Mitigation of Water Crisis and Growing Crops in Lean Period by Rainwater Harvesting through Concreted Rooftops and Household Ponds in Sagar Island

Anadi Gayen^1*, A. Zaman²

¹Central Ground Water Board, Eastern Region, Kolkata, India.

²Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India.

DOI : http://dx.doi.org/10.12944/CARJ.1.2.03

Abstract:

Groundwater occurring in the shallow aquifers is highly saline and is not suitable for drinking. Fresh potable ground water is occurring at great depth (245–325 m bgl). Occurrence of fresh ground water at deeper aquifers restricts large scale groundwater development, because it is beyond the economic capacity of common people. Source of drinking water is mainly Government owned hand pump fitted tube wells. Approximately per 70 households only one such tube well has been allocated. Many of these tube wells are yielding very less quantity of water during peak summer. Hence, the island is suffering from potable water scarcity especially during summer for around 4-5 months. Water supply is available in very few villages. Almost all the households are having one or two ponds. Most of the ponds are dried up during summer. Therefore, people in the island are facing water shortage round the year. The island receives very good precipitation (1900 mm) during monsoon. Major quantum of rainfall is lost as surface run-off to the sea or rivers. If this rain water run-off can be arrested and stored, island may be developed in many ways. There is a vast scope of Rain Water Harvesting (RWH) in Sagar Island. Water conservation can help to minimize the huge monsoon run-off. Roof top rain water harvesting can solve the drinking and domestic needs of the people of Sagar Island. In this context, harvesting and conservation of roof top rainwater during monsoon in storage tanks and ponds were explored, so that the same can be utilized in the lean periods. Present study has aimed to understand total amount of water may likely to be available from the concrete roofs of different existing buildings like public offices, schools, guest houses and individual houses as well as household ponds. At present, total water requirement of Sagar island in peak summer (4-5 months) for drinking and domestic uses is around 1589947.50 cu. m. Total amount of rain water be conserved through small household ponds (12418) and concrete roof tops (3194) is 3692853 cu. m. of which ponds contribute 3588976 cu. m. water and concrete roof tops used to contribute 10,38,77 cu. m. water. Thus, this conserved rain water could able to benefit in catering 492380 people (i.e., more than double of present population) of Sagar Island for five months in peak summer for drinking and domestic uses.

Keywords:

Concrete Roof; Household Ponds; Rainwater; Rooftop Harvesting

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