Just how feasible is large-scale surface water use for irrigation?
Integrating remotely sensed, experimental, and hydrological data to model the outcomes of surface water irrigation in Bangladesh.
The use of surface water irrigation in Bangladesh’s southern delta region is a policy priority for the Government of Bangladesh, which has requested over USD 500 million in donor funds to develop irrigation facilities and infrastructure. At the same time, Bangladesh’s rivers provide a source of income to countless fishermen and provide important ecosystem services. In order to assure national cereal stocks, the ultimate aim of the Government’s proposed interventions is to increase crop productivity and to facilitate increased production of dry season irrigated rice, in addition to other crops. The STARS team in Bangladesh focuses on these issues through experimental and remote sensing work to develop an irrigation scheduling application that makes use of satellite derived imagery. In addition, both CIMMYT and the Institute of Water Modeling (IWM) are collaborating to integrate remotely sensed and agronomic trial information with large-scale hydrological models to assess how water extraction might affect water availability, flow, and the balance of fresh and saline water in Bangladesh’s delta.
This work is crucial for assessing both the potential and impact of surface water irrigation, as no prior environmental impact assessment has been conducted to assess if the quantity of surface water available for irrigation is sufficient to sustain dry season rice production at a large scale, without encouraging increased intrusion of oceanic saline water in the coastal fringe. The STARS team is accomplishing this work by integrating remotely sensed information on cropland extent and availability in Bangladesh’s southern delta, with measurements of irrigation water requirements for a number of crops from three benchmark experimental platforms, in addition to tens of thousands of measurements of river and canal water flows and salinity concentrations. Experts in hydrological modeling, STARS’s partners at IWM are using MIKE-11 software to assess the consequences of irrigation water extraction on overall flow and salinity patterns in Bangladesh’s delta. Further modeling scenarios will assess the effects of large-scale surface water development given anticipated changes in flow and land availability under climate change, through the year 2050, while also assessing if a sufficient level of environmental flows can be maintained for critically important aquatic species upon which fishermen depend for their livelihoods. The results of this research, which are expected in June of 2016, will provide policy guidance within Bangladesh, as well as comprehensive data and a modeling assessment to judge the extent to which surface water irrigation can be safely developed.
Mr. Zahirul Haque Khan, who leads the IWM team, preparing to take measurements of canal water flow in one of the STARS research sites.
Mr. Khan and Mrs. Shume Akter of IWM interview farmers on water use and availability patterns in Barisal, Bangladesh.