County administrative board of Östergötland conducts assessments of regional waters and implements relevant measures to achieve the Water Framework Directive (WFD) objectives. The assessments and recommendations are based on current status of water bodies but those may change with changing climate. The current level of effort may be insufficient, or, could be directed more efficiently if the future impact can be predicted.
The climate indicators provide consistent, high-quality data showing the impact of climate change on nutrient loads and concentrations for the whole study area. Resources available at the country board can thus be allocated to preparing for the future rather than processing large amounts of climate data for various scenarios. The indicators can be used in planning for future water quality for drinking, swimming, fishing, and the environment.
An algal bloom
Case Study Description
County administrative board of Östergötland conducts assessments of regional waters and implements relevant measures to achieve the WFD objectives. There are many lakes, rivers and coastal areas in the region which currently do not reach a good status in terms of nutrients. Algal blooms are common. Internal loads from lake sediments are also a problem.
The assessments and recommendations are based on current status of water bodies but those may change with the changing climate. The current level of effort may be insufficient, or, could be directed more efficiently if the future impact can be predicted. Measures are expensive and need to be prioritized in order to use the available resources effectively.
The climate impact indicators developed for a coarser resolution were used to estimate the impact on nutrient concentrations and nutrient status at the local scale. The assessments and recommendations on how to improve the assessed status of water bodies are now based only on the current status, availability of resources, and priorities. The assessed status may change in the future with the changing climate.
The current plan (see below) may then be insufficient, or, monetary and other resources could be directed more efficiently if the future climate impact can be included into the planning. Remediation measures are expensive and need to be prioritized in order to use the available resources effectively. Current and future nutrient status should guide decisions on how to best appropriate the available resources in order to improve or maintain the nutrient status in the county.
Using nutrient indicators from SWICCA enables us to focus our resources on evaluating the implications for ecological assessments the client is responsible for. It also allows us to better illustrate local and pan-European variations of various impacts, even those that are not directly requested by the client.
County administrative board governs an area of 10 562 km2. There are several large lakes in the area that significantly increase the water residence time before it reaches the coastal zone. A change in the inputs to surface waters may take many years before it is fully reflected at the output point to Baltic Sea. The client is primarily concerned with climate change on time scales ranging from 20-30 years from now until 100 years from now.
Purveyor visits client frequently to discuss the steps of the project and to confirm that the project satisfies the needs of the client. In-person meetings will be conducted on a quarterly basis or more frequently if needed. Detailed notes will then be circulated among all participants after each meeting to provide a summary of decisions, questions, and any other issues. Electronic communication will be used between the meetings to assure an uninterrupted flow of data and information between the client and the purveyor. Results are delivered as WMS layers which are easy to integrate with other information in client's ordinary work tools.
We have extracted water quality indicators: phosphorus and nitrogen concentrations and loads. The assessment of the ecological status is based on phosphorus concentrations.
The investigation may reveal other connections between the climate data, hydrological data, and water quality characteristics that may define local indicators.
Step 2: Apply the change to local data using downscaling techniques. Downscaling the data will be critical due to spatial and temporal differences between the local and pan-European data sets resolutions. Local data can be time series simulated by a local water quality model, observations, or statistics used in the assessment process. A local water quality model might be needed to simulate the impact of future loads on lakes and coastal zones if detail evaluation is needed.
Step 3: Derive a map of future concentrations and loads. Results from (2) will be processed to a WMS map that client can use together with their existing data. Both long-term and seasonal data will be displayed.
Step 4: Derive a map of expected compliance with water quality standards (WMS). In Sweden, nutrient concentrations are compared to reference conditions (local data). Streams are then categorized into 5 nutrient status categories based on the ratio of the observed (or simulated) concentration and a reference concentration. A different country-specific assessment method might require other steps.
Step 5: Develop a vulnerability map (WMS). This map would show water bodies where nutrient status will be degraded. Local data with current classification of streams based on nutrient status are utilized in this step.
Step 6: The possible impacts of climate change (step 5) can be considered in the plan of measures. Critical potential sources contributing to increased nutrient transport in vulnerable areas can be identified and nutrient measures prioritized.
Using SWICCA interface has saved significant resources in the initial processing and evaluating various climate scenarios and their impact on average or seasonal nutrient concentrations. Once the interface was properly functioning, the actual download was very intuitive. It also helped while communicating the scenarios and their meaning during our meetings with the client.
The relatively coarse resolution limits the usability of the water quality indicators on local scale to (1) only the main streams in E-HYPE catchments (2) in the areas where E-HYPE delineation is correct.
To finish the study in its entirety, we would need the following indicators:
- Concentrations and loads that enter the main stream from local streams
- Concentrations and loads that enter the local streams from soil layers/tile drain
- Background concentrations (natural conditions with limitations on anthropogenic impact)
- Median concentrations in the main stream and local streams for different flow ranges (e.g., above 95th percentile, between 90th and 95th percentile, etc.)
Indicators A. and C. would be used directly in the work flow. They would allow determination of the future ecological status and the risk of degradation for all streams in the area. Indicators B. and D. would allow better investigation of the processes that are driving the change in concentrations. Currently, there is no way to determine under what conditions the increase in concentrations occurs. Since different measures can target different flows, it would be important to know whether to focus on low flows, median flows, or high flows.
Water quality indicators were not available until later in the study. This has affected our progress not only with respect to the timeline but also with respect to what can be accomplished. At the beginning, the data providers were open to extracting additional indicators. However this was prior to our discussions with the client. It may no longer be possible to receive any of the indicators that our study shows would be needed.
Step 2 from our workflow forms a basis for the rest of the case study. The steps 3-5 are well defined processes that were further refined during this study. Communication is very important at the initial stages of the project when the overall approach is getting established.
Traditional method for assessing ecological status of surface waters relies on direct measurements of water quality constituents. This method only addresses current situation and sources. The client realizes that climate change may affect water quality in the water bodies under their responsibility, which in turn could impact the efficiency of the planned measures or the priority of actions being decided.
"SWICCA indicators provide consistent, high-quality data showing the impact of climate change on nutrient loads and concentrations for the whole study area. Resources available at the country board can thus be allocated to preparing for the future rather than processing large amounts of climate data for various scenarios". - Sofia Bästviken, County administrative board of Östergötland.
While statistical methods can be used to indicate a trend in concentrations, the cause of the trend cannot be identified with certainty. Any measures proposed to improve the water quality are specified based on the current situation. There is a critical need to adapt the process to climate related changes. SWICCA provides an easy direct access to these changes in water quality for larger streams.
The climate change needs to be taken into account to properly guide the distribution of funds in implementing the measures. Both current and future water quality should be taken account when making decisions on how to appropriate the resources available to the client. While the future is uncertain, managers need to understand the possible risks to make an informed decision.
The uncertainty in predictions when different models predict different impacts makes the climate adaptation more difficult. However, the efforts can be then focused on areas where the certainty is higher and the models agree as those are likely areas where the change will be the most pronounced.
The client is responsible for implementing the EU Water Framework Directive in a local county. Excess nutrients present in surface water due to anthropogenic influences cause deterioration of water quality; this is reflected in the assessment of nutrient status guided by WFD. Based on the sources of nutrients and other issues identified within the county area, the county selects appropriate remediation projects. The measures are accessible from here.
There is a wide variety of measures proposed to address not only phosphorus concentration but also other pollutants. The measures range from liming through building phosphorus removal ponds to removing fish migration obstacles to promote healthy aquatic communities. The risk to the existing ecological status will be taken into account when determining priority areas.
Value added by Copernicus Climate Change Service:
Aerial photo showing algae blooms in the Östergötland archipelago (photo by Swedish Coastguard)