A Large Alluvial Fan, Southern Gansu, China
1 April 2008

Note: The area of coverage in this SPOT-5 image is approximately 62 km x 62 km.
The reduced resolution image on display has undergone compression and so does not represent the true resolution of the original satellite image.

From the south to the north, the lower slopes of the Yemu Shan are replaced by a large alluvial fan and the dry plain of Gansu. The 60 km by 43 km alluvial fan has been built by a number of braided channels radiating out of the mountains. The snow-spattered steep edge of the mountains is heavily dissected, even scarp-like in places. A small lake high in the mountains drains through a gorge to the braided channels in the centre of the fan and an irrigation system along its eastern boundary. A fringe of low vegetation surrounds the toe of the fan, presumably because of moisture reaching the area via both channel flow and subsurface seepage. Agricultural fields cluster where the irrigation system emerges from the fan. Several of the channels continue beyond the fan, some ending in small ponds.