Suspended sediment load

A river s sediment load consists of both suspended sediment and bed load. The latter, which moves by traction or saltation along the river bed, is generally assumed to represent 10% (or less) of the total sediment load. Suspended sediment includes both wash load (mostly clay and silt that is more or less continually in suspension) and bed material load (which is suspended only during higher flow) bed material includes coarse silt and sand that may move as bed load during lower flow. A sediment-rating... 

Rivers transport suspended sediments derived from the disintegration of basin surface layers. With reduced velocity, sediment is deposited in the river channel. The finest material is carried to the sea. It has been estimated that the average mechanical denudation rate for continents is 0.056 mm year (35). This is based on a total suspended load of 13.5 x 10 metric tons year (S). Presently, about two-thirds of the world s total suspended sediment load derives from Southern Asia and large Pacific Islands. Berner has estimated the increase in sediment loss in the U.S. and world since prehuman times to be approximately 200% (35). Current estimated erosion rate from the major land forms is provided in Table I. The relatively recent construction of large sediment trapping dams that normally caused sediment to be deposited in river valleys or transported to the ocean has drastically reduced sediment yields in great rivers. 

The material transported by rivers consists of dissolved ions (dissolved load), sediment suspended in the flow (suspended load), and sediment transported along the bed of the river (bedload). The total load and the proportion of the load represented by these phases varies widely among rivers in different environments. In particular, climate, topography, and erosion influence the amount and composition of riverine sediment loads. 

Sediment Load in the Lower Ebro 5.2.1 Suspended Load... 

Fig. 7 Duration curves for (a) runoff, (b) suspended sediment load and (c) bedload in the lower Ebro River for the period 2002-2008...

Walling DE, Fang D (2003) Recent trends in the suspended sediment loads of the world s rivers. Glob Planet Change 39 111-126... 

River transport of clay minerals into the ocean is spatially and temporally variable. The global annual suspended load of river sediment into coastal waters currently averages 12.6 X 10 ton. This flux is approximately 10% less than was delivered before humans began damming rivers. (One notable exception is the Mississippi River, whose sediment load has increased due to very high rates of soil erosion. The riverine sediments deposited in the mouth of the Mississippi River form one of the world s largest deltas.)... 

Loizeau JL, Dominik J (2000) Evolution of the upper Rhone river discharge and suspended sediment load during the last 80 years and some implications for Lake Geneva. Aquat Sci 62(l) 54-67... 

The availability of other sample media at a drainage site has been briefly mentioned previously. The dirty water filters with the >45 im suspended sediment captured on the filter discs could be very useful in studies of the suspended-sediment load. The Fe and Mn coatings on pebbles and other chemical precipitates (e.g., insoluble Fe hydroxides) could also be collected as these are known to have good scavenging properties for certain trace elements. 

Table 4 Average water runoff and suspended sediment load of the rivers entering the Black Sea along the northeastern coast within Russia [21,22]...

Present-day average data on river water runoff and suspended sediment load will be presented below. This information is based mainly on [19,21,22] and own investigations of the authors of this chapter. 

The overall amounts of water runoff and suspended sediment load into the Black Sea from rivers within Russia are about 6.4 km3 year-1 and 1.6 x 106 tyear-1 respectively. 

The overall amount of the suspended sediment load of the considered rivers is significant and equal to 18.6 x 106 tyear 1 (Table 5). At present the... 

On the coast of Bulgaria the majority of the rivers are small or very small. The largest river is the Kamchea with present-day average annual water runoff of 0.6 km3 and suspended sediment load of 4.6 x 106 tyear-1. 

River and parts of the coast Drainage area, 103 km2 Specific water discharge, 1 s1knr2 Water runoff, km3 year-1 Suspended sediment load, 103 t year-1... 

Water runoff and suspended sediment load of the Dniester and Dnieper rivers also decreased after construction of reservoirs (Table 8) (see Sects 6.2 and 6.3). 

River Drainage area, 103 km2 Annual water discharge, 3 -1 m s 1 Specific water discharge, 1 s-1 km-2 Water runoff, km3year-1 Suspended sediment load, 106 tyear-1 Refs. 

Before the river flow regulation in the first part of the 20th century total water runoff and suspended sediment load of all the rivers in this coastal sector equalled about 265 km3 year-1 and 60.3 x 106 tyear 1 correspondingly. Combined decrease in the average water runoff comprised only about 2 km3 year-1, which is less than 1%. Decrease in the suspended sediment load of the rivers is more significant - 19 x 106 lyear 1 that forms 31%. 

The total water runoff of the small mountain rivers of Crimea (Ukraine) does not exceed 0.3 km3 year-1. Their suspended sediment load is about 132 x 106 tyear-1 (Table 9). 

Results of the calculation of the river water and sediment contribution to the Black Sea are given in Table 10. Total drainage area of all the considered rivers approximately equals 1.8 x 106 km2. At present, values of the water runoff and suspended sediment load of all the rivers are equal to 354.5 km3 year-1 and 76.2 x 106 tyear-1 correspondingly. 

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