INCA Case Studies

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  1. INCA and catchment sensitive farming
  2. Modelling mercury in Loch Nagar
  3. Point and diffuse pollution in urban catchments
  4. Potential impacts of climate change on river water quality: a study of six UK rivers
  5. INCA modelling of metals downstream of mines

Case Study 1: INCA and catchment sensitive farming

Result ccharts for the River TestINCA has been applied to the River Test Catchment to test the likely effects of new catchment sensitive farming strategies in the UK on flow, nitrate, ammonia, total and soluble phosphorus, sediments and ecology (macrophytes and epiphytes). An important feature of the Test catchment is the relatively low slopes and the underlying geology of chalk which gives the catchment a relatively high base flow index of 0.94. This means that the groundwater is a very important component of the flow regime and will dominate the hydrology of the catchment. Land use is dominated by arable agriculture and grassland for animal production. A range of catchment sensitive farming techniques have been investigated using the model.

The effect of the scenarios on phosphorus and sediment concentrations along the River Test are fairly minimal, as shown in the Figure below.

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Case Study 2: Modelling mercury in Loch Nagar

A new version of INCA has been developed to assess the build up of mercury in catchments from atmospheric mercury deposition and also from terrestrial sources of mercury. The major issue is the release of methyl mercury into upland streams and lakes and the high concentrations of mercury in fish in northern European lakes.

Loch NagarThis is a serious problem in Sweden where many lakes have high mercury levels in fish and these are so high that the fish are toxic to humans if eaten.

The new version of INCA has been developed to simulate the build up of mercury on soils and the leaching of mercury into rivers and lakes.

The model has been applied to the Gardsjon catchment in Sweden and Loch Nagar in Scotland.

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Case Study 3: Point and diffuse pollution in urban catchments

The impacts of diffuse and point source pollution climate change on water quality in the Tame and Anker Rivers (sub catchments of the River Trent) has been assessed using the Results chart for the River ThameINCA suite of Models to simulate flow, phosphorus, and ecology.

The model has been used to assess the effects of different treatment methods for phosphorus at the STWs. The simulation below shows for the each reach boundary along the rivers and information on the means, plus and minus the standard deviations and the 95 percentile levels.

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Case Study 4: Potential impacts of climate change on river water quality: a study of six UK rivers

A modelling study has been undertaken as part of an EA project to assess the likely impacts of climate change on Water Quality across the UK.

A range of climate change (UKCIP) scenarios have been used to generate future precipitation, evaporation and temperature time series at a range of catchments across the UK. These time series have then been used to drive the INCA suite of flow, water quality and ecological models to simulate flow, nitrate, ammonia, total and soluble reactive phosphorus, sediments, macrophytes and epiphytes in the Rivers Tamar, Lugg, Tame, Kennet, Tweed and Lambourn. A wide range of responses have been obtained with impacts varying depending on river character, catchment location, flow regime, type of scenario and the time into the future.

Results for the river LambourneThe results from the project are complex as might be expected but consistent patterns are obtained and it is possible to make some statements about the likely outcomes:

  • In the lowland southern River Lambourn declining concentrations of Soluble Reactive Phosphorus (SRP) were predicted for winter months and increasing concentrations during summer and autumn months, caused by lower flows and hence reduced dilution, as shown in the Figure below. Theses changes in concentrations, together with changes in temperature and flow affects the ecology as well, with changes in macrophyte growth in summer months.
  • Sediments in the Lambourn are predicted to increase throughout the year but are particularly high in autumn after dry summers. The build up of sediments over dry periods followed by increased autumn flows seems the main mechanism here.
  • Results from the urbanized midlands River Tame show similar increased SRP levels in summer but higher increases in winter due to diffuse urban runoff. In the western and rural River Lugg (a tributary of the River Wye) the SRP is predicted to decrease in winter but increase in summer months.
  • Nitrate levels in the northern River Tweed show increased winter levels in upland headwaters as organic nitrogen is released and decreased levels in summer months due to drought and increased denitrification in the river. However, the lower Tweed shows increased nitrates in winter but the highest increases are in summer. This change is due to change in land use to agriculture and point source discharges in the lower reaches of the Tweed.
  • Nitrate levels in the south-western River Tamar has a similar response to the Tweed with higher nitrate in winter and lower summer nitrates in the upper reaches. In the lower reaches of the river, nitrates increase both in summer and in winter. The rate of change increases over time and also with the severity of the emission scenario for all the river systems.

Full details of the project are given in the EA report Potential Impacts of Climate Change on River Water Quality by Whitehead et al, 2008, Science Report - SC070043/SR1

The full report and summary are available as PDF files for download:

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Case Study 5: Inca modelling of metals downstream of mines

The River AbrudMining in the Transylvania region of Romania is a major issue now that Romania has joined the EU. Old mines going back to pre-Roman times have been polluting the rivers for over 2000 years. Moreover there is a desire to reopen and develop the mines to both clean up the polluting discharges and extract metals to boost the local economy.

We have undertaken an extensive study of the Aries and Mures River systems in Transylvania in Northern Romania where an old mine is having a major impact of river water quality.

Results for the River AbrudA new version of INCA has been created to simulated the fate and distribution of mine waste from old mines and the model has been applied to the Aries- Mures River System.

The INCA-Mine model has been used to assess the environmental improvements expected from a clean up operation at the mine as well as the environmental impacts of reopening this old mine.

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Contact us

Professor Andrew Wade a.j.wade@reading.ac.uk

Postal address:

Department of Geography and Environmental Science,
University of Reading,
Reading,
RG6 6AB,
UK.

Telephone:

 +44 (0)118 931 7315

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