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Not AvailableThe low and flat lands of Sundarbans face two contrasting situations; inundated and submerged with excess runoff in the rainy season and acute scarcity of fresh water in the rabi /summer seasons. Traditionally sole crop paddy is cultivated in this region during the rainy season without any on farm management practice. Meanwhile, some land shaping technologies have been developed at ICAR-CSSRI, RRS, Canning Town such as Farm Pond, Paddy-cum- fish, Ridge and furrow etc. These technologies not only helping to store flood/runoff water and reducing drainage congestion during the rainy season, supplemental life saving irrigation of crops during dry period has become possible. The upland formed by putting the dugout soil dries earlier than the medium and lowlands and provides scope for cultivation early in the post monsoon period. A solar drip irrigation system installed at the experimental farm of CSSRI, RRS, Canning station resulted in 60 percent saving of labour, 30-40 percent saving of water with 20-30% increase in yield than the traditional cultivation of same vegetable crops in the rabi season. Tomato was the best crop during rabi season in terms of return. However, Okra was more tolerant to flash flood and salinity than red beet, cow pea and basella as a summer crop. Thus, suitable crops along with modern irrigation techniques can provide scope for crop diversification and intensification in the backward coastal region.ICA

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Not AvailableThe scarcity of good quality water in coastal saline belt in West Bengal is one of the major limitation for growing crops in the rabi/summer season. Despite of excavating many farm ponds covering a considerable area, the stored water in them during the rainy season vanishes within a short duration after the monsoon. This stored surface runoff water is also quantitatively insufficient to meet the irrigation demand for large scale rabi/summer crops. Therefore, the farmers have started exploiting the ground water through shallow tubewells since a few years back. Because of the salinity constraint, somewhere they are suitable for irrigation and somewhere not. The water quality varies from aquifer to aquifer. Five shallow tubewells in Chandkhali village were considered for the study. The shallow tubewell of least depth (240 ft) yielded more saline water than the others having depth 360 to 380 ft. The design details, aquifer positions, their utilization for rabi/summer crop, crop grown and the implications in salinity etc. were studied. The water quality (EC) in the tubewells of more than 350 ft were found suitable for irrigation in the rabi/summer period though the discharge rate generally reduces towards the late summer. As the ground water potential in this region is very high, if the water quality is suitable, then the ground water can be used for increasing the cropping intensity. However, over-exploitation should be avoided to prevent deepening of the water table and saline water intrusion.Not Availabl

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Not AvailableAgriculture in the Sundarbans of India is mainly mono-cropped with kharif rice (aman) grown in the monsoon season. Scarcity of fresh surface water for irrigaon during the post-monsoon period is the main constraint on growing boro (post monsoon/dry season) rice and other crops. Therefore, there is increasing exploitaon of groundwater through shallow tube wells (STWs). At present, STWs are used to irrigate about 32% of the total irrigated area of approximately 55,300 ha in the Sundarbans. However, there is concern about the sustainability of current rates of groundwater use and its connued expansion. Therefore a series of surveys was conducted on the status of STWs in South 24 Parganas and North 24 Parganas districts from 2000 to 2014. The depth of STWs varied from 67 to 128 m below ground level (bgl). A study throughout 2003 showed that the piezometric pressure level was highest and salinity was least aer the monsoon (November-December) and that piezometric level was least and salinity highest before the onset of the monsoon (May-June). The piezometric level and water quality recovered during the 2003 monsoon. Detailed study of STWs used for irrigang boro rice in 2003, 2009 and 2014 showed that the piezometric level decreased significantly from an average of 2.1 m bgl in January to 3.9 m bgl in May while the discharge rate decreased significantly from 10.8 to 7.2 ls-1. Over the same period, groundwater salinity increased significantly from an average of 2.0 to 3.7 dS m-1. Salinity (ECe) of the topsoil (0-15cm) in boro rice fields irrigated from STWs increased significantly from an average of 3.0 dS m-1 at sowing to 5.8 dS m-1 at harvest. The grain yield of boro rice increased significantly with increasing installaon depth of STWs. STW depth accounted for 70% variaon in grain yield and this was at least partly due to a significant decrease in water salinity with increasing STW depth. While the piezometric level and water quality recovered during the 2003 monsoon, whether this would be the case in more intensively irrigated areas is not known. The sustainable level of groundwater use needs to be determined across the region. Measures for more judicious use of groundwater are also needed to increase producvity of this precious resource.Not Availabl