Integrated Catchment Model

Overview

Across the European Union there are concerns about a wide range of pollutants that affect water resource systems as well as environmental change such as land use change and climate change. With the EU Cap and Farming reforms there has been changing agriculture and land use, and this will continue into the future. Also, the Water Framework Directive will drive new policy over the next 10 years. Also climate change is beginning to alter hydrological regimes and temperatures and this will affect water resources, river ecology, agriculture, terrestrial ecosystems and land use. For example, nitrogen (N) in lowland and upland fresh water systems can cause eutrophication, leading to rapid aquatic plant growth. Such increases in growth are often viewed as a nuisance as certain plant species may grow at the expense of others and, within freshwaters, the microbial breakdown of the dead plant matter can lower oxygen levels which is detrimental to invertebrate and fish populations. The problems of freshwater eutrophication are usually associated with lowland, intensively farmed areas where fertilisers provide a significant source of N and P and/or urban areas where domestic and industrial effluent is discharged to the receiving watercourse and groundwaters.

Whilst management strategies have been implemented to control N and P in river systems, these have tended to address single issues: either diffuse or point sources, or upland or lowland areas. However, the N concentrations and loads in rivers reflect the integration of the catchment N sources: fertiliser inputs, atmospheric deposition and sewage discharges. Superimposed on these anthropogenic inputs are contributions from the vegetation and mineralisation (and subsequent nitrification) of organic N in soils. Furthermore, the combination of the multiple catchment N sources has a downstream effect, influencing the options for further water utilization and impacting the water quality of estuarine and marine areas. Thus, given the holistic nature of the N problem, an integrated management approach is required.

The INCA suite of models has been developed to support such an integrated approach.