Mr Khan says that the effect has not only been to wipe out this year's crops, but because of damage to the irrigation network, next season's crops will be lost too.

ECONOMIST: Blighted Pakistan

The problem is compounded by the fact the peak summer season for tourists coincides with the period when irrigation needs are greatest in agriculture, WWF claims.

BBC: NEWS | Science/Nature | Tourism damaging Med's wetlands

For example, drip irrigation allowed Mr Thapa to grow cucumbers out of season, when they sold for three times their normal price.

ECONOMIST: Poverty

In Southeast Asia, where they originate, they live in irrigation ditches and rice paddies, thriving there until the dry season, when their pools shrink and they squirm along to the next pocket of water.

CNN: Fish tale

The melt season is often the warmest, driest time of the year, providing large volumes of runoff for irrigation when it is most needed.

UNESCO: 83e