Imagine that you dwelt in a land prone to flooding, or that there were land pressures that meant that you had no access to agricultural land, but you needed it. The solution is to grow on floating rafts made of vegetation. This technology is very ancient. At In Le Lake in Myanmar the locals dwell on the shore, but makes rafts out of plentiful weeds to which they sail out to cultivate their crops. As the lake rises when it rains, the gardens rise with the water, and so never flood. The simple houses can be flooded, but the food supply remains safe. The advantage is that as the lake is an enclosed space the rafts never drift far, and they can be tethered to long ropes and given markers so that families know whose raft is whose. This technique of tethering is used in Mexico.
Bangla Desh, a flood-prone land, is taking an interest. Many peasants have their land flooded and their crop destroyed by massive floods surging down from the deforested Himalayas, but now peasants in some areas are being encouraged to design floating, flood proof gardens. These are particularly suitable for areas such as lake sides where currents are not likely to sweep away the garden. Bangla Deshis are encouraged to keep fish in wire cages, so that if their fish farms flood their stock does not wash away.
The charity,Practical Action, advocates intermediate technology, which is half way between low technology, which impoverished communities possess and which keeps the poor impoverished, and high technology, which cannot easily be installed or maintained in many communities. Intermediate technology uses local knowledge, skills, and resources to achieve its goals, and it empowers communities and individuals, particularly marginal or oppressed groups, rather than large companies. The floating gardens of Bangla Desh have been advocated by Practical Action and have particularly empowered women, giving them the ability to own some productive land.
In fact, floating gardens have a long history. They are natural occurrences which arise when vegetation mats at lake sides break away from the shore. In Britain they probably occurred when we had more lakes, and when lake shores were not as tidy as they are now. In age when many Britons dwelt in Crannogs, villages built on piles in the lake, floating islands were probably common, though there is no evidence of vegetable growing on them, but such evidence would soon have disappeared,so absence of evidence is not evidence of absence. In Lake Titicaca Amerindians have long dwelt on floating islands, which were places where they felt safe from raiders.