A "Waal" is a man-made channel , which conveys water, usually from a stream and only very rarely from a lake, to the agricultural crops, which are often very far away from it. The term is commonly used, among other things, for the canals artificially constructed in Tyrol/South Tyrol for the irrigation of the fields. Particularly in the South Tyrolean Vinschgau, precipitation is so low due to the geographic location that agriculture is dependent on artificial irrigation.