East Siberian Sea runoff into the East Siberian Sea is relatively small at about 250 km/year that makes only 10% of the total runoff in all the Arctic seas of Russia. The largest contribution is from the Kolyma River at 132 km, followed by the Indigirka River at 59 km. Most runoff (90%) occurs in summer; it is concentrated near the coast, owing to the weak river currents, and therefore does not significantly affect the sea hydrology. The water exchange between the neighboring seas is as follows. The annual outflow to the Laptev Sea, Chukchi Sea and Arctic Ocean is 3,240, 6,600 and
Siberian Shelf Sea, and respectively subdivided into the Kara Shelf, the Laptov Shelf and the East Siberian Shelf. Eastwards it merges into the Chukchi Shelf (of the Chukchi Sea) shared by Eurasia and North America (i.e., by Russia and the United States). Westwards it merges into the Barents Shelf of the Barents Sea. Also, the New Siberian Islands and the New Siberian Rift Basin define the 'New Siberian Shelf.' According to the split of the high Arctic by the Lomonosov mid-ocean ridge into the Eurasian Basin and Amerasian Basin, the Siberian Shelf is split between the Eurasian Shelf and the Amerasian Shelf.