Urban water as an alternative freshwater resource for matching irrigation demand in the Bengal delta

Rapid changes in climate patterns, population growth, urbanization, and rising economic activities have increased the pressure on the delta's freshwater availability. Bangladesh's coastal planes suffer from a shortage of good quality irrigation water, which is crucial for peri-urban agriculture and at the same time, a high volume of untreated wastewater is discharged into the surface water. This calls for a transition towards efficiently managing and (re)using available urban water resources for irrigation, which is addressed in this paper. A quantitative match between the irrigation demand and potential freshwater supply has been assessed considering different urban water generation scenarios. The FAO AquaCrop model has been used to calculate the irrigation water demand for Boro rice during the dry period. Results indicate that 7.4 million m(3) of irrigation water is needed, whereas over 8.2 million m3 of urban water is being generated during the dry season. Simultaneously, mismatches between irrigation demand and alternative water supply mainly occurred in February and March, which could be resolved with water storage capacities. However, to make urban water reuse a reality, the water management policy needs to change to facilitate the construction of required infrastructures for collection, treatment, and storage. The proposed method helps realize the urban water's hidden potential to sustain agricultural activities in the delta areas.

Automated summary

Rapid changes in climate patterns, population growth, urbanization, and rising economic activities have increased the pressure on freshwater availability in the delta. This paper addresses the need for efficiently managing and reusing urban water resources for irrigation in Bangladesh's coastal plains. The study finds that there is a mismatch between irrigation demand and urban water supply, but this can be resolved by increasing water storage capacities. However, changing water management policies and constructing necessary infrastructures are essential for realizing urban water reuse.