Give A Dam by Prue Batchelor

GIVE A DAM CAN THE ORDINARY FARM DAM BE IMPROVED BY DESIGN? AN EXPLORATION OF THE GREAT SOUTHERN AGRICULTURAL LANDSCAPE AND ITS FRESH WATER MANAGEMENT TAMBELLUP, WESTERN AUSTRALIA

DESIGN THESIS BY PRUE BATCHELOR 583 435

MASTER OF LANDSCAPE ARCHITECTURE UNIVERSITY OF MELBOURNE 2020

SUPERVISOR: A/PROF MARGARET GROSE

My deepest gratitude and thanks goes to my family who instilled a love and appreciation of the land we walk on, work with and admire. Itâ&#x20AC;&#x2122;s been the safety I return to and the catalyst of my interests. My Dad, the constructive critic, stubborn farmer and land steward. My Mum, green thumb, nature nurturer, adaptive and resilient like the land she works with. Thankyou so much to Leon for being a calming sounding board, advocate and landscape enthusiast. Many thanks also extends to Margaret Grose, who supervised my work and has inspired me throughout this course to thoroughly respond to landscape issues through reading, immersion, conversation and science under the umbrella of landcape architecture. Thankyou to all who have contributed to my research and collaborated through interviews, conversations and shared experiences. Farming and its longevity relies on this kind of participatory information, exploration and adaptation.

“Farmers have on-the-ground knowledge, but “what they are missing is design.” Farming done well, much like landscape architecture, is a genius melding of art, science, and place. The opportunities for designers are abundant.” - Kelly Mulville,

Paicines Ranch

“TASSAJARA” and “FINISTERRE” - Our Farm

“I began life as a farmer, and although for forty years I have had no time to give to agricultural affairs, I still feel myself to belong to the farming community, and that all else that I am has grown from the agricultural trunk.” - Frederick Law Olmsted,

Pioneer of Landscape Architecture profession

CONTENTS THE AGRICULTURAL LANDSCAPE AND ITS FRESH WATER MANAGEMENT

A REGIONAL CONTEXT

ESTABLISHMENT OF AGRICULTURAL PRACTICES A SALTY COMPLEX A HYDROLOGICAL CONUNDRUM AGRICULTURAL ADAPTATION TO FRESH WATER SCARCITY

A CRITICAL LANDSCAPE

THE FARM AS IT IS - ENVIRONMENTAL CONDITIONS MIXED PRODUCTION SYSTEMS WATER SYSTEMS ON SITE

COLLABORATIVE INPUT

INTERVIEWS WITH LOCAL REPRESENATIVES AND FARMING STAKEHOLDERS AGRICULTURAL PRECEDENTS FOR IMPROVED FRESH WATER EFFICIENCY

DESIGN STRATEGIES

ENVIRONMENT VS ECONOMICS; UNCOVERING RESISTANCE DESIGN CONSIDERATIONS AND EXPLORATIONS CRITICAL REFELCTION: VEGETATION AND MATERIALS TIMELINE OF IMPLEMENTATION

HOUSE DAM: A FAST SOLUTION TO FRESH WATER COLLECTION AND STORAGE

DESIGN STRATEGY: EVAPORATION MITIGATION AND DAM WATER COLLECTION DESIGN OUTCOME

WHITE DAM: NOT A DAM AT ALL - DESALINATION

DESIGN STRATEGY: WORKING WITH SALT DESIGN OUTCOME

WEST DAM: A LONG TERM COMMITMENT TO IMPROVED FARM SYSTEMS

DESIGN STRATEGY: ONE LANDSCAPE AND THE PRODUCTIVE VALUE OF CHANGE DESIGN OUTCOME

CONCLUSION

REFERENCES

THE AGRICULTURAL LANDSCAPE AND ITS FRESH WATER MANAGEMENT

I grew up in an old farming family in the Great Southern of Western Australia, a 150 year old agricultural community and one of the most productive dryland farming regions in Australia. This landscape is curated by saline systems of lakes and rivers, exacerbated by intense land clearing in Australiaâ&#x20AC;&#x2122;s global biodiversity hotspot. Farm damsâ&#x20AC;&#x201D;clay-based, rectangular or square, stock-driven and compacted â&#x20AC;&#x201D; are placed on degraded soils and disrupted groundwater tables. On-going water deficiencies in the region, susceptibility to drought, and dryland salinity mean that improved freshwater capture is vital for the sheep that maintain my community. As with the rest of Australia, dams here have been based on the same design for all those 150 years. The intention of this project is to achieve design based outcomes that have the potential to stabilise water availability in the short term, whilst improving biodiversity, and the natural function of the landscape. The stabilisation of fresh water resources is the foundation for continued agricultural practices in this region. This thesis will contribute to future agricultural trends for this area and highlight the the role of salinity and the importances of maximising landscape opportunities. It aims to positively position the farm for short and long term economic viability and rework existing environmental relationships to ensure fresh water solutions on farms. The proposal suggests improving fresh water efficiencies by minimising evaporation, mitigating salinity by lowering the groundwater table using vegetation, utilising saline groundwater and maintaining and enhancing biodiversity by creating habitat. These considerations must act symbiotically in order to be successful and achieve the economic bottom line for farmers to realise the productive value of change.

Salt gully and scold along low lying land on the farm. Source: Prue Batchelor, 2020

18 and 19 December, 1835 - Moving North t (modern day) Tambellup-Broomehill-Katan

NATIVE GRAXING ANIMALS ON RUSH PASTURES

JAM, WATTLE, BLUE GUM (INDICATION OF GOOD SOILS)

A REGIONAL CONTEXT ESTABLISHMENT OF AGRICULTURAL PRACTICES

through nning N

Early explorations of this land by John Septimus Roe found minimal fresh water sources, continuous salt water systems in the form of pools and perrennial streams, which is known as a chain of saltwater ponds. Simultaneously, areas close by were rich in grasses and tree species, which indicated soil and loam profiles of exceptional quality. A unique situation, whereby dryland farming is not and can not be facilitated by freshwater systems as salt has always been present. In an area deemed excellently suitable for sheep grazing, the need for fresh water to sustain them was vital, and so, the clay-based, square dam was devised to capture ground run-off (Hercock, 2014).

“Excellent pasture land for cattle or sheep” - a visual identification of the landscape about the prospects of agriculture in this region by John Septimus Roe, Surveyor 1835

Scamper Creek (salt) (Broomehill/Katanning)

“Most abundant supply of surrounding grass and wells of good drinking water.../...excellent pasture land either for cattle or sheep” Rich, loam soils

TASSAJARA/FINISTERRE

Light loam on ridges.../...jam trees, red gum and white gum

Pools of fresh water (Summer) Kent tRiver (Cranbrook)

A REGIONAL CONTEXT A SALTY COMPLEX

Industrial agriculture has been the driver of these communities but changing conditions, both anthropogenic and natural has led to severe land degradation. The equilibrium that existed in the landscape was achieved through deep rooted native vegetation keeping the groundwater table below embedded salts. Accelerated land clearing and successive shallow-rooted cropping has led to dryland salinity; an exacerbated process. My grandpa, our neighbours and our friends were all culprits of these actions, but they were encouraged by government and advisors. These practices weren’t stopped until new knowledge, science and resources became available. This then required further change and adaptation. This theory is known as Agricultural Extension, which is the the synthesis and incorporation of economically sound research and development into agricultural businesses.” (Wellington, 2020). CHANGE IN CONDITIONS OVER TIME

SIMPLIFIED BIOD IVERSIT

30% DECLINE IN AVER AGE WINT BETWEEN 1895 - 2016 ER RAINFALL

1895

RAINFALL DEFICIENCES: April 2018 - April 2020 RAINFALL PERCENTILE RANKING Serious Deﬁciency Severe Deﬁciency

NATURAL SALT ACCUMULATION

1950

1835

Lowest On Record

EQUILIBRIUM

ACCELER

RAINFALL (absorbs salt on the surface) NATIVE VEGETATION (deep rooted perennials)

PREVAILING WINDS

OCEAN

SALT INLAND AUS.

Salt is stored in unsaturated soil profiles TOP SOIL

STORED SALTS (subsoil)

SALT is mobilised by rising water table

GROUNDWATER TABLE

SURVEYORS RECOGNISED THE GREAT SOUTHERN AS PRIME LAND FOR PASTURE AND AGRICULTURE

UP TO 85% OF NA FOR AGRICULTUR

A REGIONAL CONTEXT ESTABLISHMENT OF AGRICULTURAL PRACTICES

Early explorations of this land by John Septimus Roe found minimal fresh water sources, continuous salt water systems in the form of pools and perrennial streams, which is known as a chain of saltwater ponds. Simultaneously, areas close by were rich in grasses and tree species, which indicated soil and loam profiles of exceptional quality. A unique situation, whereby dryland farming is not and can not be facilitated by freshwater systems as salt was always present. In an area deemed excellently suitable for sheep grazing, the need for fresh water to sustain them was vital, and so, the clay-based, square dam was devised to capture ground run-off (Hercock, 2014).

Y UCTIVIT D PROD ndity) O O F D ASE p fecu - INCRE of shee

LTURE er rates AGRICU erage yeilds/high

(higher

DRYLAND SALINITY

2020

RATED LAND CLEARING

1990

2016

AGRICULTURAL EXTENSION

RE-PLANTING OF NATIVE VEGETATION WORKING TO LAND CAPABILITIES

AGRICULTURE AND PASTURE (shallow rooted annuals) Increased runoff prone to waterlogging CONCE NTRATED SALT

Rising groundwater table

ATIVE VEGETATION WAS CLEARED RE (BETWEEN 1950-1980)

HIGHER GROUNDWATER TABLE

DRYLAND SALINITY INCREASE HAS LEAD TO A LOSS OF 2 MILLION HECTARES OF PREVIOUSLY ARABLE LAND

Gradual lowering of groundwater table

PRECISION LAND MANAGEMENT PRACTICES CONTINUE TO BE IMPLEMENTED TO MAINTAIN FARM ECONOMICS AND MITIGATE SALINITY

A REGIONAL CONTEXT A HYDROLOGICAL CONUNDRUM

The chain of ponds in the Great southern are a part of an ancient salt river system, and while salty soil profiles and waterways are unforgiving to cereal pastures, adaptability and tolerance of livestock and native vegetation allows for higher farm productivity if applied correctly. Whereby different parts of the land are utilised for various farming processes. As salt is an undeniable characteristic of this landscape, working with it in this design, in connection with dam typologies can have positive effects on farming practices and value.

A HYDROLOGICAL CONUNDRUM No adverse effects of animals/stock between 0-4000mg/L

Mature sheep (Wethers) productivity wonâ&#x20AC;&#x2122;t be affected between 4000 - 10000mg/L

LIVESTOCK

Sheep: weaners, lambs, pregnant condition and production will decline at approx. 6000 mg/L

VEGETATION

FRESH WATER

MARGINAL

LESS THAN 500mg/L

500-1500mg/L

Standard cereal, canola, legume crop vegetation tolerant of less than 500mg/L

BRACKISH

1500-5000mg/L

Deep rooted perennial Natives between 2300-4500mg/L - Acacia (9 species) - Allocasuarina (2 species) - Eucalypt (36 species) - Melaleuca (13 species) Pasture - Trifolium (clover) (2 species)

Mature sheep (Wethers) condition and production will decline between 10,000-13,000mg/L

HYPERSALINE

SALINE

more than 50, 000mg/L

more than 5000mg/L Deep rooted perennial Natives between 4500-9600mg/L - Acacia (9 species) - Casuarina (2 species) - Eucalypt (8 species) - Melaleuca (6 species) Pasture - Trifolium (clover) (2 species)

SEA WATER 35, 000mg/L

Deep rooted perennial Natives between >9600mg/L - Acacia (9 species) - Casuarina (2 species) - Melaleuca (2 species) Pasture/Shrubs - Atriplex (10 species) -Trifolium (clover) (1 species) - Paspalum vaginatum - Pucinellia ciliata

STOCK WATER REQUIREMENTS Two sheep per acre (40-50kg ewe) SALTBUSH 14L per day LUCERNE HAY

9L per day

HIGH PROTEIN STUBBLES

6L per day

DRY FEED

4L per day

Wethers drink from a three-walled dam. Source: Dept. of Primary Industries and Regional Development, 2020

A REGIONAL CONTEXT AGRICULTURAL ADAPTATION TO FRESH WATER SCARCITY

Current dam typologies, which are the primary fresh water providers to stock, have not changed in the 150 years of farming in the area. While there are variations, their requirements and limitations are shared. The most common type of dam is the rectangular/square excavated dams with three or four walls. This is the only type found on our farm. They are built to ensure a two year supply of water for stock with no rainfall based on a 4ft annual evaporation rate. However, with changing climatic conditions and the existing landscape issues these prerequisites are fast becoming outdated.

“A dam is a depression in the ground that may, or may not, hold water” - Michael Batchelor DAM TYPOLOGIES RECTANGULAR AND SQUARE EXCAVATED DAMS WITH THREE OR FOUR WALLS

TURKEY NEST DAM

emergency spillway slope of catchment Rela�vely ﬂat terrain

embedded salts below deepest point of dam

GULLY-WALL DAM

RING DAM

Rela�vely ﬂat terrain

slope of catchment

embedded salts prevent deep excava�on

A CRITICAL LANDSCAPE THE FARM AS IT IS - ENVIRONMENTAL CONDITIONS

Understanding the regionâ&#x20AC;&#x2122;s landscape and practice processes is essential to agricultural extension, but the application of my design will occur on the area I know so well, our farm. Originally named Tassajara but now known as Finisterre, it sits on gently undulating topography varying from 338 metres to 280 metre of predominantly sandy loam duplex with with some saline soils.

MIXED PRODUCTION SYSTEMS

A CRITICAL LANDSCAPE MIXED PRODUCTION SYSTEMS

“When favoured by economic conditions, many farmers seem prepared to accept the higher risk associated with continuous cropping systems, presumably the expectation of greater financial return and perhaps for the ‘simplicity of specialisation” -Hacker et al., 2009

LAMB MUTTON

Value (A$ million)

THE VALUE OF SHEEP MEAT EXPORTS

Fresh water efficiencies are the foundation to successful farming; livestock and broadacre. When looking at dams, water needs and landscape capabilities, none exist in a single vaccuum so the combined factors are what determines a successful design output that can function across a number of thresholds.

2007 2008 2009 2010 2011 2012 2013 2015 2016 2017 2018 2019 2020

Value (A$ million)

THE VALUE OF WOOL EXPORTS FOR WA

Year

2007 2008 2009 2010 2011 2012 2013 2015 2016 2017 2018 2019 2020

Value (us$/T)

WORLD WHEAT PRICE

Year

2007 2008 2009 2010 2011 2012 2013 2015 2016 2017 2018 2019 2020

Value (us$/T)

WORLD BARLEY PRICE

Year

2007 2008 2009 2010 2011 2012 2013 2015 2016 2017 2018 2019 2020

Year

A CRITICAL LANDSCAPE WATER SYSTEMS ON SITE

C. A. B.

CURRENT BENEFITS/FUNCTION:

- Existing vegetation acts as natural water filter and provides habitat CURRENT LIMITATION/FUTURE OPPORTUNITY: - Its function as a dam collcting runoff is minimised because of vegetation and high evaporation rates

CURRENT BENEFITS/FUNCTION: - Minimal function, fenced habitat

CURRENT LIMITATION/FUTURE OPPORTUNITY: - High amounts of underground salt water, unarable land

CURRENT BENEFITS/FUNCTION:

- Minimal pastures and good catchment zone allow for maximum capture potential CURRENT LIMITATION/FUTURE OPPORTUNITY: - Little/no environmental contribution, is susceptible to evaporation, close proximity to salt scolded zone

LEGEND MINOR GULLIES ROADED CATCHMENT DAM DRAIN SALT SCOLD Embedded salt has been activated and brought to the surface on previously arable land

SITE INTERVENTIONS Dams size of / or exceeding 3000mÂ³ with retrofit and implemention of broader systems

A. House Dam - High vegetation zone/Prioritised for grazing

Desalination Plant - Nonarable land in close proximity to pasture/crop paddock

C. West Dam - Crop and Pasture rotation paddock

0.5

1.0 Km

COLLABORATIVE INPUT INTERVIEWS WITH LOCAL REPRESENATIVES AND FARMING STAKEHOLDERS

The theory supporting Point-of-Practice-Integration, which highlights the difficulties of agricultural extension (Hacker et al.,2009), in cereal-livestock zones was experienced first hand through my explorations. The most valuable suggestions, design explorations and considerations came from the farmers themselves and on-ground knowledge, not from external, institutional environments. Additionally, their most valuable source of information is from each other, where experience is prioritised over new policies. However, as technologies develop and the threat of disaster imposes on farmers, they will look to adapt, as they always do. Designers and governing bodies have the potential to elevate rather than impede on what farmers are already doing to ensure future practice.

Peter Rundle MLA, Member for Roe and Farmer, Katanning WA “Water is a real issue - of the 12 water deficiencies that have been declared in WA, 11 are in my electorate.../...there is an opportunity for new ideas as something needs to change.”

Lindsay Adams, Water Protection Sector at Netpro, QLD “Dam covers aren’t widely adopted for two reasons, 1. they can be costly and 2. people will only do it when they get desperate and then it rains so people ‘forget about it’.../... Where we are, we are in a five year drought and it’s getting so bad people are carting water.../...I think the future lies in dams being built to be covered and the canopies can minimimise evaporation by up to 90%.../...It comes down to how badly the farmers want water.”

Paulus des Anges, Earth, Water and Infrastructure, VIC “Dam covers seem like the most viable option to prevent evaporation, cost is a part of it but it’s also how people assess the benefit - in agriculture you may not get the same thorough approach compared to say, water authorities or mining operations but every year water is more of an issue so that may be about to change.../...manufacturing costs are becoming less, making it more feasable.”

White Clay Dam. Source: Prue Batchelor, 2020

Michael Batchelor, second-generation Farmer (my Father), Tambellup WA Since I have been farming there has been a significant decrease in rainfall and there is no surplus in fresh water. We have had to adapt and innovate, producing the kinds of crops we do now, we couldn’t have done 50 years ago on the rainfall we get now.../...farmers in this region are the most productive dryland farmers in Australia but I was unaware of how much we actually lose to evaporation, we say 4ft per year but when you convert that to a full dam its nearly 40% of the water.../...there is no silver bullet to our water problems but something has to be done.”

Scott Anderson, third-generation Farmer, Tambellup WA We don’t necessarily have problems with salt but everyone has problems with evaporation, if a dam cover could save 2m of evaporation per year we would have full dams right now.../...I doubt farmers would plant more trees [if all dams were full], it would just mean we don’t have to cart water in Summer or have to sell large amounts of stock. There is no real incentive to plant trees now unless the ground is salty.../...a big demand in dam covers would probably drive the price down.../...I definitely value other farmer’s opinions. Very rarely will I listen or trust a salesman for something they want to sell because so many people have been let down in the past.”

Jedd Herbert, fourth-generation Farmer, Tambellup WA We aleady had a salt water bore which could be drunk by some stock but was too salty for spraying and lambs so we put it [desalination plant] in with a solar pump and in Summer we can get up to 18,000L of drinkable water per day.../...You can build as a big a dam as you want but if you can’t fill it, it’s a waste of time. We chose a desalination plant because we already have water [salt] so we might as well work with it.../We got on to it because my bank manger’s parents had put a desalination plant in and that’s what spurred the idea on and I started to look into it. Knowing that someone else has done it gives you confidence to try it.”

COLLABORATIVE INPUT AGRICULTURAL PRECEDENTS FOR IMPROVED FRESH WATER EFFICIENCY

The use of precedents and existing agricultural application is very influential in establishing an innovative design outcome. Farmers are already privy to problems and issues with their land and are continually trialling the application of new processes. However, there is no one single solution to improving fresh water managment on the farm. I believe utilising aspects of all of these applications in very specific areas of my site could achieve a design intervention targeting fresh water availability and utilisation as well as improved environmental condition and farm productivity

SALT MANAGEMENT

NORTHAM, WA

TAMBELLUP, WA

DESALINATION

SALTBUSH GRAZING

Reverse osmosis (RO) improve water self sufficiency - cost $20k - $40k, from bores produce brackish water, water from off farm sources are limited, need safe place to dispose of the reject water

Salt tolerant vegetation planted and utilised for Summer stock grazing - saltbush grazing requires more fresh water for stock, grazing needs to be monitored to minimise damage

MARAS, PERU

EVAPORATION POND

REVEGETATION

Shallow artificial salt pan designed to extract salts from sea water or other brines - water is drawn out through natural evaporation which allows the salt to be subsequently harvested

Using endemic, deep rooted species to rebuild the soil of disturbed land - manages salinity levels but recovery may be slow, no productive value for farmers, salt movement offsite is unlikely to decrease

EVAPORATION MANAGEMENT

CLARE VALLEY, SA

MOSSGROVE, NSW

NSW

DAM COVERS

WIND BREAKS

NSW DAM GUIDANCE

Impermeable barriers that float or are suspended on top of the water surface (60-90% effectivenesslimited commercial availability, cost, durability, installation and wind resistance

Tree windbreaks planted near dams provide some protection from (wind) evaporation - long term establishment, can’t be planted close to embankment, may hinder dam cleaning

A farm dam providing habitat for native species to increase biodiversity value - the value of ground cover and vegetation limits the productivity available to cropping, limited effectiveness for high evap. rates

GRADE BANKS

KEYLINE PLOUGHING

CONTOUR PLOUGHING

Intercept and divert surface water run-off into storage or waterways, to limit soil erosion - Limits efficiency of precision cropping, high maintenance where livestock and machinery cross

Capture water and move it across the landscape using “Keylines” (to enhance/activate topsoil for prodctive land - high cost/input, restores aquifers and subsurface flows rather than surface water for stock

Ploughing and/or planting across a slope following its elevation contour lines (minimises top soil loss and soil erosion) - run-off into dams is minimised, where rainfall is minimal and evaporation is high, runoff is required

EROSION MANAGEMENT

MONTGOMERY, USA

RADICAL PRACTICE - WATER

PITHARA, WA

MULLOON, NSW

BOONDI ROCK, WA

GROUNDWATER DRAINAGE

NATURAL SEQUENCE FARMING

IMPERMEABLE SURFACE DRAIN

Land is dug away to groundwater to reduce levels, eliminate waterlogging and move excess water away from productive land - impact on downstream environment and flood risks

Slow flow in creeks with “leaky weirs” that force water back into bed and bank of creeks - not as applicable to landscapes with saline water systems, Government restrictions

Use of large granite slabs into rock-lined channel directing all rainfall into dam - on site materials deter replication, no allowance for vegetation or infiltration

DESIGN STRATEGIES ENVIRONMENT VS ECONOMICS; UNCOVERING RESISTANCE By working across a range of scales, utilising local knowledge and uncovering regional specificities, it’s clear that the process of design and establishing design applications is not a linear process. There were multiple factors that had to be considered before undertaking and producing this design. Water availability as the underlying foundation coupled with attitudes of farmers, policies and incentives, government attitudes, available resources, potential of integration, observation, time, value, economies of scale and sustainability provided a narrative to enable further actions to be taken. Improved water efficiencies, mitigation of salinity and enhanced biodiversity have been synthesised with time, trials and thresholds to provide a design solution to fresh water management in the Great Southern of WA. Presenting unseen design contributions and relationships is central to larger futures as well as the design and landscape. Drawing on inspiration from Anuradha Mathur, Dilip da Cunha and James Corner, ‘mapping’ as a creative process uncovered the realities and potentials of the site on a micro and macro level, enabling a diverse and optimistic consequence (Dodge et. al, 2011).

“What distinguishes the map from the tracing is that it is entirely oriented toward an experimentation in contact with the real. The map does not reproduce an unconscious closed in upon itself; it constructs the unconscious.” - Gilles Deleuze and Felix Guattari, 1987

DESIGN STRATEGIES DESIGN CONSIDERATIONS AND EXPLORATIONS

DEEPENED CONTOUR BANKS Considerations Working with existing landscape conditions High rate of evaporation - not guaranteed for stock (high time input by farmer) Disruptive to productivity of paddock Advantages Use of water tolerant/riparian vegetation to enhance biodiversity

TANK Considerations Effectiveness - requires runoff from catchment to hold water Cost - implementation underground/above ground has high costs with minimumum long term offsets Advantages All water is retained (no loss of water to evaporation)

DOUBLE DAM Considerations Cost - dam construction costs based on earth moved per m3 Capability - bulldozer capabilities are limited to certain slope Salinity -will limit depth of dam

Advantages Minimising surface area to minimise evaporation

DESALINATION PLANT Considerations Waste water requires clean/safe disposal of hypersaline reject water Cost - Large output in the short term (offset in the long term) Advantages Climate independent - water supply already exists Constant supply of water Transportable Salt as a bi-product to contribute to mixed farming ventures

DAM COVER Considerations Multiple variations - some require additional infrastructure Cost - high cost to implement Minimal environmental contribution Advantages Minimises evaporation loss Minimises/eliminates algal growth

IMPERMEABLE CATCHMENT Considerations Environmental conditions impermeability coud have negative effects and reduce productivity of catchment area Vegetation opportunities - replicate â&#x20AC;&#x2DC;strawberryu farming techniqueâ&#x20AC;&#x2122; of covered mounds Advantages Maximise runoff into dams

DESIGN STRATEGIES DESIGN CONSIDERATIONS AND EXPLORATIONS I tested the technical outcomes of an impermeable cover on a roaded catchment. I wanted to explore the environmental limitations and opportunities of impermeable covers. While impermeability ensures maximum run-off potential it has little environmental contribution, short-term and long term. With the addition of vegetation on the central avenue, there is a positive ecological offset to the liner. However, the integrity of the linerâ&#x20AC;&#x2122;s run-off capturing capabilities may be comprimised. Mimicking the design of covered, mounded strawberry farms, the possibility for vegetation development situated on the highest mound of the plastic sheeting is not only viable but also beneficial, providing additional habitat and shade cover. With the same water flow rate and time, the amount of runoff being captured by the tree holes has minimal implications on total runoff into the dam in comparison to no trees at all I made a 1:100 model catchment out of clay from the site. Tilted in the 1:32 slope (approx 1.5%) I was able to add water from a hose to simulate rainfall and consequently flow rate down the catchment.

Test. 1 Roaded Catchment with liner and no vegetation

Test. 2 Roaded Catchment with liner with vegetation

DESIGN STRATEGIES CRITICAL REFLECTION: MATERIALS Through explorations and interviews, covering dams is the most efficient and short-term solution to improved fresh water management. However, there are many variations that had to be considered for best application in this design. Dam covers provide very little environmental contribution in the long term so its application, under the guise of the outlined design considerations, requires further exploration to achieve a positive ecological offset. This could include a combination of design interventions that complement each other and elevate the landscape processes as a whole.

EVAPORATION Mitigation Exploration - DAM COVERS COVER TYPE

COVER NAME

Shade Structure

Flexanet

Shade Structure

NetPro

Floating Cover

Hexa-Cover

Modular Covers

AgFloat (recycled tyres & styrene foam)

Chemical Monolayer Covers

Aquatain

Vegetation

Free-floating Water Plants

KEY ADVANTAGES

ESTIMATED EVAPORATION SAVINGS

The structure is long lasting and the cover is not affected by changing water levels

By 75 - 84%

Uknown

The structure is long lasting and the cover is not affected by changing water levels

By 80 - 85%

$20-$25 per sqm *based on 100sqm install

Heat reflective, self-protecting in high winds. The cover is also suitable for all storage sizes and easily installed by customer

By up to 90%

$45 per sqm inc. frieght to WA

Made from recycles materials, durable and long lasting, little maintenance

Very low initial setup costs and relatively low ongoing maintenance costs (silicone-based liquid)

Flowers and foliage help shade the dam effectively without impeding flow of water and minimise risk of algae blooms (eg water lillies)

Estimated 70-80%

Purchase price reported to be less than other available products

Around 50%

$18/litre with an application rate of $6/ha

Unknown

Varies

WATER STORAGE

COST

CRITICAL REFLECTION: VEGETATION The specific vegetation chosen across the interventions is based on their biphysical cababilities. The species need to perform in a landscape where their contribution is constantly evolving. The ‘House Dam’ species have been selected for their drought tolerance and known performance on the site. Not only do they provide additional aesthetics to the bare catchment site, they will provide a patch of habitat for birds and insects, which will contribute to the biodiversity of the area. The forage shrubs and salt bush have been selected for short term feed options for stock and concurrently, their soil improvement capabilities over time.

HOUSE DAM

VEGETATION AS ADDITIONAL HABITAT AND CREATING A ‘PATCH’ IN A MATRIX OF DRY COUNTRY

Acacia acuminata Endemic species Nitrogen fixing Salt/drought tolerant Host to Sanatalum spicatum

Corymbia ficifolia Endemic species Drought tolerant Bird, lizard, insect attracting

Sanatalum spicatum Endemic species Hemiparasitic Drought tolerant Bird, lizard, insect attracting

WEST DAM ALLEY FARMING WITH FORAGE SHRUBS

Atriplex spp.

Cytisus proliferus Tagasaste

Saltbush

Atriplex nummularia

Leucaena

Native

Exotic

Increase total feed production and animal carrying capacity on difficult soils

Supply green feed in Summer and Autumn

Aid in controlling wind erosion

Use more water than annual pastures and reduce recharge to the groundwater

Drought-tolerant

Cytisus proliferus

Leucaena leucocephala

Grown mainly on salt-affected land

Drought-tolerant Requires hard grazing or cutting to prevent flowering - maintenance

Supply green feed in Summer and Autumn Accelerates soil acidification Tropical, fast-growing tree legume High cost of establishment High rate of establishment failure due to weed competition and insect predation

Grows in pale, deep sands

“where crop production is water-limited, the best strategy is to segregate trees from crops rather than integrate them.../...In Australia the choice is stark: increase leaf area in agricultural landscapes on a permanent basis and live with some degree of trade-off (economically) or accept increasing levels of salinity”- Lefroy, 2002 NATURAL SYSTEMS BALANCE

SOIL WATER IMPROVEMENT

DESIGN STRATEGIES TIMELINE OF IMPLEMENTATION

HOUSE DAM: A FAST SOLUTION TO FRESH WATER COLLECTION DESIGN STRATEGY: EVAPORATION MITIGATION AND DAM WATER COLLECTION

The idea of a dam cover has been used with the application of Hexa-cover discs. Made of recycled plastic and simply installed, this ‘cover’ has the ability to minimise evaporation by 90% and save 1.1 million litres of fresh water annually for this particular dam. As reduced rainfall is an ongoing consideration, dam covers will only be effective if there is water in the dam. By taking advantage of site conditions, the ‘w’ roaded catchment drain has been covered with impermeable sheeting to ensure maximum runoff and weighted with recycled farm tyres. This area was neither arable nor used by stock so short-term productivity has not been compromised. Additionally, endemic species are planted on the highest point of the central avenue and the lowest point of the outer slopes to create habitat for bird species, provide wind breaks as evaporation mitigation and contribute to soil rehabilitation and groundwater control. With a primary function of short-term water collection and storage, the site still maintains maximum livestock efficiency, but its ongoing processes have a permanent contributions.

HOUSE DAM: A FAST SOLUTION TO FRESH WATER COLLECTION DESIGN OUTCOME

Corymbia ﬁcifolia

OUTER SLOPE PLANTING

Santalum spicatum Acacia acuminata

RE-USED TYRES AS WEIGHTED

HDPE PLASTIC LINER

CENTRAL AVENUE PLANTING

-Minimal impairment to runoﬀ collec�o - Wind break as evapora�on preven�on - Soil rehabilita�on

-Se�ng up a ‘patch’ in a matrix of dry country -Wind break for evapora�on preven�on

scale 1:200

10m

Eucalyptus wandoo

on n

OUTER SLOPE PLANTING

-Se�ng up a ‘patch’ in a matrix of dry country - Protec�on for stock - Na�ve habitat

STANDARD WIRE FENCING - Barrier to liner damage - Aids in vegeta�on establishment

HOUSE DAM: A FAST SOLUTION TO FRESH WATER COLLECTION DESIGN OUTCOME

CENTRAL AVENUE PLANTING

IMPERMEABLE COVERED ROADED CATCHMENT

STOCK HABITAT

HOUSE DAM: A FAST SOLUTION TO FRESH WATER COLLECTION DESIGN OUTCOME

COVERED ROADED

STOCK HABITAT

STOCK ACCESS

HEXA-COVER CLAY CORE

CLAY DAM BANK

WHITE DAM: NOT A DAM AT ALL - DESALINATION DESIGN STRATEGY: WORKING WITH SALT

The next intervention moves beyond retrofitting a dam and positions the farm towards long-term fresh water management that is climate independent. Glorifying the natural salt water systems that are on the lower topography of the farm, a desalination plant has been implemented to capitalise on a water supply that already exists. Adjacent area has been designed as an evaporation pond. Not dissimilar from the Turkey Nest dam typology, this concept ensures there is an environmentally safe disposal point for the hypersaline water (produced by the plant) so it doesnâ&#x20AC;&#x2122;t re-enter the subsoil. Reject water is drawn out through natural evaporation leaving the salt on the surface. Harvesting the salt bi-product provides an additional element to mixed farming production systems, a diversifying strategy that may contribute to reduced risk of specialised farming in the face of climatic changes and uncertainty.

WHITE DAM: NOT A DAM AT ALL - DESALINATION DESIGN OUTCOME

Atriplex nummularia

PRODUCT WATER TANK SALT WATER BORE FRESH WATER - Pumped to troughs/tanks across farm

scale 1:200

10m

DESALINATION PLANT

-Reverse Osmosis of saline ground water - Solar powered

Exis�ng vegeta�on

REJECT WATER - Pumped to evapora�on ponds

EVAPORATION PONDS - Shallow, ar�ﬁcial, clay pond - Prevents concentrated salt reject water from re-entering subsoil - Salt harves�ng poten�al

WHITE DAM: NOT A DAM AT ALL - DESALINATION DESIGN OUTCOME

DESALINATION PLANT

EVAPORATION POND SALT BI-PRODUCT

SHALLOW CLAY BASE

WEST DAM: A LONG TERM COMMITMENT TO IMPROVED FARM SYSTEMS DESIGN STRATEGY: ONE LANDSCAPE AND THE PRODUCTIVE VALUE OF CHANGE

The third design has been implemented using small-scale interventions that maintain agricultural trends and enhance farm productivity in the short-term and long term. The application of the Hexa-cover discs for evaporation mitigation is complimentary to the larger process occurring further down the site. Sited in the spillway zone below the West Dam and above the salt flat of the Desalination plant, alleys separated in 45m increments have been planted with Cytisus proliferus and Atriplex nummularia. The vegetation is essential for water dispersal along the contours as opposed to down the gully, which will aid in preventing water logging in the lower salt zones. Additionally, the deep rooted Atriplex will contribute to lowering the groundwater table over time. The nitrogen fixing root nodules of the Cytisus improve soil quality and provide mineral nitrogen to the adjacent crops. Both the Cytisus and Atriplex are forage shrubs and provide green pasture for stock in the Summer and Autumn months in an area of paddock otherwise subject to traditional grazing rotation as well as becoming a provision of habitat for bird species. 45m alleys ensures farm machinery capabilities arenâ&#x20AC;&#x2122;t compromised in any way when a crop rotation occurs. This reworking of surface and groundwater reshapes relationships on the farm more widely. Rather than viewing each farming process separately, they are integrated to form one system, which additionally corresponds to the previous two sited locations and subsequent design interventions.

WEST DAM: A LONG TERM COMMITMENT TO IMPROVED FARM SYSTEMS DESIGN OUTCOME

FORAGE SHRUBS

- Tagasaste increase total feed producï¿½on and animal carrying capacity - Use more water than annual pastures and reduce recharge to the groundwaters

SUMMER - AUTUMN scale 1:200

10m

Cytisus proliferus

- 45m alle farm machin

- Crops have

WINTER - SPRING

scale 1:200

10m

ALLEY PLANTING

- Aid in controlling wind erosion - Provison of habitat for bird species - Nitrogen ﬁxing roots improves soil quality over �me - Green feed supply in Summer months

Hordeum vulgare (annual crop) Cytisus proliferus

ALLEYS

ey between shrub plan�ng to allow for nery capabili�es (Seeder = 20m, Boom Spray = 36m) e minimal root compe��on with forage shrubs

MOUNDING

- slows run-oﬀ in rain events and protect low lying areas from waterlogging - natural distru�on of water along contours for uptake by vegeta�on

WEST DAM: A LONG TERM COMMITMENT TO IMPROVED FARM SYSTEMS DESIGN OUTCOME

Cytisus proliferus

ANNUAL CROPS

STOCK NUTRIENTS

MINERAL NITROGEN

ROOT NODULES

DECOMPOSITION

BIOLOGICAL NITROGEN FIXATION

ALLEY PLANTING

SOIL MICROBES

Atriplex nummularia

Cytisus proliferus

SL 300m

SL 298m

SALT TOLERANT VEGETATION (FORAGE SHRUB)

- Gradually lower water table and improve produc�vity of previously un-arable land

E SOILS TS - SALIN

OSI

DEP ALLUVIAL

scale 1:500

50m

SUITED TO SAN

- Nitrogen ﬁxing root

SHORT TERM

80% WATEREVAPORATION SAVED FROM 6 MONTHS OF ADDITIONAL GREEN PASTURES FOR STOCK 460 PERMANENT, NITROGEN FIXING SHRUBS TO IMPROVE SOIL QUALITY

LONG TERM

NATURAL SYSTEMS

APPROACH TO SALINITY MITIGATION WITH DEEP ROOTED, NATIVE SALT BUSH Exis�ng Vegeta�on

N SL 302m

WEST DAM

ND (FORAGE SHRUB)

t nodules

THE ‘WEST DAM’ AND SURROUNDINGS DESIGN WILL PROVIDE

Y AND E-S

- Addi�on of ‘Hexa-cover’ discs

IT TER Y LA TIAR TER

CONCLUSION

The different ‘designs’ for different dams or locations highlights the variation across the landscapes. There is not one single outcome; it’s a compilation of factors and options combined to achieve the greatest synergy between productivity, resilience and regeneration. A productive landscape will only remain so, if all elements are balanced. The design examples show how farming in this region has the capacity to adapt and upgrade processes without compromising productivity but also, provides a vision of integrated processes and natural systems, which could stabilize fresh water resources both now and in the future. Despite decreased rainfall and impending salinity issues, this region is magic and the eternal optimism of my family and all farmers is what carries it on. Farmers are adaptive, and their ability to work with the landscape to make a living is a skill we as landscape architects should deeply value. By implementing experience of farmers, knowledge of designers and innovation of science, we can continue to work with the landscape and ensure its longevity.

“Much work will need to be done by all - farmers, their communities, and government institutions, to enhance enablers, and overcome barriers to implementation, in order to support the significant changes to come.” McWilliam, 2018

Wendy

REFERENCES

THEORY

Cunningham, D. and Drewer, S. (2011). Farm dams - a guide to siting, design, construction and management on Eyre Peninsula. Rural Solutions SA.

Halse, S.A, Ruprecht, J.K and Pinder, A.M (2003). Salinisation and prospects for biodiversity in rivers and wetlands of south-west Western Australia. Australian Journal of Botany. 51. 673688

Coorong District Council. (2016). Water Harvesting and Lined Catchemnts. Department of Agriculture and Food (Oct 1, 2020). Groundwater desalination on farms in Western Australia. https://www.agric.wa.gov.au/ water-management/groundwater-desalinationfarms-western-australia Department of Agriculture and Food (Aug 14, 2020). Salinity tolerance of plants for agriculture and revegetation. https://www.agric.wa.gov.au/ soil-salinity/salinity-tolerance-plants-agricultureand-revegetation Department of Agriculture and Food (Oct 28, 2020). Season 2020 - seasonal and management information for Western Australian Farmers. https://www.agric.wa.gov.au/dry-seasons-anddrought/season-2020-%E2%80%93-seasonaland-management-information-western-australianfarmers Department of Agriculture and Food (May 1, 2018). Soil Water Repellence - the science. https:// www.agric.wa.gov.au/water-repellence/soil-waterrepellence-science

Hercock, M. (Ed.) (2014). The Western Australian Explorations of John Septimus Roe 1829-1849. Hesperian Press. Lefroy, E.C (2002). Forage Trees and Shrubs in Australia. Rural Industries Research and Development Corporation. Lefroy, E.C (2001). The influence of tagasaste (Chamaecytisus proliferus) trees on the water balance of an alley cropping system on deep sand in south-western australia. Crop and Pasture Science. 52(2). 235-246 Mungai, N. (2014). Sustaining native biodiversity through conservation and nature-firendly farming. Rural Society. 23(2). 198-206 Stanton, D. (2005). Farm dams in Western Australia. Department of Agriculture and Food, Western Australia. Bulletin 4609 Wellington, M. (2020). Towards effective extension services in Australia. Agricultural Science. 31(2). 100-109

Department of Agriculture and Food (Oct 5, 2020). The Western Australian Sheep and Wool Industries. https://www.agric.wa.gov.au/sheep/ western-australian-sheep-and-wool-industries

INTERVIEWS

Department of Agriculture and Food (Feb 10, 2020). Water Quality for Livestock. https://www. agric.wa.gov.au/livestock-biosecurity/water-qualitylivestock

Anderson, S. Personal Communication. Oct 16, 2020

Fernandes, A. (2018, Aug 7). Salinity, erosion fight and the sake of crop diversity sees volunteers help farmer plant 30,000 trees. ABC News. https:// www.abc.net.au/news/2018-08-07/volunteershelp-farmer-plant-30000-trees/10075616 Hacker, R.B, Robertson, M.J, Price, R.J and Bowman, A.M. (2009). Evolution of mixed farming systems for the delivery of triple bottom line outcomes: a synthesis of the Grain & Graze program. CSIRO Publishing. 49(1). 966-974

Adams, L. Personal Communication. Oct 18, 2020

Batchelor, M. Personal Communication. Aug 27, Aug 30, Sept 18, Oct 2, Oct 12, Nov 3, 2020 des Anges, P. Personal Communication. Oct 21, 2020 Herbert, J. Personal Communication. Oct 28, 2020 Rundle, P. Personal Communication. Aug 22, 2020