Rehabilitation and modernisation of irrigation schemes

Boosting agricultural productivity to increase food production and raise living standards is a policy in most developing countries as they face increasing populations, rising costs and deteriorating rural infrastructure. Many irrigation and drainage systems built over the last 100 years have suffered from a chronic lack of maintenance, resulting in canal networks that cannot deliver sufficient water. Crop yields and farmer incomes have thus fallen, exacerbating rural poverty. By this stage, deferred maintenance is not effective – comprehensive rehabilitation and modernisation is needed. This entails a hydraulic design review (possibly increasing capacity), improving water level control, water distribution and flow measurement by building new canal structures or modifying existing ones, lining canals as required and installing canal performance monitoring equipment. The author uses his experiences in Pakistan and Vietnam to discuss the different methods of water control used, the rehabilitation of canals and structures, lining criteria, monitoring equipment and cost estimates per hectare for rehabilitating and modernising gravity irrigation systems