Explain three traditional methods of rainwater harvesting in India.

 Tanks 

Most houses in Bikaner have an underground tank (Tankas) which were used to store water. They were circular holes  made in the ground, lined with fine polished lime, in which rain water was  collected. It took care of their annual needs. 
 

One tank, one temple and a grazing land for  cattle of a village” was the concept of our ancestors which would support  sustainable growth of villages2. Water tanks served the purposes  like flood control, prevention of soil erosion, reducing wastage of run-off and  recharging groundwater. The management of tanks was given to individuals or to  village communities or to temples. Entire tank system was suitable for direct  irrigation for agriculture and easy for decentralized water management. These  tanks were constructed using stone, cement or mud or a combination of these. Tanks / Eris are one of the oldest in  irrigation engineering designs in our country. 
 

The temples in south India have huge tanks as part of the temple  premises. Some of them have more than one tank. Besides serving the needs of  the temple and use of water by devotees for purifying before darshan these tanks increased ground  water levels. Picture number 9 shows a water tank in the Chidambaram Temple,  Tamil Nadu. To conserve rainwater, the Chola kings built a network of tanks in Tamil  Nadu. Most of these were used for irrigation purposes.

 Kuhl - Himachal Pradesh 
Kuls are water channels found in precipitous mountain areas. These channels  carry water from glaciers to villages in the Spiti valley of Himachal Pradesh.  Where the terrain is muddy, the kul is lined with rocks to keep it from  becoming clogged. In the Jammu region too, similar irrigation systems called kuhls are found. 
In Assam ancient kings  constructed big ponds to preserve rainwater. In some places, the Garh is used to channelize river water  to the agricultural field. A Garh is  like a big nala, where both sides have big and long embankment and the middle  side is left open for water to flow.
Thus it  is evident that many communities in India in the past and present have  effectively employed water harvesting to meet their water needs.Eco sustainable policy of our villages was based  on the concept of land-water-vegetation. Surplus (food, fodder, etc) generated  at the village level supported the towns and cities. Large part of the village  prosperity came from the water harvesting system, which gave them an assured  supply of water for irrigation. 
 

 Talab / Bandhis 
Talabs a re reservoirs. They may be natural, such as the ponds (pokhariyan) at Tikamgarh in the Bundelkhand region. They can be human-made, such the lakes in Udaipur. A reservoir area of less than five bighas is called a talai ; a medium sized lake is called a bandhi or talab ; bigger lakes are called sagar or samand . The pokhariyanserve irrigation and drinking purposes. When the water in these reserviors dries up just a few days after the monsoon, the pond beds are cultivated with rice.