative error is less than 0.3.2. Distribution of suspended sediment in Minjiang Estuary has obvious regional distribution and large seasonal variations. Basic law is that:due to the geographical characteristics of the Minjiang River Estuary, coastal concentration is high, and the changes is decrease from the shore to the central sea, coastal water has the higher the concentration of suspended sediment, concentration of suspended sediment in the central sea decrease. Seasonal changes in autumn and winter (December or so) reached the maximum concentration of suspended sediment. 3. Most of the sediment in water in Minjiang estuary and adjacent waters is from runoff water and sediment resuspension, is mainly affected and controled by surface runoff and comparison of ocean dynamics (wave, tidal and ocean currents) strength.