EXPERIMENTAL DATA ON RUNOFF MITIGATION BY MEANS OF MICRO-DAMS

With the aim of compiling the current state of knowledge on the effectiveness of micro-dams in reducing surface runoff and demonstrating an approach to consider the results in regulatory exposure assessment of plant protection products (PPP), knoell experts conducted an extensive literature review and published the results in a peer-reviewed scientific journal. A geometric mean reduction of runoff and erosion of 62 % (range: 42 %–90 %) and 73 % (60 %–90 %), respectively, was derived indicating the considerable potential of the micro-dams’ technique as a mitigation measure for PPP-entries from runoff-events into adjacent surface waters.

In regulatory exposure modelling, the curve number (CN) approach is used to predict the direct runoff response from rainfall of a drainage basin. The CN is an empirical parameter which is mainly based on hydrological conditions, land use and land treatment. Based on the collected data, it was concluded that the micro-dam technique can be taken into account in regulatory exposure assessment by reducing the default CN value by up to 11 %.

It was concluded that micro-dams significantly reduce the discharge of PPPs and that this reduction potential can be taken into account in exposure modelling either by adjusting the CN value or by implementing an additional reduction factor.

The literature review was funded by Bayer CropScience. For further questions regarding this study or our further services in the area of environmental fate and exposure please contact Dr Wolfgang Reiher, Head of Environmental Fate and Exposure.

Authors: Stephan Sittig¹ and Robin Sur²

¹knoell Germany GmbH, ²Bayer AG, Germany