By definition a ‘Watershed’ is a drainage area (basic hydrogeological unit) on earth’s surface from which runoff resulting from precipitation flows past a single point into a large stream, a river, a lake or the ocean. The runoff generated can be collected in a pond or a reservoir by means of mechanical/structural and vegetative measures. This stored water is then supplied to fields under gravity flow for irrigation purposes. A watershed maybe of any size but it must be manageable hydrologically. It is very much ‘natural’ and it allows planners to focus on all the effects of downhill runoff in a given area and to plan accordingly to control or contain it. 

Watershed based management has been accepted as the most rational approach today. Besides water harvesting with special reference to rainfed agricultural lands, it includes a wide range of activities including soil and water conservation, development of degraded and waste lands, afforestation and employment generation amongst rural people. In the long run, it preserves the ecosystem, restores the environmental degradation and stablises and sustains the overall productivity of an area. The key concepts which are included in watershed management are: 

• Landuse planning and utilization based on potential. 
• Rain water harvesting 
• Maintaining good vegetative cover over the ground of minimize erosion of soil and water and maximize water retention in the soil. 
• Draining out excess water to pond/reservoir for future use. 
• Developing relevant soil and water conservation structures to control erosion. 
• Maximizing productivity per unit area, per unit time and per unit of water and increasing cropping intensity. 
• Utilization of marginal lands to its maximum potential use. 
• Maximizing and stabilizing income of the people of the areas through integrated crop-livestock tree labour complex. 
• Developing rural energy management systems, infrastructural facility and improving health, education and other socio-economic conditions of local residents.
• Finally, restoration of the ecosystem towards achieving sustainability
  
  Source: E.News