Rainfall is a primary source of water and roof top harvesting of rainwater has tremendous scope in improving groundwater availability and quality,observed PAU expert Dr Rajan Aggarwal of the Department of Soil and Water Engineering. Providing an in-depth knowledge to the farming community,the scientist disclosed,More than 96 per cent of cultivated area in Punjab is under irrigation and out of this,about 70 per cent is irrigated by groundwater. The number of tubewells has increased from 1.92 lakh to 12.76 lakh in the period between 1970 to 2008-09. The excessive exploitation of groundwater has created a declining water table situation in Punjab. He stressed that there is a dire need to conserve water using all possible techniques to enhance groundwater availability.
The expert,educating the farmers,said that the rainwater collected from the rooftop,is free from chemical and biological contamination. Moreover,with 1 cm of rainfall,1,000 litre of water can be harvested through 100 meter square of roof area.
Dr Aggarwal emphasized that there is a need to adopt this technique at mass level to get significant results.
In Punjab,26 lakh hectares of land is under paddy cultivation. The paddy field can also be used for conserving rainwater by increasing the dike height of the paddy field, revealed the PAU scientist.
It has been recommended that for maximum rainfall conservation,the optimum effective dike height in paddy fields should be 15 cm,17.5 cm and 22.5 cm for light,medium and heavy soils,respectively.
Apart from reducing flood hazard,these techniques will also improve groundwater quality substantially.
There are about 18,000 village ponds in Punjab,these ponds can be deepened and renovated for direct irrigation and recharge purpose, added Dr Aggarwal,while warning farmers to keep a check on the inflow of pollutants into these ponds.