Harnessing Mathematical Models for Climate-Resilient Irrigation in Bangladesh

Bangladesh, one of the most densely populated countries in the world, has no alternative to feed its 171.2 million population except for increasing food production. The government has also emphasized National Plans to achieve this through optimum utilization of the country's scarce land and water resources. The Kurigram Irrigation Project (South unit) aims to be a surface water-based irrigation project where water will be diverted from the Dharla River by constructing a Barrage. The project goal is to ensure water distribution through a network of irrigation canals to support local farmers and rural communities. This paper highlights the different activities undertaken, methodologies followed, and technologies used to develop the detailed irrigation plan so that the maximum area could be brought under gravity irrigation. An up-to-date topographic map was used to establish the irrigation plan. The irrigation canal layout has been verified in the field to assess its practical suitability, and it has been discussed with local people for their feedback. Full Supply Level (FSL) has been computed so that the maximum area can be brought under gravity irrigation, exceptionally high regions are proposed to be irrigated by LLP, and the least preference has been given to groundwater irrigation. Crop water requirement has been computed using CROPWAT version 5.7 of FAO. The suitability and effectiveness of the proposed canal layout, FSL, various structure locations, and related hydraulic parameters have been tested using a 1-D mathematical model for the irrigation network. The model was developed using the MIKE-11 DHI modelling software. Different option studies have been conducted to determine the optimum parameters by making necessary adjustments in the canal section, structure size, sill, location, and various hydraulic parameters to ensure timely delivery of required water with full supply level at different locations. Finally, the design engineers provided the optimum parameter values so that they could design the proposed irrigation system accordingly and get the maximum benefit from the project.