Monday, March 2, 2009
With this post, I am starting a series to explore the various aspects of sustainable land use. I still have a lot to learn, but a number of basic principles are becoming clear to me. In this series I plan to discuss the basic aspects of these interrelated concepts. I will discuss the complexities (and corrections!) in future posts.
The goal of sustainable land management should be to create a habitable system that
- has very low running costs and labor requirements,
- provides for most of the needs of the people dependent on it,
- generates a substantial profit.
Projected water shortage in the year 2050.
Most urban water harvesting schemes (rooftop collection and storage in dedicated reservoirs), though laudable, are expensive in the short term and neither sufficient nor sustainable in the long run.
To fully utilize the rainfall on a piece of land, it is necessary to
- minimize water runoff
- increase top soil moisture content and productive surface water
- replenish deep underground water reservoirs
The false sense of water security of these techniques spurred wasteful water use and indiscriminate water pollution. Conversely, the impending scarcity has brought us to the point where even the availability of water as a free resource is now under serious debate (even 007 himself got involved! ;).
In light of this evidence, probably the most effective (and cost effective) method is to implement water catchment and groundwater replenishment on the small scale. There are many ancient techniques to learn from and improve upon, but one of the simplest and most cost effective method is creating swales (also known as contour bunding).
Swales are simply long and shallow trenches dug on contour in a sloping landscape, with the dug out material piled on the lower end. This creates a barrier and reservoir for the water flowing down the slope. The water pooled in the trench slowly seeps into the ground, and also provides a stable source of water for plants planted on the mound. Especially in regions where rainfall is highly seasonal and/or irregular, swales are a very powerful way of slowing down the water so that it is available more uniformly throughout the year.
Due to their low cost and effectiveness, swales are an excellent way of beginning a permaculture food forest. These simple water features can be complemented by small interconnected ponds that hold water, percolate it slowly to replenish groundwater, and act as more sites for food production. This method also get rid of the false dichotomy of distinguishing between a 'catchment area' and a 'cultivation area', instead utilizing the available land for maximum productivity.
An excellent example of this approach is Sepp Holzer's* forty hectare mountainside farm in Austria that contains many productive ponds, as well as orchards and vegetable areas:
Do you know anyone that has a small farm or unproductive piece of land? Please tell them about this method of bringing the land back to maximum productivity with minimal investment. With the 3 billion new people joining us on the planet in the next forty years, the only way to for everyone to survive peacefully is to bring all the land back to high productivity without any resource depletion or pollution.
*You can also buy a DVD with three films about the various approaches Sepp Holzers has developed on his farm.