Adaptation and mitigation strategies to climate change impact for vulnerable Sundarbans

Abstract

Sundarbans in West Bengal of India by virtue of its strategic location in the Eastern coast on the Bay of Bengal falls in the most vulnerable zones of abrupt climate change. Temporal trends of weather parameters of Canning Town (22o18'52'' N Latitude, 88o39'45'' E Longitude, elevation 10 m msl) representing Indian Sundarbans were analysed by non-parametric Mann-Kendall test and Sen’s slope approaches. Analysis of long term rainfall data (1966-2014) indicated that Canning receives a mean annual rainfall of 1818.5 mm (±344.8 mm) with a considerable variation (CV = 18.95%). On an average pre monsoon during the month of March, April and May contribute 13.2% , monsoon rainfall during the month of June, July, August and September contribute 74.3% and post monsoon rain during October to February contribute 12.5% of total annual rainfall. Though most of the weather parameters do not show any trend, bright sunshine hours declined significantly at an annual rate of 0.05 hours yr-1. Reference crop evapo-transpiration (ET0) calculated using FAO Penman-Monteith method revealed that annual ET0 significantly decreased at the rate of 5.60 mm yr-1. Pre and post-monsoon rainfall meet the 49 and 54% of crop evapo-transpiration demand. There was 2.7 times surplus rainfall than crop evapo-transpiration during monsoon months indicating very high scope of water harvesting to tackle water logging during the monsoon season and unavailability of fresh water for irrigation during lean season. Research on Sundarbans regions showed that harvesting rainwater through different land shaping techniques like farm pond, deep furrow and high ridge, shallow furrow and medium ridge and paddy cum –fish cultivation and raising of low land with excavated soil could reduce the impact of saline groundwater table on salinity build up of soil, improved drainage congestion of low-lying land and created irrigation resources for rabi season cultivation. Large scale adaptation of different land shaping models for rain water harvesting in farmers’ field increased the cropping intensity up to 240 % from 119% and net farm income from Rs. 22000 to Rs. 1,23,000 in the region. Water foot print for each of the land shaping techniques was also estimated.