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Understand and predict the impacts of water trade and associated changing patterns of usage on conveyance losses and delivery risks.
Continuous improvement of water user’s behavioural assumptions and
Strengthen the capability to forecast and incorporate trends in crop mixes and climate-change scenarios.
Trade Trade Manager concept
The total available water balance calculated in the Resource Assessment is passed to the water users, and the expected use is calculated based on the antecedent use (sum of previous 10 days use) or by user-defined values (for example, time series, constant value or functions). Subsequently, total tradeable water is calculated for each water user, group and system based on available water and the value of water.. The tradeable water represents the portion of the total available water balance permitted for trade based on the regulation of the relevant jurisdiction or the defined limitations.
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In Figure 2, there are three groups added to the Trade Manager named TG1, TG2 and TG3. When a particular group is selected (TG1 in this case), the following screen is displayed as in Figure 3.
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Water users belonging to each trade group can be selected from the drop-down menu of ‘Available Unassigned Water users’ and assigned using ‘Assign Water User’. Each water user can only be assigned to one group.
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Once the water users are assigned to a particular trade group, there are options to indicate whether a water user is trading or not, expected water use method, expected use expression method and value of water. The option ‘Is Trading’ is used to indicate whether a water user is participating in trade or not. This can be indicated using ‘Value’, ‘Data Source’ or ‘Function Editor’ as shown in Figure 5. Permissible values are 0 and 1. A value of ‘0’ indicates not trading and ‘1’ indicates trading. Similarly, time series values using ‘Data Sources’ and functions using ‘Function Editor’ can be used to denote whether a water user is trading or not.
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The ‘Expected Use Method’ is used to indicate the method by which the expected use (forecast) of water for each water user is calculated. There are two ways by which the expected use can be determined, either by ‘Antecedent Values’ or ‘Expression Value’ as in Figure 6.
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If ‘Antecedent Values’ method is selected, a buffer is maintained to keep a volume in a water users account equal to the last 10 days of water use. If ‘Expression Value’ is selected, the ‘Expected Use Expression’ field can be edited and the user can input the expected water use by means of ‘Value’, ‘Data Source’ or ‘Function Editor’ just like importing climate data using ‘Data Sources’.
The ‘Value Of Water’ indicates the importance given to a particular water user when involved in trade. In an economic term it would be equivalent to the price a water user would be willing to pay. As the Trade Manager is not designed to capture all economic conditions “value of water is used.’ The value of water is sorted in descending order, where a ‘Value of Water’ of 2 will be ranked higher than a ‘Value of Water’ of 1. When there is no surplus water, water will be traded from the lower value to the higher value. The user can define the value of water through a fixed value, a data source or a function. Value of water is required to be greater than 0 and the default value is 1.
If a water user is to be removed from the list of water users in the trade group, simply select the row that contains the water user and press delete. This will remove the water user from the list.
Trade Rules
The rules pertaining to trade between groups are set by ‘Trade Rules’ in the TM. Using ‘Trade Rules’, a user can define whether a trade group can trade, and set the maximum trade into and out of each trade group. Users can define Trade Rules through a fixed value, a data source, or a function. The maximum trade in and out is the total trade allowed for a particular trade group throughout a water year and is adjusted daily and reset at the start of each water year.
It has to be noted that the maximum trade in and out are set to 1000 gigalitre (GL) by default if it is defined using a fixed value. An example of configured Trade Rules in the TM window is shown in the figure below.
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In the figure above, the maximum trade that could be allowed in (Max Trade In) and out of a group is defined using a function.
Trade Manager and Resource Assessment
Previously, the implementation of Trade Plugin used by MDBA was reliant on the options available in the Resource Assessment System Trigger specification. The implementation of TM functionality in core Source has eliminated the need for trigger specifications in the Resource Assessment (RA). However, the user may need to configure the RA for adding available water for each water user as in Figure 8.
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Recorders
As TM is a new functionality in core Source, there are new recorders associated with it and they are shown in the figure below (Figure 9). The main recorder ‘Trade Manager’ is visible under the ‘Miscellaneous’ option.
The recorders and their descriptions are given below.
Trade Manager
Group Trade Value – The ‘Equilibrium Value’ at which water trade occurs in the group trading process. It indicates the threshold below which trading stops due to the unavailability of additional water for trade.
Group Trade Volume – Absolute value of total water traded in or out between groups
Group Trade Volume Water Year To Date -Cumulative group trade volume to date in a water year
System Trade Volume – Absolute value of total water traded between and within groups
System Trade Volume Water Year To Date - Cumulative system trade volume to date in a water year
Trade Groups
Net Trade – Sum of water volume traded into/out of a trading group. A positive value indicates water traded in, and a negative value indicates water traded out.
Net Trade Water Year To Date – Cumulative net trade volume to date in a water year
Water Traded In –Water volume traded into a group
Water Traded Out – Water volume traded out from a group
Water Users
Net Trade –Sum of water volume traded into/out of a water user. Positive is ‘trade in’ and negative is ‘trade out’
Net Trade Water Year To Date - Cumulative net trade volume to date in a water year
Resource Assessment
In addition to the recorders in the TM, there are two additional TM related recorders under Resources Assessment, and they are:
Net Trade – Sum of water volume traded into/out of an account host, account type or accounts
Net Trade Water Year to Date – Cumulative net trade volume of an account host, account type or accounts to date in a water year
These recorders are available under ‘Account Hosts’, ‘Account Types’ and ‘Accounts’ in the Resource Assessment.
It is to be noted that the ‘Account Adjustment’ recorder in Resource Assessment does not include trade. The trade volume values are included in the available resources calculation in the Resource Assessment.
Example Model using TM
To illustrate the use of TM, a simple example model is shown and described briefly below.
Model configuration
In the example model, as in Figure 10, there are nine water users each with a demand of 1 ML/d.
The Trade Manager (TM) in the model is configured as below. There are three trade groups participating in the trade and they are TG1, TG2, and TG3. Each trade group is assigned three water users; for example, TG1 is assigned Z1P1, Z1P2, and Z1P3, TG2 is assigned Z2P1, Z2P2, and Z2P3, and TG3 is assigned Z3P1, Z3P2, and Z3P3.
As indicated in Figure 11, all the water users of TG1 and other trade groups are participating in the trade (Is Trading = 1). ‘Expression Value’ is selected as the expected use method. The ‘Expected Use Expression’ is defined by functions for all the water users in this case. The ‘Value Of Water’ is also defined using functions. The ‘Value Of Water’ does not have a unit, as it is used to indicate the importance or rank of that water user when involved in trading.
The Trade Rules are defined for each group in TM, as in Table 1.
Trade Group | Can Trade? | Max Trade In (ML) | Max Trade Out (ML) |
TG1 | 1 (Yes) | 10 | 10 |
TG2 | 1 | 10 | 10 |
TG3 | 1 | 10 | 10 |