Tsiribihina River, Madagascar

Astronauts aboard the International Space Station took this image of muddy floodwaters and distributary channels in the northern sector of the Tsiribihina River delta on Madagascar's west coast. Delta distributaries have two morphologies, large and relatively straight, and the small, highly contorted channels between. Brown sediment from recent heavy rains reaches the sea where it is swept slowly north by local ocean currents (image lower left), with clearer blue water visible lower right. Over thousands of years sediment supplied by the river is shaped by waves along the shoreline into beach ridges--which appear as numerous parallel lines (image lower center and image right). Each line represents a prior coastline on this geologically fast-changing coast, with the oldest coastline lying furthest inland.

Four cyclones have hit Madagascar already by mid April, 2015. Heavier floods than those seen here followed a mid-January storm and affected not only the 50 km (31 mi) shoreline of the delta but also the lower 75 km (47 mi) of the river.
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This service is provided by the International Space Station program and the JSC Earth Science & Remote Sensing Unit, ARES Division, Exploration Integration Science Directorate.
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