The water savings and methane reductions from improved irrigation management in Bangladesh

Historically, rice is grown in fields that are flooded during most of the monsoon season. However in recent years, mainly due to the availability of tube well irrigation, rice is increasingly being planted in the dry season using shallow or deep tube well water. This trend has led to an increase in groundwater extraction and depletion of water levels in many rice-producing regions.

Researchers at the International Rice Research Institute have developed a technology called Alternate Wetting and Drying (AWD) that works on the principle that the rice plant can tolerate up to 30% less water supply during the growing season relative to conventional methods of irrigation. This technique requires embedding a perforated plastic tube to monitor the water level in the rice field, which is irrigated each time the water level falls more than 15 cm below the soil surface.

The goal of the project is to evaluate the effect of AWD relative to conventional flood irrigation in rice. Our main question is: what is the impact of AWD adoption on farm incomes and water savings? How do these impacts vary across different physical and institutional environments such as shallow and deep water tables, pricing regimes for irrigation water and communal vs private tube well ownership? What is the farmer’s private willingness to pay for AWD technology? Because of the positive effect of AWD in reducing the depletion of groundwater stocks and lowering methane emissions from rice fields, there may be a gap between private and social benefits of the technology, necessitating the use of subsidies for widespread adoption by farmers. A critical aim of the study is to estimate both the private benefits via revealed preference and social benefits, where the latter is achieved by estimating direct effects on methane emissions.