Water Cycle Infill Green Field Development

Instructions

The Truganina precinct has been adopted as part of the focus area for a recent Scenario Tool case study. The purpose of this case study is to consider how specific interventions of urban form and water servicing in greenfield development areas can support the delivery of integrated water management outcomes. The rapid transformation of Melbourne’s west is impacting on the water cycle of this region, and there is keen interest amongst government stakeholders to investigate how strategic changes to urban planning and development may help to resolve challenges the regional water balance is facing due to population growth and climate change.

The Truganina PSP describes the vision for Truganina and ensures the delivery of key local infrastructure to promote accessibility and community activity within the precinct. In this tutorial, we will use part of the Truganina PSP with the Scenario Tool to model the Water Cycle Model for the specified area of mixed land uses and quantify the potential reduction in water sourced from the water supply system as a result of the implementation of various alternative water sources. In total, four scenarios will be produced: the baseline conditions detailing the current state of pre-developed Truganina, a business-as-usual case reflecting the proposed development of Truganina owing to existing planning policies and schemes, and three intervention scenarios that each feature different alternative water source systems.

Truganina - Urban Water Cycle

Model Setup

  1. Before beginning, use this Dropbox folder to access the GIS data employed as part of this seminar

  2. To start, navigate to the Scenario Tool website and log in using your registration details (otherwise register for the tool and then proceed to log in)

  3. At the project dashboard, create a new project, name it, and set the region to Melbourne

  4. Select the land surface temperature and water balance modules

  5. Upload the boundary file that is part of the GIS dataset previously referred to

  6. Submit the project to initialisation it

  7. Upload the remaining GIS files after reaching the project dashboard

Scenario 1 - BAU

This scenario represents the business-as-usual approach, incorporating a mix of different land uses and serving as the case that will be subjected to the implementation of alternative water source schemes.

Note

The nodes, their parameters and the GIS layers used with them have been informed from a combination of relevant literature and government authority input. As part of this seminar, the specific documentation for each node should be read to gain an understanding of its function and the resources used to calibrate it.

To prepare the business-as-usual scenario, begin with the ‘Clear Area’ node and add ‘Residential’ node, using the ‘residential.geojson’ file as the area of effect and the parameter set below; then, follow the relevant table to set up the rest of the scenario. urban_form_bau shows the outputs for the urban from and land surface temperature accross the case study area

Note

The Urban From node refers currently to the residental node which will be renamed

Parameter

Residential

Light Industrial Zone

Educational Zone

Workflow Node

Urban Form

Urban Form

Urban Form

Area

Residential

Industrial

School

City block width

80

180

10000

City block length

240

120

10000

Street offset

8

5.25

0.1

Parcel width

14

54.75

10000

Parcel length

31

42.8

10000

Building height

6

7.5

7.5

Site coverage

0.6

0.45

0.2

Residential units

1

2

680

Hardstand fraction

0.5

0.82

0.63

Garden fraction

0.8

0.8

1.0

Tree canopy diameter

7

7

7

Percentage of lots with trees

0

0

0

Number of trees per lot

0

0

0

Street tree spacing

13

13

13

Workflow Node

Create Lot

Create Lot

Create Lot

Area

Recreational Reserve

Road

Other Pervious Area

Employee/student count

0

0

0

Tree Cover

0

0

0

Water Cover

0

0

0

Grass Cover

0

0.25

0.9

Irrigated Grass Cover

1.0

0

0

Roof Cover

0

0

0

Road Cover

0

0.5

0

Concrete Cover

0

0.25

0.1

_images/urban_form_bau.png

Fig. 2 Urban form and Land Surface Temperature for the BAU scenario

Scenario 2 - RWHT

The first intervention scenario centres on rainwater harvesting, with residential lots now gaining access to rainwater for non-potable and out door reuse. Therefore, the residential properties need to be assigned a new lot template.

  • Parent scenario: BAU

  • Workflow node: Lot Template (This will create the lot template with the ID 2)
    • Area: Residential

    • fraction of lots: 1

    • All other values are default

  • Workflow node: Lot Scale Storage
    • Area: Residential

    • Template ID: 2 (This will be updated to a drop down)

    • Inflow: roof runoff

    • Demand Priority 1: non potable demand

    • Demand Priority 2: outdoor demand

    • Demand Priority 3: -

    • Storage Volume (m3): 5

_images/lot_template_ids.png

Fig. 3 Lot template IDs in the catchment.

Scenario 3 - Water Recycling

The first intervention scenario centres on a water recycling system, which collects wastewater from the entirety of the case study’s population and supplies it as reclaimed water to all industrial lots. To do so 2 sub catchments are added to the model. The first sub catchment will collect waste water from the residential area and the 2nd will define the industrial zone as reclaimed water zone.

  • Parent scenario: BAU

  • Workflow node: Sub Catchment (This will create the sub catchment with the ID 10)
    • Area: Residential

    • Stream: sewerage

  • Workflow node: Sub Catchment (This will create the sub catchment with the ID 11)
    • Area: Industrial

    • Stream: potable demand

  • Workflow node:Sub Catchment Storage
    • Area: Case study area

    • Inflow ID: 10

    • Demand ID Priority 1: 11

    • Demand ID Priority 2: -

    • Demand ID Priority 3: -

    • Storage Volume: 500

Scenario 4 - Water Recycling + RWHT

The second intervention builds off the first, with residential lots now gaining access to rainwater for non-potable reuse.

  • Parent scenario: Water Recycling

  • Workflow node: Lot Template (This will create the lot template with the ID 2)
    • Area: Residential

    • fraction of lots: 1

    • All other values are default**

  • Workflow node: Lot Scale Storage
    • Area: Residential

    • Template ID: 2

    • Inflow: roof runoff

    • Demand Priority 1: non potable demand**

    • Demand Priority 2: outdoor demand**

    • Demand Priority 3: -

    • Storage Volume (m3): 5

Results

You should have access to tiles depicting: lot scale in and outflows; water being recycled within the project area’s water supply system at a lot and sub catchment scale; and the overall water balance of the catchment. The bar graphs comprising the tiles will allow you to witness how the different scenarios compare in terms of the various elements of the urban water cycle.

Lot scale

The lot scale outputs are shown below.:numref:lot_scale_inflow shows total inflow of water for all lots and Fig. 19 shows the total outflow. Note that the rainfall has been disabled in Fig. 18. The volumes reported in the user interface are the total flow after a lot scale storage. This means, for the RWHT scenario the total inflow and outflow will be reduced. Note, that the residual volume in the storage tank at the end of the simulation might cause a slight discrepancy when comparing the total inflow to the total outflow.

The graphs show that the with installation of RWHT an estimated 43k m3 can be saved and the storm water runoff reduced by 8%, reducing the outdoor demand by 30% and non potable demand by 20%

_images/lot_scale_inflow.png

Fig. 4 Lot scale inflow

_images/lot_scale_outflow.png

Fig. 5 Lot scale out flow

_images/lot_scale_storage.png

Fig. 6 Lot scale storage

Sub catchment scale

The sub catchment results are shown below.:numref:sub_catchment_inflow shows the total inflow of water for all sub catchments and Fig. 23 shows the total outflow. Note that the rainfall has been disabled in Fig. 23. The volumes reported in the user interface are the total flow after a sub catchment scale storage. This means, if as shown in the figures a water recycling system is installed, the total inflow and outflow will be reduced. Note, that the residual volume in the storage tank at the end of the simulation might cause a slight discrepancy when comparing the total inflow to the total outflow.

The graphs show that the with implementation of a waste water recycling scheme an estimated 50k m3 can be saved, reducing sewerage by 23% and the potable demand by 13%.

The combined effect of the RWHT and waste water recycling can reduce the required imported water (potable, non potable and outdoor) by 90k m3 or in total 24%.

_images/sub_catchment_outflow.png

Fig. 7 Sub catchment inflow

_images/sub_catchment_inflow.png

Fig. 8 Sub catchment outflow