English: River Don aqueduct. The structure ahead is the aqueduct taking the New Junction Canal over the River Don. In times of flood the level of the River can become higher than that of the canal and flow over the top of the aqueduct. In order to prevent the canal then flooding the low lying land each end of the aqueduct is fitted with a guillotine gate which can be lower to form part of the flood defences to keep the river within its banks.