Supporting your success 1

NW I Issue 35 I 2013

Raised garden beds in a permaculture garden. Picture by Michelle Frazinelli.

While the causes of climate change are debated globally, it is agreed that weather patterns are shifting and higher temperatures and less rainfall will have significant impact on agricultural production and water supplies.

This will lead to less dam filling and smaller creek and river flows, with ramifications for landholders.

As the weather changes you need to adapt what you do and how you do it according to the resources available.

Here are some tactical (short-term) and strategic (long-term) responses to practical problems.

Shortage of domestic water supplies — tactical responsesShortages of domestic water can occur from time to time.

Apart from bringing in an expensive tanker load of water, there are a number of simple steps that you can take to reduce household water use.

These include:

• Use a basin for the washing up and use the washing-up water in the garden or to flush the toilet.

• Shower with basins and buckets and use the saved water in the garden or toilet.

• Use a shower timer, which reduces showering time.

• Reduce washing machine use and always do a full load instead of several smaller loads.

• Reduce toilet flush volume by placing a plastic bottle filled with water in the cistern.

• Reduce toilet flushing.

• Carry out a survey of tap leaks and fix any leaks immediately.

• Install water saving fittings such as flow restrictors and water efficient shower heads. These are quite low-cost and can be fitted within a few minutes.

• If your water supply depends on harvesting rainwater from roofs, check that all gutters are free of any leaves or material that is going to interfere with the water flowing to the rainwater tank. Check gutters for leaks and

fix or replace leaking gutters. Regularly check that downpipes and tank filters are clean.

• Periodically take water samples from the tanks containing the household water supply and have these tested.

Shortage of domestic water supplies — strategic responsesStrategic response to domestic water supplies:

1. Calculate how much water you use.

2. Make changes to improve water use efficiency in your home.

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Managing domestic and irrigation water supplies on your small property during dry times

noteworthySmall landholder series

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NW I Issue 35 I 2013

Downpipe plug attached to downpipe. Made from a piece of old inner tube stapled to a block of wood with a cup hook and hung next to a downpipe ready for use.

• large, immovable rocks in the soil profile that would make dam sinking difficult and would cause the dam to leak.

New dams and dam improvements should have a high volume to surface area ratio to minimise evaporation.

This is achieved by making dams as deep as the site testing indicates that the dam can go and as steep sided as the machinery can manage.

For the same dam volume and water utilisation, water will last longer in deep, steep-sided dams than in shallow dams with large surface areas.

This is because the deeper water remains cooler and the surface area over which evaporation can occur is smaller.

Where dam sinking depth is limited, it is better to have two small dams with steep sides than one big dam with a much larger surface area.

You can reduce evaporation further by planting suitable trees

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3. Secure your water supply as best you can.

Estimate your domestic water use and identify how much water you might save by changing to a more water-efficient toilet or washing machine. If you still have water shortages it’s time to start looking at the supply side of the equation.

Installation of water tanks to store all the rainfall you can harvest from all roofs is likely to be more cost-effective than enlarging a dam or digging a new one.

Calculate your roof catchment area and the monthly water yield from the roof. If you are building a new house, or adding gutters to an existing building, ensure the gutters slope towards the downpipes. On existing buildings where this is not the case, you could retro-fit by adding additional downpipes where the water pools in the guttering.

A dam solutionWhere you have optimised tank water storage and still suffer water shortages, improving an existing dam or sinking a new dam, may be the next option. This would provide low quality water suitable for toilet flushing, garden, orchard irrigation and firefighting.

Dams can be cleaned out approximately once every five years to remove silt and restore storage capacity. Dam silting can be reduced by growing a grass filter strip above the mouth of the dam.

This needs to be fenced off from grazing. An alternative silt reduction method is to build a bank across the mouth of the dam with wing banks either side facing up-slope to create a short-term storage for run-off.

This causes the water to slow so that it drops a lot of the silt it is carrying. A piped inlet installed through the bank into the dam (usually 2-3 large diameter 15cm poly pipes) allows the stilled and relatively clean water to flow into the dam.

The pipes will need to be anchored into the dam bank as it is constructed. Seepage control baffles should be built around the pipes to stop water flowing through the bank along the outside of the pipes, thereby loosening them.

Ideally the pipes should extend from outside the bank to the bottom of the dam. Water discharging from pipes that do not extend all the way to the bottom of the dam can cause erosion of the inside of the dam wall.

If you plan to enlarge a dam, or sink a new dam, always have the site test drilled first. Good dam sinking contractors will provide this service and this provides critical information for the success of the dam. In particular whether the site contains:

• good water-holding clays and at what depth

• layers of sand seams that would cause leakage if not properly sealed with clay

• salty seepages that would affect the quality of the dam water

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and shrubs on the windward sides of the dam to create windbreaks.

Shortage of water supplies for gardens and small orchards — tactical responsesIf you recognise that you cannot irrigate all your garden and orchard through late spring, summer and autumn, hard choices have to be made over priorities of what gets watered (and how often) and what doesn’t.

Priorities may be:

• maintaining a low fire risk area 20-30m wide all around your house and sheds

• fruit trees and the vegetable garden

• the area of flowerbeds and lawns that you have sufficient water to keep green around the homestead.

Beyond this, short, drought tolerant, non-resinous plants could complete the outer homestead area.

In spring prepare for summer by improving soil and plant health. Have soil samples analysed or carry out your own analysis with kits available at garden shops and many hardware shops.

Apply lime to correct soil acidity and increase the availability of plant nutrients. Incorporate water retaining materials into soils that have naturally low moisture holding capacity and apply soil wetting agents if your soil shows signs of being non-wetting.

You can also add organic matter to the soil in the form of compost by incorporating it into the soil surface or leaving it on the surface as a compost/mulch. Prior to composting or mulching, add nutrients if required, preferably in a

form that will not disrupt beneficial soil micro-organisms.

Apart from making your plants more productive such preparation will make your plants more robust and better able to survive on reduced soil moisture between irrigations.

The most efficient form of water delivery is subsurface irrigation. Proprietary systems of subsurface irrigation are available, but homemade systems for small numbers of fruit trees or shrubs can work well. For example, when planting new trees install a vertical 60cm perforated pipe beside the trees to a depth of around 50cm and irrigate the tree down this pipe.

Another example reuses 2L milk bottles which are perforated and buried up to their necks around fruit trees slightly inside the drip line. Irrigation tubing is installed through a hole in the milk bottle cap. Both these systems supply water direct to the plant roots and limit water evaporation and can facilitate ‘fertigation’ with soluble fertilisers.

Other tactical suggestions for limiting water use in the garden over summer and autumn include:

• use mulch on the soil surface

• reduce irrigation of fruit trees after harvest

• prioritise and limit water supply in the vegetable garden

• use shade over the vegetable garden

• use shade cloth tree guards around new tree plantings

• increase periods between irrigation days for non-productive plants.

Lawn is a special case. Once the soil under lawns has been treated as outlined above to improve soil and plant health, water use on lawns around buildings will be a trade-off between the desire to keep lawns green, water availability and the need to maintain green lawns as a firebreak.

Shortage of water supplies for irrigation — strategic responsesIf after optimising water use, a shortage in water supplies for irrigation still exists it’s time to think strategically about the problem. You can reduce the water needs of garden and orchard by providing windbreaks that will reduce evapotranspiration.

Species chosen for windbreaks should be self-sufficient for water once established. Species should also be chosen carefully to ensure that they are not going to be highly flammable in a bushfire or cause an environmental weed problem.

Subsurface irrigation will be one of the most efficient irrigation systems for vegetable gardens and flower beds and could be used in orchards. Any system that avoids spraying water into the air is likely to be more efficient than sprayers or sprinklers.

Another strategic response to a shortage of irrigation water is to choose plants from arid or semi-arid environments that are adapted to dry summers. Walnuts, pistachios and olives are examples of plants that fall into this category. When seeking drought-hardy plants it is important to consider both the species and

For more informationNoteworthy 20 - Bushfire survival plans for small landholdings

Noteworthy 42 - Calculating livestock water requirements for small landholders

Noteworthy 51 - Establishing effective windbreaks on the Swan Coastal Plain

Noteworthy 56 - Livestock and paddock management for small landholders during dry times

Department of Fire and Emergency Services - dfes.wa.gov.au

Contact detailsSmall Landholder Information Service (SLIS) agric.wa.gov.au/small_landholder +61 (0) 8 9733 7777 or +61 (0) 8 9780 6100

Important disclaimer The Chief Executive Officer of the Department of Agriculture and Food and the State of Western Australia accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it.

© Western Australian Agriculture Authority 2014

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the variety which best suits the soil and environmental conditions that your property offers.

Heightened fire risk — tactical responsesThe Department of Fire and Emergency Services (DFES) has prepared materials on preparation for bushfire seasons, including:

• Bushfire stay or go kit.

• Prepare. Act. Survive.

• Be prepared DVD.

Below are some of their recommendations:

• keep areas around buildings clear of combustible materials

• set up firebreaks or the required fire preparation according to the notice that your local government authority will have sent you — probably with your rates notice

• prepare your own ‘grab and go’ file or box containing important documents and memorabilia

• clean guttering, make downpipe plugs so that gutters can be filled with water if fire threatens (see photo for example of down pipe plug for a rectangular downpipe)

• make a checklist of actions if fire threatens and put it somewhere obvious (e.g. on the fridge).

Heightened fire risk — strategic responses• Draw up a fire plan for your property and place a copy in a waterproof tube at your front gate. Firefighters will refer to this if they need to enter your property. It should tell them where on the property are your high risk areas, sheds where flammable materials are stored (fuel and paint), the location of

buildings, fences, gates and water resources and areas other than buildings which should be saved if possible.

• Remove flammable trees and shrubs from within 30m of buildings.

• Create a tree and shrub-free space around your buildings so that fire brigade vehicles can access all sides of all buildings without the need to reverse.

• Carefully consider fire protection requirements and systems. Money spent on this is property insurance.

• Install a fire pump and water supply independent of mains power and scheme water supply. A 4000L rainwater tank located centrally amongst all buildings and connected to a petrol or diesel powered pump throughout the fire season should be sufficient. Snap on hoses should be close at hand.

• Consider installing a metal roof sprinkler system to be connected to the tank and pump.

• Cover the vents of evaporative air conditioning units with metal flyscreen mesh to prevent embers getting into the house through the air conditioning system.

• Plant fire retarding trees, shrubs and groundcovers as radiant heat shields on the sides of your property from which bushfires are most likely to come.

As the climate continues to vary from year to year, it is a good idea to prepare your house, your lifestyle and your property for dry seasons by taking some of these tactical and strategic steps.