Identify useful variables and assemble metadata

Subtask Description:
Describing the model at process and functional levels.

Action points of the implementation:

The previous stage (System Design) resulted in a preliminary conceptual model of the “virtual system” comprising from the cause-&-effect chain and the related ecosystem and socio-economic components. Review this model, revise if necessary, and identify the processes and state variables that will be simulated and the functional units that will be used to group them. Distinguish the parts of the conceptual model that will be included in the simulation models from those which will be the subject of other analyses.
Prepare a draft table of key processes for each functional unit in the simulation model.
Identify the state variables in each functional unit.
Write equations for the model state variables and processes, noting the sources for these equations.
Check the equations for correct dimensions and units in each term and for conservation of mass or energy where appropriate.
Identify the parameters for which values will be needed, and either find sources for these or note that they will be estimated by fitting simulations to observations.

Result: A description of the model in diagrams and tables.

Area:
Himmerfjärden , Sweden

Policy Issue:
Eutrophication status and reduction.

Human Activities:
Urban sewage discharge, agriculture and industrial activity, tourism.

General Information:
Nutrient loading has caused increased turbidity, loss of biodiversity (including submerged aquatic vegetation), deep water oxygen deficiency, phytoplankton blooms and biodiversity loss. The main stakeholder concerns are connected with tourism, recreational activities and nature enjoyment, and the sustainable implementation of the WFD that poses economic challenges for several activities in the area.

Example of Implementation:

Process Name	Scenario for reducing nitrogen loadings
Function in model	Choose one or several policy options for reducing nitrogen loadings

Variables IN	Policy option/s chosen from the data bases, HSTP, AGR, and/or PS.

Information IN	Measures for reducing nitrogen loadings

Variables OUT	Nitrogen loadings and nitrogen reduction (kg)

Formulation	The nitrogen reduction is dependent on the scenario chosen.

Reference	Policy options as agreed upon with the SSA Reference Group of stakeholders

Process Name	TEMPORARY MARINE MODEL: Secchi depth
Function in model	ESE link, ecology links to socio-economic systems

Variables IN	Yearly nitrogen discharges (kg) and nitrogen reductions (kg), DB_N loadings HSTP/AGR/PS and DB_N reduction HSTP/AGR/PS

Information IN	Variables IN dependent on scenario

Variables OUT	Secchi depth improvement (in metres)

Formulation	Secchi depth (metres, summer) = (-0.0035*(nitrogen discharges tonnes/year)+4.2)-2.74

Reference	The estimation used is slightly adjusted but initially estimated by Jakob Walve.

Process Name	TEMPORARY MARINE MODEL: Secchi depth
Function in model	ESE link, ecology links to socio-economic systems

Variables IN	Yearly nitrogen discharges (kg) and nitrogen reductions (kg), DB_N loadings HSTP/AGR/PS and DB_N reduction HSTP/AGR/PS

Information IN	Variables IN dependent on scenario

Variables OUT	Secchi depth improvement (in metres)

Formulation	Secchi depth (metres, summer) = (-0.0035*(nitrogen discharges tonnes/year)+4.2)-2.74

Reference	The estimation used is slightly adjusted but initially estimated by Jakob Walve.

Process Name	TEMPORARY MARINE MODEL: Secchi depth
Function in model	ESE link, ecology links to socio-economic systems

Variables IN	Yearly nitrogen discharges (kg) and nitrogen reductions (kg), DB_N loadings HSTP/AGR/PS and DB_N reduction HSTP/AGR/PS

Information IN	Variables IN dependent on scenario

Variables OUT	Secchi depth improvement (in metres)

Formulation	Secchi depth (metres, summer) = (-0.0035*(nitrogen discharges tonnes/year)+4.2)-2.74

Reference	The estimation used is slightly adjusted but initially estimated by Jakob Walve.

Process Name	TEMPORARY MARINE MODEL: Secchi depth
Function in model	ESE link, ecology links to socio-economic systems

Variables IN	Yearly nitrogen discharges (kg) and nitrogen reductions (kg), DB_N loadings HSTP/AGR/PS and DB_N reduction HSTP/AGR/PS

Information IN	Variables IN dependent on scenario

Variables OUT	Secchi depth improvement (in metres)

Formulation	Secchi depth (metres, summer) = (-0.0035*(nitrogen discharges tonnes/year)+4.2)-2.74

Reference	The estimation used is slightly adjusted but initially estimated by Jakob Walve.

Process Name	TEMPORARY MARINE MODEL: Secchi depth
Function in model	ESE link, ecology links to socio-economic systems

Variables IN	Yearly nitrogen discharges (kg) and nitrogen reductions (kg), DB_N loadings HSTP/AGR/PS and DB_N reduction HSTP/AGR/PS

Information IN	Variables IN dependent on scenario

Variables OUT	Secchi depth improvement (in metres)

Formulation	Secchi depth (metres, summer) = (-0.0035*(nitrogen discharges tonnes/year)+4.2)-2.74

Reference	The estimation used is slightly adjusted but initially estimated by Jakob Walve.

Comments:
This subtask can help to keep track of the formulation of the model and document it more efficiently, as it provides transparency to each formulated process and gives adequate information to the external reader about the use of the process, the inputs and outputs and, most importantly, the references, when available. The example provided here uses scenarios of nitrogen reduction instead of main processes.

Contact: Frida Franzén frida@enveco.se , Gerda Kinell gerda@enveco.se .