WATER HARVESTING

This subject has been mentioned in a previous issue, but we believe it is worth talking about again, and again, until it becomes normal practice. We want to share this increased knowledge with you, our reader, in the hope that we, as a community, can begin taking steps towards solving one of the biggest problems that affects all of us to some degree.

I strongly believe that water harvesting, in one way or another, earns itself a place to become popular as a water solution just as solar is becoming for electricity. What is water harvesting?

It is the channeling and storage of available water for continued use.

Why should we do it?

Cities are undoubtedly being confronted with a major water crisis, with some of the cities’ most prevalent boreholes being reduced to seasonal functioning at best. Without the aid of a reliable, regular and healthy water supply from city council, every household (that can afford it) has been forced to invest, at great cost, in a borehole. However, as the water table often stands, this is no longer a guaranteed solution! People are spending thousands of dollars in the hope of attaining what

some deem our most basic “human right”, only to come up empty-handed. Water delivery companies have become a Godsend; providing many of us with water that we would otherwise have no access to. But what would happen if even their stocks ran dry?

Nature provides us with the solution to our problem, if we only meet her half way.

What is the water table, and what happens to the rain?

The water table is the upper surface of ground water. Ground water is the area underground that is totally saturated with water. Rain falls, and if the ground is conducive to infiltration, the soil stores it for use by the plants, known as soil water. If the conditions are right and there is enough water, then it filters down through rocks and sand, and is known as vadose water. When there is enough water to fill air pockets or the space between sediments, then the ground becomes saturated and that is the level at which we draw water.

The water table rises and falls with the seasons, but it is also dependent on a variety of other factors.

The first is of course the level of rain in our rainy seasons, which up until now have been relatively poor in recent years. The surface of the ground also plays a part. Commonplace and therefore often disregarded, uncovered soil dries out easily, allowing moisture to evaporate before it reaches further down. The drier the soil from continued sun exposure and little moisture, the more difficult it is for the water to filter through and finally make it down to the water table. Where luscious gardens stand in the rainy season, without excess water to tend to them in dry months, many homes become almost desert-like, which only perpetuates the cycle.

With continued housing developments, the more concrete we put down, the less surface area we leave for the rain to infiltrate into the ground (unless of course we compensate by harvesting off our roofs). The drainage system is designed to take away the water, and off it goes, unable to sink down into our water table, or be of any use. Altering the natural flow of water also increases the likelihood of soil erosion and many resulting problems due to overfilling rivers with all the water that was meant for the water table. Housing developments on wetlands further worsen the cause, for we are interfering with nature in a way that is precisely contrary to the purpose of a wetland. Environmental hazards, for example, uncaring factories or broken or full septic tanks, cause toxic load on the water table, and in some cases render parts of it unusable. Add in increased boreholes, and the already dwindling water table is being reduced by so much more.

However, as is the crux of this whole article, we can do our bit to turn this plight around. Let’s simply accept nature’s gifts and gift her in return! How do we harvest water?

There are a variety of ways.

1.Collection from gutters and roofs This is the most commonly understood and practiced variation, whereby rainfall is harvested from the roof via gutters and piped into storage tanks for use.

Measure/pace your house and the other buildings on your property, and calculate the surface area of your roofs. 1mm of rain on 1m2 of roof = 1L of water. A conservative rainy season would perhaps give us 600mm of rain, so, even during a relatively poor rainy season, your roofing structure would _________________ (Surface area) x 600mm = _____________ L

N.B. Even your driveway or pavements could be possible capture surfaces!

Call AIDG if you’re interested in options 1, 2, or 3 of this list.

2.Swales

A swale is a constructed barrier on contour designed to capture the rain run-off and cause it to drain into the soil, before it reaches the water way. If your property is big enough, it could prove to be a viable option. It’s a great way to start increasing the coffers of underground water, and head

towards sustaining your borehole or well. 1mm on 1hectare = 10,000l

3.Boulder Checks

Usually done on farmland or bigger tracts, these are low rock walls built to specification in gulleys and water ways, designed to slow the water down and sink into the soil, similar to the effect of swales. Search YouTube for fascinating stories about what boulder checks can do. A wicking bed is any type of plant container which has its own supply of water stored below. This method of irrigation is reported to have up to 80% water saving, because the plants take up only what they need, and less water is lost to evaporation. More to come on wicking beds in future issues.

6.Wells

4.Grey Water Systems

Water from the house, other than that from the toilet, is considered grey water. With little effort or expense, this water can be filtered through organic means and repurposed for irrigation, thereby using the same water twice. An ancient and affordable solution to tap into the water table, wells are usually 10m - 20m deep and dug 1m in diameter, and then lined with brick. For water divining and construction of wells, call Elton: 0778932244. Surprisingly in some instances, wells can provide water where boreholes don’t.