Global warming and drainage development : Perspective and challenges

Irrigated agriculture is expected to play a major role in reaching the broader development objectives of achieving food security and improvements in the quality of life, while conserving the environment, in both the developed and developing countries. Especially as we are faced with the prospect of global population growth from almost 6 billion today to at least 8 billion by 2025. In this context, the constraints posed by land and water scarcity and the associated need to increase the carrying capacity of the land in a sustainable manner will require significant enhancements in efficiency and flexibility of irrigation and drainage systems in the next few decades. In most of the world's irrigated and rainfed lands, drainage facilities were developed on a step-by-step basis over the centuries. In many facilities structures have aged or are deteriorating and, consequently, they need to be renewed or even replaced and thus, redesigned and rebuilt. In the past, drainage systems were designed for a long life, on the assumption that climatic conditions would not change in the future. This will not be so in the years to come, due to global warming and the greenhouse effect. Therefore, planners and designers need to systematically re-examine planning principles, design criteria, operating rules and management policies for new infrastructures. In relation to these issues and based on available information, the report gives an overview of current and future (time horizon 2025) drainage developments around the world. Moreover, the paper analyses the results of four of the most advanced global circulation models for assessing the hydrological impact of global warming, due to the greenhouse effect, on the drainage planning and design process. Finally, a five-step planning and design procedure is proposed, able to integrate, within the development process, the hydrological consequences of climate change. Copyright