Climate Change and Sustainable Irrigation Management in Bangladesh

Abstract

Predictions from different studies reveal that the agricultural sector will face the acute challenges due to climate change. Models have shown that due to such changes, the rainy season will be wetter due to increased rainfall and dry season will be drier due to higher temperatures. This will cause more surface water bodies to dry out making less water available for irrigating crops in dry season. Presently, about 75% of total irrigated area is based on groundwater resources. Due to drying out of surface water bodies, additional pressure will be exerted on groundwater to meet crop water demand. High loss in irrigation systems will also invite more groundwater to pump. This extended withdrawal will threaten sustainable groundwater use. Reports are available on the declining trends of groundwater levels both in urban and some pocket rural areas in Dhaka, Joydebpur, Comilla, and Barind tracts of Bangladesh. Excessive withdrawal of groundwater is one of the principal reasons for water table declination. Though the water loss is much higher in paddy field, it is also quite remarkable in non-rice crop fields. Obviously, the system efficiencies are much lower for the crops. Therefore, it is important to devise ways and means to reduce water losses in conveyance, distribution and application methods. Innovative works are already in progress to address these issues. Alternate drying and wetting for rice irrigation, improved earthen channel, buried pipe water distribution system and hose pipe irrigation for both rice and non-rice crops and low cost simple drip irrigation system for high value horticultural crops (like tomato, watermelon, egg plants etc.) are becoming popular day by day. Drought is another regular phenomenon that has to be addressed properly because a severe drought reduces production of Aman rice grown in monsoon by about 90%. So, in the drought prone area, proper irrigation facility should be developed and at the same time efforts to be employed to develop drought tolerant crop varieties. In the coastal areas, sea level rise will increase salinity intrusion further inland to grasp ­non-saline agricultural lands. Therefore, suitable crop varieties to withstand soil ­salinity need to be developed. At the same time, improved method of cultivation to grow high value crops in the coastal saline areas of Bangladesh will also be developed.