About the action data
Actions are specified at the sub-catchment scale. For each action, the Reefonomics interface allows the definition of the default water quality effectiveness and default cost as well as refinement of these values to provide sub-catchment specific values.
Computationally, the operations occur at a sub-catchment spatial scale.
Metadata
An action has a name and a description. These are free text fields. Each action also has the ability to attach associated information. This is for supporting information such as source reports or papers that describe the action or its performance.
Load reduction effectiveness
There are three alternative ways of specifying the water quality reduction effectiveness for an action:
- Efficacy: -1 to 1 value representing the (proportional load reduction)
- Yield: load per ha reduction (usually -2 to 2 and kg/ha, t/ha)
- Fixed load: total load from action (e.g. a wastewater treatment plant)
Determining the industry-level water quality effectiveness values
The industry-level efficacy and yield values for sugarcane, banana and cropping industries are derived from modelling simulations conducted by the Paddock to Reef paddock modelling team and supplied for use in the P2R Projector tool.
The sugarcane and banana simulation summary data has estimated yields for fine sediment (FS), drainage dissolved inorganic nitrogen (dissolved DIN) and runoff DIN.
The cropping industry has estimated yields for FS only. The yields are reported as long-term annual average values delivered to stream for different soil types, and up to three climatic regions for each sub-catchment. These values are reported for combinations of management practices (300+ for sugarcane, less for banana and grain).
The area of each soil type for each sub-catchment is known. The general approach to determining the long-term average annual yield, from each management practice for each sub-catchment, is to:
- Create an area weighted average yield for each combination of management practices. The area weighting is based on proportion of the soil type for the industry in the sub catchment.
- For each simulation, determine the grade of each management practice
- Average the yield for the management practice across all climate (dry, med, wet) for a sub-catchment. For example all simulations where soil management is categorized as B grade get averaged for a sub-catchment.
- The proportional difference in the sub-catchment average management practice yield is the efficacy for the grade change. For example transition from C to B action = (Cyield-Byield)/average yield.
- To determine the yield change (number of kg/ha to reduce load by) due to an action requires the delivery ratio to be applied. This is because Reefonomics reports on load change at the reef not at the sub-catchment. The average delivery ratio for the sub-catchment for the constituent is applied to get an effective delivery to reef yield for different practices. The yield values for say C to B grade change are then yield to reef C – yield to reef B.
Cost
The cost element of the action is the ‘donor initial’ cost and ‘donor ongoing’ cost. Both costs are assumed to be $/ha ($/km for linear features).
The donor ongoing cost is assumed to apply uniformly over the life of the activity. The costs can be different for each sub-catchment.
The action cost estimates have been curated by NCEconomics.
Water quality response curve
The water quality response curve represents the time to achieve full load reduction. Response curve applies to all sub-catchments. The response shapes are:
- Immediate
- Linear over 15 years
- Rapid initial response then slowing (over 15 years)
- Slow initial response then increasing (over 15 years)
The response shapes are used to demonstrate the likely temporal response of load reduction in the results.
Confidence in water quality effectiveness
The confidence score represents the robustness of the science underpinning the estimated load reduction effectiveness. The approach adopted here is to allow experimental actions to be considered in Reefonomics, however, these will have large ‘error bands’ in the predicted water quality benefits.
A survey is answered to create a 1-5 confidence score.
The confidence score is not sub-catchment specific.
Pollutant source and destination area
Each action is applied to a pollutant source. The pollutant source is used to define where the load is reduced from. The pollutant source is also used to determine the amount of available area that the action can be applied to.
The destination pollutant source allows the area that has been converted to be tracked. For example nutrient management grade C to grade B transition requires the area to be tracked so that subsequent actions working on nutrient management grade B area can apply to the now increased area.
An important note is that as well as practice management transition, industry level transitions are catered for. For example, transitioning from grazing to conservation, Sugarcane to horticulture etc can be modelled.
Adoption level and rate
The determination of the peak adoption level (%) and the time required to achieve that level of adoption (years) is achieved by completing a survey. The survey and underlying computational method employs the ADOPT method.
In order to handle adoption influences that may not be explicitly captured by the ADOPT method, such as the impact of regulation, the user can override the calculated survey results with manually entered adoption level and rate values.
The annual level of adoption for an action is calculated at the time of computation by assuming a linear response. This is a known limitation, and exploration of an appropriate adoption diffusion curve shape is yet to be explored.
Co-benefits
The co-benefits are determined via a survey of likely benefit/disbenefit across a series of five domains with sub-measures:
Environmental
- Wetlands
Economic
- Farmer
- Industry/district
Social
- Social learning
First Nations People
- First Nations People explicit involvement in actions
Climate
- Carbon sequestration potential
- Land resilience potential
- NOx change potential
The combination of the measures to a domain level value is by weighted average (default weighting is 1). The domain values are then combined by a weighted average (default weighting is 1) to give an overall co-benefit score. The presented values are a -1 to 1 range.
The domain level co-benefit scores can be manually overridden.
The determination of the action co-benefit score is by multiplying the co-benefit score by the area of action implemented divided by the overall sub-catchment area. For linear actions (gully, stream) the score is based on the proportion of the available linear area (e.g. total stream length).
