Gravity drainage for cropping intensification in polders of the coastal zone of bangladesh

Bangladesh is currently self-sufficient in rice production; but is facing immense challenges of sustaining it due to the population growth and adverse effects of climate change. There is little scope to further increase cropping intensity except for the underutilized 1.2 M ha lands enclosed in the polders of the coastal zone. The rivers in the coastal zone are tidal with semi-diurnal water level fluctuations of 2 to 3 m and offer tremendous opportunities for agricultural development in the polders, which is not recognized by the professionals and policymakers. The late rice harvest and waterlogged soil prevent timely cultivation of dry season crops. But there are tremendous opportunities to capitalize on polder ecosystem services especially the tidal river dynamics, dense canal networks, water management infrastructure and community water management organizations to reduce waterlogging by gravity drainage during low tides and greatly increase land productivity. Synchronized crop and water management studies were conducted in a medium saline polder from 2015 to 2018 to assess the water inflow and outflow dynamics in relation to land topography and tidal fluctuations in the peripheral rivers and examine possibilities of cropping intensification in the coastal polders. The study demonstrated opportunities for cropping systems intensification and diversification with two to three times higher productivity than with the traditional farmers’ practice through improved drainage capitalizing the water management infrastructure in the polders.