UK Drainflow modelling
The Chemicals Regulation Division (CRD) have released a new tool to assist in UK-specific higher-tier drainflow modelling. The tool exists as a spreadsheet that allows the calculation of Predicted Environmental Concentrations (PEC) in surface water following drainage in UK conditions. The spreadsheet automates the creation of input files for the 12 main UK scenarios (a combination of 4 soil scenarios and 3 weather scenarios), then running the simulations in the MACRO model for 20 years and processing the output files to calculate the annual maximum PECs.
This tool proves to be a significant step forward with regard to harmonising the modelling submitted by different applicants, however, use of the tool is not always easy. Firstly, users will need access to a 32-bit PC or virtual machine, as the tool uses MACRO 4.3, which historically runs on 32-bit computers. CRD is planning to develop a future update that uses one of the later MACRO 5 versions, though this may take some time. Secondly, some risk assessments can require a fourth weather scenario to be modelled (e.g. when assessing applications to maize and grassland) and this is not currently covered by the tool being developed by CRD.
Previously, the assessment required spatial statistics for calculating the overall percentage of exceedances: Geographical data in SEISMIC (NSRI) or alternative GIS software was used to calculate the crop distribution across the drained soil types in the UK. It is no longer required to present the spatial statistics.
Enviresearch automated approach for standard drainflow assessments
Enviresearch has been providing higher-tier drainflow assessments ever since the start of the company 15 years ago. Over time we have developed systems for automating our processes. Our in-house drainflow modelling tool is optimised for maximum efficiency:
- Fully automated drainflow assessment from input of basic substance properties to creating the reporting tables
- Dedicated 32-bit server to speed up model simulations
- Cropping statistics are included for all crops listed in SEISMIC
- Covers 20 UK scenarios (CRD approved), including the very wet weather locations