The Indian Sundarban lies in the tide dominated southern part of deltaic West Bengal and
support of 4.43 million strong population. Freshwater is a scarce resource in the Sundarbans
though it is traversed by numerous creeks and rivulets and receives a huge amount of
precipitation during the monsoon months. Scarcity of fresh water above and below the ground
during the dry season, increasing siltation leading to reducing depth of channels, high salinity
of soil and water along with drainage congestion make it very difficult for the people to secure
their livelihood. The present paper assesses these sectoral water demand and availability in 19
administrative blocks of the Indian Sundarbans. Increasing water demand of the ever increasing
population leads to water deficit in most of the blocks during dry season. Present annual
demands of drinking and domestic water in the Sundarban have been estimated at 8.08 mcm
(million cubic metres) and 105.1 mcm respectively in this study. The water demand for
agriculture has been calculated as 2782.83 mcm by combining the area under different crops
with the lifecycle water requirement of each. The rainfall-runoff modelling has been undertaken
to get an overview of the annual fresh water availability through surface run off. The study
reveals that Sundarbans gets 2000-2500 mcm annual runoff from its upper catchments and the
19 block region generates additional 1800-2000 mcm annual runoff within its territory. Due to
unavailability of proper management options, this huge runoff volume cannot be utilised to
meet the water demand. Block wise water availability from different sources has also been
estimated. The contribution of deep and shallow bore wells is assessed to be around 400 mcm
whereas around 50 mcm water is available from surface water sources like tanks and canals.
This paper also assesses cropping intensity, irrigation intensity and man-cropland ratio in the
Sundarban. The research exposes the growing population pressure on agriculture with an
average man cropland ratio of 14 person/hectare land. Average cropping intensity and
irrigation intensity have been estimated around 130% and 18% respectively. The highest
cropping and irrigation intensity have been observed in the northern blocks where shallow
ground water is available for agriculture. On the contrary, the lowest values have been
observed in the southern blocks, due to existence of saline water in shallow aquifers. Available
water from 70000 freshwater tanks and around 8000 shallow bore wells are not sufficient to
meet the agricultural water demand during the Rabi (winter) and summer seasons.
Unavailability of fresh water restricts food production, which endangers the food security of
87.5% of the people in the Sundarbans. To ensure food security in the present changing climatic
condition, expansion of irrigation network and harnessing of new water sources are essential.
This study emphasises that roof-top rainwater harvesting in this region has potential to supply
additional 45 mcm water which may be used to partly meet the domestic water demand in this
region. Large scale rainwater harvesting, rejuvenation and re-connection of disconnected river
channels, artificial recharge within shallow aquifers to bring down its salinity, de-salination of
shallow groundwater can be some of the major policy options to meet the water demand in the
Sundarbans eco region in future