Water from aquatic bodies evaporates into atmosphere due to sun light and condences to clouds. Due to air currents clouds turns into rains and reach water bodies and ground called water cycle. The water falling to earth in the form of rain or snow is Precipitation. Dams are structures used to divide and retain water in a particular area. Some famous dams in India are the Bhakra Nangal Dam, the Sardar Sarovar Dam and the Tehri Dam. Advantages of ground water are –it does not evaporate, recharge wells, protected from contamination of human and animal waste. Disadvantages of dams are deforestation, sedimentation, erosion of river beds, disruption of animal and plant life.
Traditional Water Harvesting Systems are Khadins, Nadis, Bhadaras, Tals, Eris etc Formation of Coal is due to the action of heat and pressure on decaying, buried plants in the swampy areas of earth, and it is a continuous process. Disadvantages of Fossil Fuels are release of carbon dioxide, oxides of nitrogen, oxides of sulphur. Carbon dioxide cause global warming. Our role in energy conservation is to make a habit of recycling and reusing plastic bags, Switch off lights, using CFL bulbs etc.