Identify useful variables and assemble metadata

Subtask Description:
Input approximations and transformations.

Action points of the implementation:

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 WFD that poses economic challenges for several activities in the area.

Example of Implementation:

Ecological inputs
Vertical differentiation : For the water exchange, the system is approximated as a two-layer system, with constant surface and bottom volumes. Salinity CTD profiles were used to determine the approximate depth of the pycnocline.

Water runoff: The water runoff from land was available as monthly averages for the whole land area. The runoff was divided according to the areas of the sub-drainage basins of the respective model basins, assuming the same area-specific runoff.

Nutrient inputs from rivers: The nutrient data from Moraån, which drains into Näslandsfjärden, was used to estimate nutrient inputs to the model basins Näslandsfjärden (which includes also Stavbofjärden) and Hallsfjärden. Data from Fitunaån was used to estimate nutrient inputs from land to Himmerfjärden. The places for measurements in rivers are shown in the following figure (green points).

Nutrient inputs with rain : Nitrogen input with rain was estimated from measurements of rainfall and nitrogen concentrations in rain available from national monitoring at Aspvreten and Tyresta, in the vicinity of Himmerfjärden.

Light: Light data were from Stockholm.

Calibration data : For calibration, the salinity and nutrient data from different depths were average for each box, but excluding the deepest measurements, which represent very small volumes. This approach will later be replaced by volume-weighting of the calibration data.

Economic and social inputs
The input values used in current version only concern the Himmerfjärden proper drainage basin and the catchment areas of this basin. Similar models of the other two sub-drainage basins will be developed including unique input values for those areas. The economic and social inputs in the model are in the Formulation Step mainly proxy values. Some of the social inputs are not formulated yet, but dummy data have been used in the current version of the model for illustrating how the model is intended to work – the model will later on be fed with real data from ongoing empirical work. Calculations for costs of policy options are rough estimations that will be refined in the Appraisal Step. Also, it might be possible to refine the benefit estimations due to new studies in the area.

More analytical information about the data approximations and transformations can be acquired after contact.

Contact: Jakob Walve, .