An open modular ditch liner includes a plurality of open liner sections and at least one channel alignment key. The at least one channel alignment key is sized to receive a thickness of two adjacent open liner sections. An erosion barrier insert may be placed between the ends of two adjacent open liner sections. A radius liner insert may be placed between the ends of two adjacent open liner sections. The width of an open liner section may be expanded with a plurality of side connection keys and a plurality of expandable liner sections. A plurality of pitch expandable liner sections may be inserted between the plurality of open liner sections and expandable liner sections. At least one side of the plurality of open liner sections and expandable liner sections may be mitered.