Keyline design is a technique for maximizing beneficial use of water resources of a piece of land. The Keyline refers to a specific topographic feature linked to water flow. Beyond that however, Keyline can be seen as a collection of design principles, techniques and systems for development of rural and urban landscapes. Keyline design was developed in Australia by farmer and engineer P. A. Yeomans, and described and explained in his books The Keyline Plan, The Challenge of Landscape, Water For Every Farm and The City Forest.