The practice of farming on slopes where plants are placed in furrows around the sides of hills is called contour planting. It slows the runoff of water and reduces erosion. This type of farming has been used in agriculture since about 200BC, but it is now being used in modern urban gardens to reduce rainwater runoff into city sewage systems.
Contour planting is also popular along highways, in public parks, and in private gardens as a method of conserving water and avoiding water pollution. One project led by Dave Dyke, an Ohio State University extension agent, involved a Contour Infiltration Planting for the Delhi Township park system. Perennials, shrubs and trees were planted in raised beds between a soccer field and a playground. The plantings follow the contour of the sloping land, therefore absorbing the runoff from nearby asphalt parking lots during rain storms, decreasing drainage into sewer systems.
Contour planting and rain gardens are being used successfully in modern day horticulture to help our flowering plants as well as the whole environment.
(Reference: Patty Craft reported on a collaborative project completed by master gardeners and Horticulture Magazine. See Horticulture Magazine, Vol. 106, #7 Oct./ Nov. 2009, pp38-41.)