The impact of the proposed rubber dam facilitated surface water irrigation on adjacent groundwater at Chapai Nawabganj district, Bangladesh

Abstract

Abstract The dry season irrigation primarily depends on groundwater in Bangladesh. The over-abstraction, along with decreasing recharge, is depleting the groundwater resource across the country. Consequently, the government of Bangladesh is planning to switch from groundwater to surface water irrigation. In line with this, Bangladesh Water Development Board has proposed to construct a rubber dam on the Mohananda river at the Chapai Nawabganj district. This work investigated the impact of the proposed reservoir facilitated surface water irrigation on the adjacent groundwater in the study area. A coupled river–groundwater modeling technique was used to predict the long-term groundwater condition. Results showed that the groundwater lowering rate reduced to 50 mm/year inside the irrigation zone compared to 87 mm/year outside the zone. Also, the augmented surface water irrigation raised the groundwater over an area of 141 km2 and 242 km2 in 2029 relative to the base condition of 2013 and existing irrigation practice if continued, respectively. Besides, the raised groundwater resulted in a higher discharge from the aquifer to the river. The study concludes that increased surface water irrigation successfully lowered the groundwater declination rate, especially in the surface water irrigation zone.

Keywords

• Groundwater model
• Rainfall–runoff model
• River model
• Coupled river–groundwater modeling
• Surface water irrigation