But the ideology that produced al Qaeda isn't a rivulet in contemporary Muslim thought.

CENTERFORSECURITYPOLICY: Speaking truth to Muslim power

Mr McTiernan began using irrigation water from a rivulet running out of the Bighorn Mountains called Smith Creek.

ECONOMIST: Western water rights

But, requesting anonymity, some customs field staff told the BBC that at night, smugglers fix ropes at both sides of a rivulet that separates the Nepal-Tibet border.

BBC: 'Safe passage' for wildlife traffickers