FIGURE 5.5 Variation of sediment load with basin area for the seven topographic categories of river basins listed in Table 1 (Milliman and Syvitski, 1992). For all river types the correlation is strong (r2 ranging from 0.70 to 0.82). Note that only 13 rivers deviate by more than one standard deviation from the computed means.

the Alps are tributaries to the Danube, the largest river in Europe. The Rhine is the only large alpine river that drains north to the sea, but most of its sediment load is trapped in Lake Constance; upstream of Lake Constance, the river has a sediment yield consistent with other alpine rivers, but downstream of the lake, its yield is similar to a lowland/coastal plain river (Holeman, 1968).

USSR and Asia Minor

The large rivers of the former Soviet Union draining north to the Arctic Sea (Ob, Lena, and Yenesi) are generally considered to have anomalously low sediment yields (see Milliman and Meade, 1983). However, their sediment yields and those of other Russian rivers correlate well with other upland and lowland rivers throughout the world (Figure 5.6; Table 1, Milliman and Syvitski, 1992). Russian and Ukrainian rivers draining south into the Black Sea are considered lowland rivers, with correspondingly low sediment loads.

Although poorly documented in western literature, the rivers draining the Caucasus Mountains and the Anatolian and Taurus mountains in Turkey have high sediment yields, which is to be expected from rivers draining the same collision orogen as the Alps. Before dam construction in the 1950s, the three largest Turkish rivers emptying into the Black Sea discharged an estimated 50 mt of sediment annually (Hay, 1987). Collectively, in fact, the rivers draining northern Turkey and the western Caucasus Mountains may contribute more sediment to the Black Sea than the Danube and southwestern Russian and Ukranian rivers.

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