Water Resource Associates
A network of consultants in water resources, water quality, hydrology, hydrogeology and flooding.
Review of the INCA model for the EA Decision Support Tool
Assessing the utility of the INCA suite of models for use in a new decision support tool being developed for the EA
Background
The EA is setting up a decision support system to assist with the making of environmental impact decisions as well as helping with the Water Framework Directive. As part of the process a review of available models was commissioned with a thorough review of the INCA model, in the first instance. This model is being developed for flow, nitrate, ammonia, organic and inorganic phosphorus, sediments, carbon and ecology (macrophytes, epiphytes and phytoplankton).
Grain size changes during a storm event
Scope of work by Water Resource Associates Ltd
The INCA suite of programmes have been developed over the past 5 years to simulate both terrestrial and aquatic systems and to model a wide range of catchments. The basic structure of INCA has been tested on 8 UK catchments and 10 catchments across Europe. The model is process based and therefore designed to cope with environmental change such as changes in land use, pollution levels and climate. The model seeks to incorporate the dominant mechanisms and processes operating and therefore does not include over complicated structures. However, because the model is process based, it does require user skill in applying the model and in interpreting model results. The software is written in C++ and utilises a menu driven interface as well as an output graphics and statistics package. INCA provides the following outputs:
- daily time series of flows, and water quality outputs, eg. nitrate-nitrogen and ammonium-nitrogen concentrations, at selected sites along the river;
- profiles of flow or water quality along the river at selected times;
- cumulative frequency distributions of flow and water quality at selected sites;
- table of statistics for all sites;
- daily and annual water quality loads for all land uses and all processes.
- 3D pictorial representations of flow and water quality
- time series plots of the soil and groundwater responses
- output times series for transfer to other analysis packages eg Excel
- procedures for saving modified parameter sets
- scenario simulation results presented graphically or as output files.
Results
In the review the model components are described and their utility evaluated for answering Environment Agency type policy questions. The issue of integrating the model into the Environment Agency Decision Support Tool (DST) is considered and a model range of options evaluated. Details of model calibration, validation, uncertainty analysis and model application are discussed and reviewed in the report. A large number of application results are presented to demonstrate the utility of the model.
Simulated Distributions of flow and water quality at Mildenhall on the Kennet for 1998
