Evaluation of gravity‐led and energy‐fed drainage for sustaining food security in the polders of the coastal zone of Bangladesh

Abstract

Bangladesh is currently self‐sufficient in rice production but faces immense challenges of sustaining that self‐sufficiency because of population growth and climate change. There is little scope to further increase cropping intensity except in the underutilized 1.2 Mha of lands enclosed in the polders of the coastal zone. The main impediment to wide‐scale adoption of more productive cropping systems in the polders is poor drainage that often results in waterlogging. Therefore, a study was conducted in polder 30, in the medium‐salinity region of the south‐west coastal zone, to examine the biophysical and economic feasibility of low‐cost gravity (gravity‐led) drainage. The results show a considerable opportunity to increase rice production in the polders with improved drainage practices. The feasibility of drainage through pumping (energy‐fed) was also assessed, given that there are already situations where gravity‐led drainage is not feasible, and these situations are likely to increase because of climate change‐induced sea level rise and the sinking of polder lands. Energy‐fed drainage was demonstrated to be profitable with a yield gain of at least 1.5 t/ha from just the wet season; further intensification to 50% of polder lands may yield an additional harvest of 3–6 million tons of rice per year. Therefore, investing in improved drainage management in the polders could be a major game changer in sustaining the food security of the nation, especially the climate‐vulnerable polder communities of Bangladesh.

Assessing the Role and Capacity of Water Management Organizations for Ensuring Delta Food Security in Bangladesh

“…Many rural households in the polder zones are highly vulnerable and struggle to meet their food needs in this climate-affected environment (Kabir et al, 2020). Shifting to HYVs of rice, coupled with improved drainage facilitated by strategic sluice gate operations, boosted aman season productivity by a minimum of 1.5 tonnes per hectare compared to traditional farming practices (Mondal et al, 2022). These findings hold profound implications for the food security of farming households residing in the 1.2-million-hectare polder zone.…”

“…The issue of waterlogging poses a significant challenge in the polder zone, causing extensive damage to agriculture (Alam et al, 2017). Mondal et al (2022) demonstrated the potential for reducing waterlogging in polder 30 through gravity drainage, given that the elevation of most agricultural land is higher than river water levels during low tides. Effective water management practices, particularly drainage, are critical for enhancing production and addressing food insecurity.…”

“…Conversely, during low tides, the gates are opened to drain excess water, thereby mitigating flooding caused by high rainfall. The sluice gates are normally closed from the second half of December to the end of June to prevent saline water intrusion into the polder zone (Yadav et al, 2020;Mondal et al 2022).…”

“…The farmers in this region cultivate tall traditional varieties of rice without the use of fertilisers, minimising the need for extensive drainage. However, it becomes evident that efficient fertiliser management, particularly for High-Yielding Varieties (HYV) of rice, requires improved water management practices within the polder zone to attain high yields (Yared et al, 2021;Mondal et al, 2022). Therefore, HYV rice cultivation with improved water management, focusing on drainage for efficient fertiliser management, was evaluated in the aman seasons of 2015 and 2018 (Mondal et al, 2015a(Mondal et al, , 2022, in collaboration with the WMGs and farmers in Fultala and Bayerbhanga villages situated within the catchment of two sluice gates (Katakhali and Khoria).…”

“…Good-quality seeds of BRRI dhan52 (HYV rice) were provided to the farmers to cultivate in aman season. The farmers adopted the recommended crop and water management practices for HYV rice cultivation, including drainage of the ponded water prior to the topdressing of nitrogen fertiliser by systematically opening the sluice gate during low tides and closing it at high tide (Mondal et al, 2015a(Mondal et al, , 2022. The performance of HYV rice with improved water management was compared with the neighbouring farmers' crop and water management practices at both sites.…”