Yesterday I mentioned that we have recently had some earth works done. We have a small mixed farm on the outskirts of a major rural city. This city once was a large producer of food for the local area and Sydney. There were dairies, beef cattle and market gardens. Nearly all that is gone now, even though the land is prime food growing land. The reason for it's productivity is that this food growing land is traditionally flood plain.
Now, turf and hay growing has largely replaced food production in our area (apart from that land which now has housing on it ). This non food productivity still requires the same, if not more, irrigation. The water is drawn from the river that the city was built around. A life sustaining resource. The river, in our area, is a mess. It is silted up in many areas and contains contaminants from both the coal mining further up river, and pesticides and artificial fertilisers from the lucerne and turf farms. I have a friend living near the river with an irrigation licence for their olive and beef farm. They had the water tested and it's far too toxic to use, but that doesn't stop others from using it.
The river is being used and abused. It is used to grow inappropriate water guzzling crops without any regard for chemical runoff and industry that allows runoff flow into the river.
We don't have access to the river for our farm, and wouldn't use it anyway due to it's toxicity. We also question the overuse of this wonderful resource and what affect it's use has on the river itself. We live on very marginal land. It's appeal comes from it's peri urban position. We grow food for people and our customers live close by. We have set ourselves up as a model of sustainability. We aspire to show people what can be done with a less than perfect piece of land in a way that the system sustains itself. This includes taking care of our own waste (eg Composting toilets),catching and storing energy (eg Solar power), limiting inputs and using resources to their full potential.
One area in which we have limited our inputs is our use of water. Growing vegetables requires a lot of water and as we have no source other than rain water we have had to come up with ways of storing it. When we first moved here the only water catchment was 2 small dams at the bottom of the property. They don't hold a lot of water but are quickly filled when it rains. This a great resource in times of drought but as the main irrigation source not really viable. For the gardens we needed something close and easily filled. We brought in a excavator and for 4 days it moved earth around and at the end of the 4 days we had 2 irrigation ponds, new roads , and a swale (a water absorption ditch on contour)
Here is our garden in flood.
You can see one of the ponds at the back with a v drain running along the side of the garden which diverts the runoff into the pond. Can you see the large amount of water in the background. That is in the vacant property behind us.
This is the water coming from next door including the water from the area pointed out in the photo above, behind our place. In this photo it is washing away our driveway. This can happen even after just a few days of heavy rain. Seems a waste, especially when we need lots of water for irrigation and we live in such a dry area. (hard to believe when you see these photos) It has always been a dream to catch and store this water, so a plan was hatched, and the excavator called.
The idea was to build a dam that would take all of that excess water that was causing damage to our drive and public road and storing it for our own use.
While we had the excavator here we had posts driven into the ground to be used as a jetty so that we can also use the dam as a swimming hole.
Here you can see the excavator hammering the posts in. Wow what a sight that was!
Excess water from the dam flows into a swale below the dam. Mark and I used the laser level to mark it out and the the machine dug it out. The swale, a ditch on contour, is used to catch overland flow, to hold it for a few hours or days. The water eventually seeps into the ground essentially recharging groundwater. Trees are essential for swale efficiency, so we have some work to do in planting, but will wait until we have had some good soaking rain.
The water from this dam, apart from swimming in , will be used via gravity to water a wood lot, grapes and olives.It is hoped that, along with the water tanks, irrigation ponds, and older dams, that this dam will drought proof the farm.
Excess soil from the excavations was used to add to, and build earth berms. These berms will be planted out with trees as a windbreak. We will use native trees and grasses for this planting. On the banks of the swales some natives as well as leguminous trees and fruiting trees will be planted. All will be heavily mulched to help conserve water and reduce erosion.
All these water harvesting concepts are equally applicable to urban areas as well as small acreages and large farms. I have seen swales used around fruit trees and used to catch and hold water that would otherwise flow out into the storm water drains. We just need to use different scales.