Others have been badly maintained or have simply silted up.

ECONOMIST: Small projects often give better returns

Sanmenxia was the nation's pride until its reservoir silted up.

ECONOMIST: China and opposition to dams

The site has been under excavation since the late nineteenth century, so that all of its surviving monuments have been unearthed and to some extent restored, though its ancient harbor, the Lion Port, has long been silted up, leaving Miletus marooned miles from the sea.

WSJ: 'Aladdin's Lamp'

Silted-up rivers must be expensively dredged before the dry season ends in May, or they will flood again with the first rains.

ECONOMIST: Honduras and Nicaragua