Strategies of water resource utilization and agricultural water management in the coastal saline zone of Bangladesh

Abstract

Access to irrigation water is pivotal for dry season crops in the coastal saline regions of Bangladesh. This research investigates strategic measures aimed at ensuring water availability for polder agricultural purposes in the dry season. This study was performed from 2017 to 2022 to assess the water availability inside polders # 30 and # 31 in Khulna region of the south‐western coastal zone of Bangladesh. Our methodology encompassed diverse approaches: identifying optimal water sources, capturing low‐salinity water for agriculture, implementing crop–soil–water management to enhance cropping intensity, employing irrigation modelling for effective crop planning, utilizing GIS techniques to estimate water storage and conducting impact analysis using satellite images. Irrigation by trapped river water increased the yield of different crops by 13–56% compared with that of farmer‐managed plots. Polders # 30 and # 31 currently have approximately 136 and 190 km of good canals, which store 334 and 502 ha‐m of water, respectively, during the dry period. With the existing stored fresh water, a maximum of 6,680 ha and 10,040 ha of watermelon and a minimum of 334 and 502 ha of boro rice cultivation were possible in polders # 30 and # 31, respectively. However, the excavation of poor and dead canals could increase freshwater storage and crop coverage. The image analysis of polder #31 revealed an increase in crop coverage of 238% from 2017 to 2022, which might be attributed to the introduction of advanced water management technologies and salt‐tolerant cultivars as well as holistic extension approaches by different government organizations (GOs), non‐governmental organizations (NGOs) and farmers. This study will assist in formulating pathways for polder‐scale water management and cropping intensification in coastal saline zones.

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