
1) Desert greening
Found on
https://www.crosswordclues.com/clue/check-dam

A check dam is a small dam, which can be either temporary or permanent, built across a minor channel, swale, bioswale, irrigation canal or drainage ditch. Similar to drop structures in purpose, they reduce erosion and gullying in the channel and allow sediments and pollutants to settle. They also lower the speed of water flow during storm events. ...
Found on
http://en.wikipedia.org/wiki/Check_dam

Log, rock, or wood barrier placed across deeply eroded trails or erosion channels to slow the flow of water enough to allow accumulation of fine fill material behind the structure to fill in the trail tread.
Found on
http://www.americantrails.org/

A small dam constructed in a gully or other small water course to decrease the streamflow velocity, minimize channel erosion, promote deposition of sediment and to divert water from a channel.
Found on
http://www.encyclo.co.uk/local/21804

A small dam constructed in a gully or other small water course to decrease the streamflow velocity, minimize channel erosion, promote deposition of sediment, and divert water from a channel.
Found on
https://www.encyclo.co.uk/local/22831
No exact match found.