Annual Accounting - SRG

Version

Source version 3.8.12

Dependencies

 Annual Accounting can be used by any of the following node types which are referred to as "Account Hosts":

1. Water User Nodes (with attached Supply Point Node)
2. Environmental Demand Node
3. Bulk Licensing Node

Exact configuration within each of these Accounts Hosts varying but the underlying Resource Assessment system is consistent.

Assumptions

The assumptions and limitations are summarised in Table 1.

Table 1 - Assumptions and constraints applying to Annual Accounting

Annual Accounting

The Annual Accounting implementation in Source follows the same basic concepts as other types of resource assessment systems, namely:

• An available resource;
• A defined water year;
• A set of account types;
• Accounts to which water is allocated, and for which usage is tracked; and
• Possibly an owner (for example, the state "NSW"), when ownership is enabled.

The modeller is given the flexibility to determine rules such as:

• Dates of the water year.
• The frequency of the resource assessment and allocation process. By default this occurs annually at the start of the water year.
• How the available resource is determined. The main feature of this type of system is that the flexibility of functions is provided within a structure that is common to Annual Accounting methodologies in different jurisdictions.
• Rules of allocation.
• Usage limits (in addition to the account balance)
• Carryover type (spillable or non spillable)

Event Triggers are provided to allow modelling of carryover and other less commonly used methods in Annual Accounting.

There are some features that differentiate Annual Accounting from other types of resource assessment system. In Annual Accounting, a forward projection of usable future inflow to the end of the water year may be included in the available resource and subsequently influence the allocation announcement. Allocations may be reviewed and adjusted throughout the water year, typically as events occur. This type of review looks at the ability of the system to supply the demand for the rest of the water year. There may be some point within the water year when no further allocation announcements are made, typically at the end of the growing season.

To model Annual Accounting, Source performs resource assessment at a user-specified frequency (via the Reassessment Trigger), adjusting the available resource for demands supplied to date. It provides the modeller with a simple mechanism to define the relationship between the resource and allocation - this is Available Resource versus Allocation (ARA) table. At each reassessment this relationship is used to determine the volume of water allocated to each account type represented, based on that time-step’s available resource estimate (See the section on Account Types and the ARA Table). Functions can also be used instead of the ARA table to determine an Account Type’s allocation. In cases where the Account Type has an increase in allocation from the previous resource assessment, the change in allocation (increment) is assigned to its accounts.

Available Resource

The available resource for an Annual Accounting system is calculated as shown in Equation 1.

Figure 1. Example Resource Calculations for the Goulburn one year planning period and Source configuration comparison

Active Storage

One or more storage nodes may be selected as sources of water for the Annual Accounting system. Each of the selected storages contribute their "Active Storage".

In its simplest form, the Active Storage is a measure of the current volume in the storage minus the dead storage volume. 

When ownership is enabled and the Annual Accounting system is linked to an owner, the volume only includes the selected owner’s share of the water in the storage.  Meaning that the total volume of Active Storage is scaled by the ownership percentage.

Active Storage can also be affected by the configuration of each of the Storage's "Evaporation To End of Season" and "Minimum Inflow To End Of Season" settings.  For each Storage the user can specify a monthly pattern dictating the Minimum Inflow as well as the Evaporation.  They can also further control how these patterns are used depending if they want to use the inflow for resource and inflow for evaporation.

Active Storages are summed together and added to the Available Resource during reassessment.

Tributary Inflow

This part of the Available Resource equation represents the Annual Accounting system’s recession tributary inflow volume. One or more Inflow nodes may be used to represent tributary inflows providing water to the system. A recession factor is required for each - the function to calculate this is entered via the Annual Accounting system’s user interface. The function should return a percentage/proportion of the inflow node's outflow volume (on the assessment day) which will be considered the contributing volume available for the remainder of the planning season.  The value should, but doesn't need to, relate to the number of days left in the season.  The value is likely to be very much greater than one (100%) until the last few days of the planning season.

When ownership is enabled and the Annual Accounting system is linked to an owner and the tributary inflow values used only consist of the selected owner’s share of the total.  The volume added to the available resource by each Inflow node in a reassessment is shown in Equation 4.

Equation 4 - Tribuary Inflow
Where "OutflowVolume" represents the Inflow node’s Outflow Volume.

Tributary Inflows are summed together and added to the Available Resource during reassessment.

Commitments are specified via functions and the modeller may specify an arbitrary number of them. They can be used to represent (or reserve water for):

• Carryover - An example is the environment’s carry-over volume from the previous water year in the Wimmera / Glenelg system in Victoria. This is the remaining volume after allowing for the environment’s share of storage losses and spills in current allocation year.
• Forecast Losses for Remainder of Water Year - There may be several different losses that could all be added into the resource assessment calculation separately. These could include river losses, channel losses and evaporation losses.
• Fixed Adjustments - Examples include environmental flows, compensation flows and water quality dilution flows. In the Wimmera / Glenelg system, there is an adjustment for amount of borrowed water returned to the Minister of Environment under sub-clause 6.1(c) of the Flora and Fauna Bulk Entitlement Order.
• Reserve - An example in the Wimmera / Glenelg system is the amount of water to be retained in head-works reservoirs this water year to provide for a basic supply next water year.

Some of the above examples could also be represented by Account Types. The volume of water reserved for purposes such as water quality might be independent of allocation, while that required for reservoir evaporation and transmission losses might vary with allocation. The water uses defined under Commitments should generally be those that are independent of allocations within the Annual Accounting system, and for which no water user accounts are required within the system. An example could be water in the system’s storages that is to be managed by another resource assessment system.

Commitments are summed together and the total subtracted from the Available Resource during reassessment.

Other Resources

Other Resources are specified via functions and the modeller may specify an arbitrary number of them.  They can be used to add to the available resource a wide range of water resource types and facilitate representation of the following inflow volumes commonly used in Annual Accounting:

• Minimum historic usable cumulative tributary inflow volume.
• Minimum historic cumulative headwater inflow volume

These volumes are based on historic (rather than modelled) data for each month, and are forecasts of the total minimum inflow volume from the current month to the end of the water year or season.

Other applications include inter-basin transfers and groundwater resources. These resources may be managed by another resource assessment system. An example of an inter-basin transfer is the Wimmera / Glenelg system where water is taken into the Wimmera-Mallee system from the Goulburn-Broken system via the Waranga Western Channel, and water availability is managed via the Goulburn-Broken resource assessment system.  Source allows functions to be entered to allow for this linkage between systems, as well as to provide access to relevant model variables.

Other Resource are summed together and the total added to the Available Resource during reassessment.

Usage to date

This parameter represents how much of the water allocated has been ordered or used by Account Hosts in the water year to date. Usage for individual accounts is tracked by Source and may be accounted when water is ordered, delivered, or diverted. The timing of usage accounting depends on whether water order debiting or water usage debiting applies (associated with the resource assessment system).

When the modeller selects the "Usage from Account Host" option, the total of usage in all accounts that has been tracked by Source is used, as in, it uses the value taken from orders made by Account Hosts. Alternatively, the modeller may input an function to determine the usage value (the "Usage from function" option). An example application would be to adjust the tracked value to represent a conveyance loss.

Usage to Date is added to the Available Resource during reassessment.

Spill to date

Spill to date represents water spilled from accounts in the current water year up to date.  Spill reduction for each account is tracked in Source, this is the total spill reduction from all accounts within this accounting system from start of water year to date.

Total Spill to Date is added to the Available Resource during reassessment

Adjustment

Adjustments represent changes to the accounts that have occurred via Triggers (not just the "Adjustment" Trigger)  Triggers allow changes to Account to occur based on specified Conditions and may result in adjustments to many account properties.  When these changes to occur they are tracked to ensure that the modifications are factored into allocation.

Adjustments are subtracted from the Available Resource during reassessment.

Account Types

As with other types of resource assessment system in Source, Account Types in an Annual Accounting system represent a type of water to be allocated or assigned. Some examples are:

• Types of entitlement or licence, sometimes referred to as "Products". Examples include High Reliability Water Share (HRWS) and Low Reliability Water Share (LRWS) in Victoria, and High Security and General Security in NSW;
• Basic rights, such as stock and domestic rights, and native title;
• Environmental allocation;
• Reserve. For example, in the Murray, Goulburn, Lachlan and Murrumbidgee systems, water is set aside for following seasons. In the Thomson/Macalister system, allocations are made to a Drought Reserve, which has much the same purpose;
• Transmission and operational losses (TOL) in the Lachlan system;
• Spill entitlement. An example of where this occurs is the Thomson / Macalister system in Victoria where, if Lake Glenmaggie spills, Southern Rural Water can declare a period that spill entitlement is available and the water delivered to irrigators during this period is not counted as part of their seasonal allocation;
• Carryover account types, such as the Spillable Water Accounts (SWAs) in Victoria. Carryover is widely available in annual accounting systems. It allows individuals to carry over part of their unused water allocation (up to a prescribed limit) for use in the following season. It was introduced to annual accounting in northern Victoria in 2006/07 as an emergency drought measure- see DSE (2009), with a limit of 100 per cent of entitlement (ie an individual’s carryover plus allocations cannot exceed 100 per cent). SWAs were introduced on 30 June 2010 to reduce the risk of entitlement-holders losing their carryover in full allocation years. As allocations increase throughout the following season, these are added to users’ accounts until carryover plus allocation equals 100 per cent of the entitlement volume. After this, any additional allocations are credited to the SWA. Throughout the season, the storage manager assesses the risk of the storage spilling during the remainder of the season. Only when the storage manager declares the status of system as "spilling", can the entitlement holders access the water in the SWA;
• Bulk entitlements (BEs) in Victoria, and Conveyance licences used in the Murrumbidgee and the Murray in NSW. In Victoria, BEs are issued to Water Authorities to define their respective rights to water (NRE, 1995). The NSW Conveyance licenses are assigned to irrigation companies, which then allocate water to individual irrigators;
• Nested or linked resource assessment systems (known in Victoria as allocation groups). One example is the Goulburn system link to the Loddon system. Allocation for the Loddon HRWS account type is calculated firstly based on available resource in the Loddon system and then compared with the Goulburn allocation. The lesser of the two is the final Loddon allocation; and
• Off-quota water, or Off-allocation systems (a type of nested resource assessment system).

Some of the above examples could also be represented using the Annual Accounting system’s Commitments or Other Resources functions.  An Account Type should be used if its allocation is dependent on allocations to other Account Types within the Annual Accounting system, or usage of the allocation needs to be tracked.

The sub-sections below describe the use of Account Type parameters or relationships in relation to Annual Accounting systems.

Priority

The modeller may enter a Priority value for an Account Type to indicate the differences in priority between licence types - for example High or General Security access. In Annual Accounting, Source does not automatically differentiate allocation according to priority, in the interest of flexibility, the modeller may reference Priority in functions that calculate allocation, or simply use this parameter to improve clarity. The ARA Table may also be used to prioritise allocation between Account Types.

Figure 2 and Figure 3 are examples where the ARA table is used to give high security Account Types a higher priority of allocation than general security account types.

Figure 2 - Example account type v total available resource relationships

Figure 3 - Example account type v total available resource relationships

Unit Shares / Entitlement

The Unit Shares / Entitlement parameter is only used when allocation is assigned in percentage increments using the "Percent (with linked volume)" option described under the sub-section Method to apply for this Account Type in the ARA table, and can only be entered when the modeller does not tick the "Use Unit shares / Entitlement from accounts?" parameter. It represents the volume to assign to the Account Type at 100% allocation. The Unit Shares / Entitlement parameter is designed for use in Account Types without associated accounts - for example, a transmission and operational loss account type. It can however also be used when Accounts are linked to the Account Type.

Allocation Calculation

This parameter determines the mechanism by which the allocation to an Account Type will be made.

The default option is the "Available Resource Allocation Table" entry. When this is chosen, a piecewise relationship must be specified for the Account Type that matches the Account Type’s allocation to a volume of available resource. Example uses of this option are for the Victorian HRWS and LRWS volumetric entitlements.

The other option is "Function", allows the modeller to specify the function by which allocation is calculated. This function may reference a wide range of variables available in the model, including allocations to other account types and resource assessment systems. Example applications of the "Function" option would be for spill entitlement, reserve, carryover, off-quota and nested or linked resource assessment system Account Types.

A function could be used to implement an adjustment to allocations to comply with the Murray Darling Basin cap, such as in the Goulburn-Broken system. In this instance, a relationship of the rolling average "cap" diversions minus modelled diversions versus allocation reduction percentage is applied to reduce LRWS allocations. The function would incorporate:

• A time series of rolling average cap diversions;
• Comparison of modelled Usage to date and the time series, to determine the difference;
• Use of the look-up table determine the reduction amount; and
• Application of the reduction to the percentage allocation.

Available Resource verses Allocation (ARA) Table

The ARA table described in the previous sub-section contains a relationship for all Account Types with the relevant Allocation Calculation Method.

Use of the ARA table for multiple Account Types allows the modeller to define the interdependencies between them.  One example is the transmission and operating loss account (TOL) for the Lachlan system.  At each level of available resource, a volume is reserved for TOL, which cannot be allocated to high and general security account types. An ARA table with TOL and other Lachlan system account types is shown in Figure 4.

Figure 4. Available resource versus allocation table (example only)

Another example is the relationship between HRWS and LRWS account types in Victorian river systems to implement a reserve policy. In this case, the allocation is done according to projections over one year and two year planning periods, as shown in Figure 4.

 It can be seen from table that as the resource available increases, allocations increase up to 100% of HRWS entitlements based on the ARA relationship for the one year planning period. There will be no increase in allocation after 100% until enough resource is available to supply 100% of HRWS entitlements in the following season. Then allocations greater than 100% or LRWS allocations can be announced with further improvements in the available resources, using the ARA relationship for the two year planning period. The ARA tables to implement this type of relationship between Account Types in two such Annual Accounting systems (1 year planning, 2 year planning) are shown.

Method to apply for this Account Type in the ARA Table

• Percent (with linked volume) - This is designed for cases where allocations are announced as a percentage of the annual volumetric entitlements. This is generally the case in NSW and Victorian systems. The "linked volume" is the total volume of shares for the Account Type - which represents the volume allocated to the Account Type at 100% allocation (see the sub-section on the Shares parameter for more detail). For each ARA Table row, the modeller specifies a percentage which is multiplied by the share volume and included in the (read-only) available resource column total.
• Percent (with Function) - Allocations can be announced as a percentage of annual volumetric entitlement.  This gives the modeller more flexibility to define percentage by function in ARA Table rows.
• Volumetric - used when allocations are announced as a volume. This is the case in the Wimmera / Glenelg system and in the Lachlan for basic rights (native title rights, domestic and stock rights).
• Monthly Varying - Volumetric allocations to some Account Types will change over the year. An example is the TOL account type in the Lachlan system. The TOL volume may change each month due to the fact that losses such as evaporation varies according to climatic and other conditions. The modeller can also specify whether the month’s TOL volume should be used for the whole month, or whether it is necessary to interpolate between current and next month values to determine TOL for a particular day.
• Function - Allocations are announced through a user-defined function which is fixed and not based upon the Available Resource.   Only a single function can be assigned.
  
  

• Percent with linked volume - The modeller enters a number of shares for the account type. In each row of the ARA table, the modeller inputs the account type’s allocation percentage. Source calculates the account type’s corresponding allocation volume for the row as:

If Use Shares From Accounts is "Yes", the account type’s share volume is derived from its accounts:

If Use Shares From Accounts is "No", the modeller has entered the account type’s share volume:

• Volumetric - The modeller enters the account type’s allocation for each table row - ARAAllocation(type,r).
• Monthly varying - The modeller enters a monthly time series of allocation volume for each table row - ARAAllocation(type,r,m).

The value shown in the Resource column of the ARA table is the sum of allocation volumes for each of the account types - ARAAllocation(type,r).

Announced Increment and Maximum Announced Percent

Allocation increments are calculated each time there is a reassessment and distributed to accounts. This is to model the "Announced Allocations" made over a season or water year. For example, in the northern Victorian systems (Goulburn and Murray), allocations are announced fortnightly during droughts and monthly in normal and wet years.

When Method to Apply for this account type in the ARA table is "Percent (with linked volume)", the increment is calculated as a percentage. Percentage announced allocations are often made in increments, hence Source rounds the percentage allocated to the nearest value of Announced Increment. To allow for situations where there is a maximum percent allocation allowed, Source allows the modeller to configure a parameter to limit the allocation percentage.

Carryover

Carryover behaviour is configured on an Account Type bases and affects all the Accounts of this type.  This affects the carryover balance and how it is used by the system.

Carryover relies on triggers to move allocation from the Account Balance to the Carryover Balance. It is possible to specify a wide range of events that cause the carryover trigger to execute, however, this is normally done at the end of the Water Year in the Post phase just before Account truncate / write-off.  When a carryover trigger is used, the amount to carry over (add to the account type’s entitlement) is calculated as shown in Equation 5.

Equation 5
where: CarryoverMax(type) is the maximum carryover limit for the Account Type a is an Account of Account Type Balance(a) is the balance of Account Carryover%(type) is the specified carryover percentage for the account type type is the Account Type

Maximum effective allocation - a limit to total water availability. If there is a limit, user specifies the maximum proportion of entitlement allocated + carried over  to account permitted at any time in the water year. This is to limit volume allocated so as not to exceed a maximum limit and also to ensure that any water that can not be allocated to an individual account will be reallocated to other users.

Carryover Type - user can define whether carryover is spillable or not. If "Non Spillable" is selected, then there is no (zero) spillale water. If "Spillable", source provides two methods for calculating spillable water which is controlled by the Spillable Volume Calculation Method.  These are: 

1. Carryover - Use, spillable water is equal to carryover - total usage from carryover - total spill reduction from carry over, which means all the remaining carryover (after any usage or deduction) is spillable.  This is taken into account so resolves to be simply the current Carryover
2. Total water - 100% is for Victoria case.  It sums the allocation for each account which have already occurred this Water Year and adds the scaled Carryover entitlement over the whole year.   The overall Account entitlement is deducted as is the total SpillReduction so far this Water Year.  If the parent Account Type is configured for Water being Available While Spillable then the amount is deducted by the Carryover usage so far this water Year,

Equation 3.1 - Carryover - Use

Spillable Trigger - If carryover is spillable, the user can enter a function to determine if water remains spillable in the current time-step. This will generally be a boolean function of time of year or storage(s) levels. The format of boolean function is "IF A>B,1,0", "1" indicates the action will occur and "0" means action will not happen.  

Water Available While Spillable - controls whether water is available while spillable.  For most spillable water account, spillable water is not available to the user, however, Victoria Inter-Valley Transfer accounts are useable while spillable. 

Basis of Spilling - determines how to calculate spill reduction shared among users, three options are available:

1. Emptied on spill or pre-release is to totally empty spillable water account if a spill or pre-release occurs.
   
2. Reduce Pro-rata is to spill based on proportion (account spillable water / total spillable water) of spill source volume.  
   
3. Equalise spillable carryover proportions is a rule special for Barmah-Millewa Forest spill. The way this spilling rule works is:
   • Spill first from the account with the greatest carryover as a percent of its entitlement.
   • When the percentage carryover of the first account reaches the percentage of the second account, spill from the first and second pro-rata until the third highest account is reached,
   • Continue on as above until all carryover is spilled or all spill is assigned.

Spill Reduction Priority - to specify priority of spill, the lower the number the higher the priority, for example, an Account Type with "1" priority will spill prior to an Account Type with "2" priority.  If different Account Types are emptied on spill and have different priorities, the second priority Account Type does not empty until volume of physical spill after empty on spill triggered exceed the amount written off the first priority carryover account. But if different physical spill sources are used this does not apply. If different Account Types use the same spill source and have the same spill priority, the order to spill for different basis is Emptied on spill first, followed by Equalise Spillable Carryover Proportions and Reduce Pro-rata has the lowest priority.

Use Account Type Spill Volume - to specify a separate spill volume source for each Account Type. If specified, the volume specified for an Account Type would be used in preference to the allocation system spill source (configured at the System level). This is to cope with Barmah-Millewa water which receives allocation from both the Victorian and NSW allocation systems.

Accounts represent an Account Host's entitlement to a type of water. Hence, they are linked to an Account Type and have a number of shares in that Account Type’s allocation. A water user may have more than one account in an Annual Accounting system. For example, Victorian water users may hold both a HRWS and LWRS accounts. In the Thomson / Macalister system, water users may also have a spill entitlement and off-quota account.

Previous usage, usage tracking and usage limits

The modeller can configure the account’s Previous Usage for the water year. Source keeps track of usage over the water year so that it can be taken into account when calculating the available resource (see the Usage to Date sub-section) and allocation (see the Allocation Calculation Method sub-section under Account Type). Account level usage caps may also apply in Annual Accounting systems - this can be implemented by adding a usage limit to the Account.

Unit shares/Entitlement

Although this parameter is expressed as a volume, it usually represents a number of unit shares assigned the account. Parameters for the associated account type determine when Number of Shares represents a volume at 100% allocation:

• The Account Type is not in the ARA Table (Allocation Calculation Method is "Function"); or
• The Account Type is in the ARA Table, and:
  • Method to Apply for this account type in the ARA table is "Percent (with linked volume)"
  • Use Unit Shares/Entitlement From Accounts? is "Yes"

Most general security access licences are expressed as a relative unit share of the available water rather than as an annual volume (CSIRO, 2008a).

For calculations relevant to Number of shares / Entitlement, see the sub-section on Allocate to Account Types and Accounts within each Account Type in Model Phase: Resource Assessment and Water Accounting.

Initial Account Balance and Account Balance

This parameter is the starting Account Balance.  Account Balance is used in Source to limit to the volume of water a water user may order and/or access using the account.  During resource assessment, the Account Balance is credited with the account’s share of the allocation to the Account Type.

Initial Allocation

 Allows the user to set what proportion of the Entitlement that is initially allocated.

initial Carryover Scalar

Carryover Scalar initial setting.  This controls how much of the Carryover Start of Water Year is assigned to the Carryover Balance so far this Water Year,

Carryover Start of Water Year

This represents the total amount of potential Carryover that can be assigned to the Account based on the Carryover Triggers from the previous Water Year.  This is scaled by the Carryover Scalar which controls how much of this total Carryover volume that has been assigned to the Carryover Balance.

Previous Spill from Carryover

Sets-up the previous spill that has been already accounted for in the current Water Year,.

Model phase: Initialisation

Variables are initialised as follows:

• The previous allocation to each Account Type (AllocPrevious%(type), AllocationPrevious(type)) is zero for the first time-step;
• If the modeller has specified account limitations based on a unit share then the total volumetric limitations for each account are determined; and
• Account usage is initialised by evaluating the previous usage settings specified by the modeller and the total accumulated for the RAS.

Model Phase: Time-step Beginning, Time-step End

At the start or end of a time-step, Annual Accounting triggers may be executed, depending on configuration.  If the trigger condition returns a true value, the trigger action is executed. By default Annual Accounting systems have a start of water year trigger for reassessment.

Actions at the start of a water year

At the start of each water year the running usage totals etc. are reset to zero.

Model Phase: Resource Assessment and Water Accounting

Figure 5b provides an overview of the Annual Accounting resource assessment method. More detail on the steps involved follows.

Calculate Allocation for each Account Type

Model Phases: Time-step - Order and Flow Distribution

The working of these phases is described in detail in the SRG sections on Continuous Sharing - SRG, Continuous Accounting - SRG and the Water user node SRG.

In summary, at Account Hosts with the "Account Sharing" option selected, every order placed uses an Account. The volume ordered using the Account is limited to the Account Balance.  Accounts are debited either for orders placed (if the account is of an order-debit account type), or usage (where the account is of a use-debit Account Type). Water-order accounts are debited in the order phase and the total is re-credited for shortfalls in the flow distribution phase. Account Host Accounts are debited for "usage" in the flow distribution phase.

The Account Hosts perform some complex processing to determine the "usage" to assign to accounts. A running total of usage for the water year for each account is tracked by Source. This total may be referenced by Annual Accounting triggers that cap usage.

The variables used by the model are summarised in Table 2.

Table 2 - Variables Used in Annual Accounting

Input data

Input data is summarised in the following tables:

• Configuration parameters - Table 3;
• Allocation parameters - Table 4;
• Trigger parameters - Table 5. The parameters listed in this table are a sub-set of those described in Table 8;
• Account Type parameters - Table 6;
• Account parameters - Table 7;
• Per-trigger parameters - Table 8. There is one set of the parameters in this table for each trigger in the Annual Accounting System.

Table 3. Configuration parameters

A default "Start of Water Year" trigger is created with each new annual accounting system:

• Parent: The annual accounting system’s name
• Type: "Start of Water Year"
• Action type: "Re-assessment"
• Execution: "Timestep beginning"
• Time-steps from last assessment: "1"

Table 6. Account type parameters

Table 7. Account parameters

Table 8. Pre-trigger parameters

When modelling an existing continuous accounting system, the values of parameters adopted will be dictated by rules governing the operation of the system in place. When modelling new systems or modifications to existing systems, it will be a matter of professional judgement and consultation with stakeholders as to reasonable values to explore, combined with "trial and error" solutions, to arrive at acceptable parameter values.

Output data

Output data is summarised in the following tables:

• Account Type recorded output variables - Table 10;
• Account recorded output variables - Table 11; and
• Recorded output variables - Table 12

Results are provided for each time-step, although they are only calculated in resource assessment time-steps.

Table 10. Account type recorded output variables

Table 12. Recorded output variables

Reference list

CSIRO (2008a) Water Availability in the Lachlan. A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project.

CSIRO (2008b) Water Availability in the Murrumbidgee. A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project.

DSE (2009) A Proposal for Future Carryover Arrangements. Northern Region Sustainable Water Strategy

James, B., Erlanger, P. D. and Hansen, W. R. (1993) Modelling a Complex Irrigation Restriction Policy Using a General Simulation Package. Hydrology and Water Resources Symposium, Newcastle, June 30 - July 2.

NRE (1995) The Bulk Entitlement Conversion Process. Bulk Entitlements Report Series No. 2, Department of Natural Resources and Environment, Victoria.