Spatially Distributed Leaching Modelling (SDLM)

(August 2019)

The European Spatially Distributed Leaching Modelling initiative was started in 2019 by a group of interested scientists working in the area of spatially distributed modelling. The initiators come from public research institutes (Wageningen University & Research, Fraunhofer Gesellschaft), contract research institutes (Waterborn) and industry (ECPA companies) and are in dialog with representatives of European national regulatory authorities that are interested in the initiative.  

The goal is to establish a standard SDLM method to be used according to the FOCUS groundwater tiered approach (FOCUS, 2014, Sanco/13144/2010, version 3, 10 October 2014 ) where this is foreseen as Tier 3b.  It should also support groundwater monitoring which is included as Tier 4 in the FOCUS tiered approach.

The necessity for a harmonized framework for SDLM is also indicated in the publication of the SETAC EMAG-PEST GW working group where guidance on how to conduct monitoring studies is given (Gimsing, A.L., Agert, J., Baran, N. et al., J Consum Prot Food Saf (2019) 14(Suppl 1): "Conducting groundwater monitoring studies in Europe for pesticide active substances and their metabolites in the context of Regulation (EC) 1107/2009"). Therefore, this initiative is also welcomed by this SETAC working group as well as a number of regulators that are organised in the informal European Regulatory Network on Pesticide Groundwater Monitoring.

Note that, through this page, ESDAC intends to facilitate this initiative, as it is clearly linked to the FOCUS content available from ESDAC.


First SDLM Workshop, Ghent, 24 May 2019

On 24 May 2019, a workshop was held in Ghent. The workshop consisted of international experts in GIS and groundwater modelling and was attended by representatives from academia, regulatory authorities, research institutes, contract organisations and industry.  The workshop was convened by the SDLM initiators in response to resolutions passed at the 9th European Modelling workshop in 2018 in Copenhagen where it was stated that a dialog is needed on a spatial modelling framework for selecting appropriate monitoring sites, setting existing sites into context and requirements on input and output of appropriate spatially-distributed models .It was also concluded that version control is needed for high-resolution spatial databases for the EU. Due to the lack of guidance in this area the workshop was organized to discuss the necessity and a strategy to develop guidance to establish SDLM as a standard method following a harmonized and well-accepted approach.

(28 August 2019) The report for this workshop.

(03 December 2020) The presentations:

Privacy Statement: The persons mentioned in the Report of the workshop and in the presentations have given their explicit consent to have their names mentioned on this site.

Problem definition document available

(01 December 2020)

The problem definition document of the SDLM-working group is now available. This document describes the aim and scope of the working group. The working group will act under the umbrella of the SETAC Environmental Monitoring Advisory Group on Pesticides (SETAC EMAG-PEST). The main products of the working group will be a harmonised spatially distributed modelling framework (SDLM) including the data needed to run these models, and documents describing the use of the framework in regulatory assessments. The framework will serve higher tiers of the FOCUS groundwater risk assessment scheme. The framework will deliver the same exposure assessment goal as currently used in FOCUS groundwater, i.e. the 80th-spatial and temporal percentiles of the leaching concentration at 1-m depth. This exposure assessment goal is considered a conservative estimate of the real groundwater concentration. To ensure consistency of the tiered approach, the modelling framework will support all parameter refinements carried out at lower tiers. The modelling framework will support the selection and interpretation of groundwater monitoring studies. However, the framework will not deliver the actual groundwater concentration, because additional processes occur between 1-m depth and the depth of the groundwater wells. The Working Group will consist of member from academia, regulators and industry. The Working Group will deliver two years after the start of the project.

Download the document. Parts of this publication may be reproduced, providing the source is stated, in the form: "Tiktak A. et al. (2020), Spatially Distributed Leaching Modelling of Pesticides in the context of Regulation (EC) 1107/2009. Problem definition document, available at". Note that the authors of the document have given their full consent to have the document published on ESDAC.

Contact for the contents of this web page: VAN LIEDEKERKE Marc (JRC-ISPRA) <>