Chapter 7 - Optimising irrigation management at the plot scale to participate at the regional scale water resource management

Abstract

According to the FAO, a great challenge for the coming decades will be the task of increasing food production to ensure food security for the steadily growing world population. Most of that increase will have to come from intensified agriculture, supported by irrigation. Where irrigated agriculture is developed, water used for irrigation can represent more than 90% of water consumption. In an increasing number of countries, existing resources are fully exploited. Drinking-water supplies and the maintenance of a continuous, minimum water flow in rivers are often given priority over irrigation. Planning and management of water resources have become a very important issue everywhere in the world. In particular, accurate estimation of water demand by agriculture is a key need for water management. Water management includes planning (with decisions on a multiyear time scale, such as building dams), strategic management (seasonal decisions with possible adjustment during the season, such as determining the total water volume used for irrigation), and tactical management (daily decisions, such as releasing water from particular dams). Developing tools by integrating knowledge in models may be of some help for planners. However, modeling water management is complex because it concerns different scales (scale of decision, scale of action, scale of planning, scale of management) and different actors (water users, including farmers, factory managers, and general public, policy makers, and water manager). Crop models that simulate the dynamic of plant growth and water demand of one or several crops can provide quantitative contributions to the environmental impact assessment and be very useful for water management