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Centre for Water Management and Reuse

An assessment of the drainage quality and quantity associated with recycled wastewater irrigation in an urban park

H a m i d e h N

• u

r i

PhD scholar and tutor University of South Australia

June 2013

Centre for Water Management and Reuse

Background

Of some concern is the nutrient leaching nutrient leaching from drainage into ground water that possibly percolates excess nutrient to the ground water table. This is even more critical when reclaimed wastewater throughout irrigation.

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Soil Water Balance (SWB)

A soil moisture budget tracks the inputs and outputs of water in soil.

Drainage Drainage (deep percolation) (deep percolation)

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Knowledge gap

Research work on Soil Water Balance of agricultural crops is well established. Little research has been conducted on this aspect for urban green space mixed plantings.

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Drainage, a component of SWB

Estimating drainage requires in-situ soil water collection from undisturbed soil which is quite challenging particularly in heterogeneous urban landscape environments.

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Why pan lysimeter?

Pan lysimeter is a sampler in a pan shape, without large side walls, that freely collects the drained water, measuring drainage volume and solute leaching simultaneously.

ADVANTAGES:

• low complexity design
• inexpensive to construct and install
• reduced disturbance of the soil in installation
• simple and cheap operation
• minimizes the surrounding matric potential

fluctuations and potential bypass flow

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Lysimeter installation

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Objective

Study the temporal variation of drainage rate and nutrient leachingin an urban park

Map of the urban park and lysimeter position

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Study area

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Quantity of drainage

• The volume of the drained water was recorded monthly and analysed.

Summer Winter Irrigation 198.67 Rainfall 37.44 157.36 Input water (irrigation + rainfall) 236.11 157.36 Volume of drainage 0.8 123.6

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Quality of drainage

2 4 6 8 10 12 pH Value Sodium Absorption Ratio (*0.1) EC Potassium (*0.1) Nitrite as N (*100) Nitrate as N (*100) Total Kjeldahl Nitrogen as N (*10) Total Phosphorus as P (*10) Ionic Balance

Comparison of leachate solute (ppm) from summer to winter

Winter Summer

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Outcomes & benefits

The risk of nutrient loading resulting from irrigation with recycled waste water was investigated. The outcomes showed a minimal impact from use of recycled waste water in terms of nutrient loading to the ground water for the study period.

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Thank y ou f or t he k i nd at t ent i on

Thank you for your kind attention