Nullah

A Nullah is a steep, narrow valley that is characteristic in hilly or mountainous locations where there is little rainfall. A nullah, in a time of heavy rain, will control the waterflow down the course of the valley and release it into a wider opening such as a plain, river or the sea. Depending on the composition of a nullah, location and the ground in which it is formed, torrents of water can quickly carve these into steep-sided valleys.

Nullahs like this were used during the First World War in Gallipoli on the southernmost tip of the peninsula during the Border Regiment's involvement in the Helles Operations of 1915. In many cases these were used as a form of cover to move from one location to another, in much the same way as trenches were used to lessen the number of casualties. Troops could move up and down the nullah to other locations, runners with messages could communicate between Battalion, Brigade and Divisional Headquarters and stretcher bearers could remove the wounded. It was very much dependent on the size and location as to how useful they were as a form of cover for enemy fire.

A naturally occurring nullah is very similar to that of a man-made one, typically in the form of concrete waterways used to control the excessive flow of water, particularly through cities; these act in exactly the same way but with the benefit of delivering more control.