Abstract - In the Abundance of Water, The Food is Thirsty
The scramble for Africa was motivated in part by the desire of some peoples to possess the abundant natural resources she is blessed with. This same desire to possess resources that other nations have in relative abundance has led to an untold number of wars. Against this background, some have predicted that the wars of this century will be fought over water.
Water has been described as the most strategic resource on the globe. It is essential for every society and individual, is critical for economic development, for social welfare, and is home to a great many forms of life upon which the well-being of all human beings depend. Though the globe abounds in water resources, the amount of fresh water available to man is finite and rapidly diminishing both in quality and quantity.
An amount of 3240 Km3 of fresh water is withdrawn and used annually. Of this total, 69% is used for agriculture, 23% for industry and 8% for domestic purposes. These values vary from continent to continent, and in Africa and Asia, about 86% of fresh water is used for agriculture, mainly irrigation.
Irrigation and drainage have over the centuries contributed significantly to the increase in food production. Today, only a meagre one-sixth of cropped land that is irrigated produces one-third of the world’s harvest of food crops.
These contributions are however, not without costs; of the amount of water that is allocated for irrigation, system water losses make up 15%, farm distribution losses 15%, field application losses, 25% and only 45% is actually utilized by the crops.
With an increasing world population, increased agricultural production is required to provide enough food and fibre. This cannot be achieved without greater withdrawals of water for irrigation but this would worsen the already scarce freshwater situation. A way out of this situation is the development and adoption of irrigation and sometimes drainage methods and techniques that are efficient in terms of use of water as well as environmentally friendly. These methods and techniques can be classified as ‘water saving irrigation” methods and techniques
In this lecture, I present the global water picture, then discuss water in agriculture. I look briefly at the water situation in Ghana, then present some of my research in water saving irrigation. Within that, I consider the impact of climate change on water use of some crops in some districts within Ghana, I then consider Deficit Irrigation, an irrigation water saving technique, and end by considering Water Table Management, which combines irrigation and drainage, and leads to water saving as well as makes drainage environmentally friendly.