Abstract: Development of long-term N and S deposition scenarios for the demonstration catchments for use in WP5
Long term sulphur and nutrient deposition scenarios were generated for 8 REFRESH demonstration catchments and selected sub-catchments as part of WP1 (Task 2.3). Detailed projections of future pollutant deposition are required to evaluate their impacts on functioning of aquatic ecosystems and to develop strategies for ecosystem management at the catchment scale. The core dataset used to generate the deposition scenarios was provided by EMEP (European Monitoring and Evaluation Programme, http://www.emep.int/), using a combination of measured and modelled emissions and meteorological data and a chemical transport model developed at the Meteorological Synthesizing Centre - West (MSC-W). Deposition forecasts were made to 2020 and based on the Current Legislation Estimate (CLE), Gothenburg Protocol.
The completion of Task 2.3 (Deliverable 1.10) also required data on current land use and scenarios of future land use, as the extent of woodland is known to enhance deposition inputs through scavenging of pollutants. This was provided on a country-by-country basis following the completion of Deliverable 1.8. To ensure appropriate integration between work packages, the modellers in WP5 requested deposition scenarios for total, reduced and oxidised nitrogen and sulphur deposition and wet/dry fractions. A comparison of modelled fluxes across the demonstration catchments shows that the dry deposition flux is generally lower than the wet deposition flux, although the pattern varies between chemical species and over time. For N species, dry deposition is modelled as making the most important contribution to total deposition in La Tordera. The effect of changing forest cover under the different land use scenarios has a noticeable impact on the deposition of NOx in the Beysehir, Dee and Thames catchments, and particularly in the Tarland sub-catchment. For NHy, the scenarios appear most important in the Thames and, again, the Tarland catchments. Elsewhere, the change in percentage forest cover under the different land use scenarios is too small to have a noticeable effect on the magnitude of dry, and hence total, deposition.
This is an internal deliverable, the main purpose of which is to provide the modellers in the demonstration catchments with nitrogen deposition scenarios for model paramaterisation. The deliverable provides a background to the data sources used in the task and a detailed description of the processing of this input data. A more practical guide to using the output data is also included in addition to a guide to the generation of the output.
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