MEDLI Version 2 is finally here!


After a long wait, MEDLI v2 has been released by the Queensland Government’s Department of Science, Information Technology and Innovation.

What is MEDLI?

MEDLI stands for the Model for Effluent Disposal using Land Irrigation. MEDLI is a computer model for designing and analysing effluent disposal systems for a wide range of rural and industrial industries, as well as Sewage Treatment Plants.

MEDLI predicts the fate of water, nitrogen, phosphorus and soluble salts, based on a series of inputs, including climate data for the specific area, effluent quality and volume, soil profiles – to a depth of 2.0m, and plant types. The model also allows for investigation into the optimal wet weather storage capacity, as well as type of irrigation and irrigation application rates, to ensure that your irrigation scheme is sustainable will not cause environmental harm.

 Where does it come from? And why is Version 2 exciting?

MEDLI was originally developed jointly by the CRC for Waste Management and Pollution Control, the Queensland Department of Natural Resources and the Queensland Department of Primary Industries in 1999. It is now managed and developed by the Department of Science, Information Technology and Innovation (DSITI), with Version 2 of MEDLI just released in June this year.

The new version of MEDLI is more user friendly and less subject to bugs and errors in the programming, and removes the need to go back and forth between several different menus, with easy to easy toggle screens.

How does it work?

The model requires a series of user inputs based on local climatic conditions, effluent quality and volume from the STP, or waste stream, the sizing of the wet weather storage, sizing of the irrigation area, soil profiles within the irrigation area, and plant type.

MEDLI uses location specific daily time step climate data for rainfall, temperature, pan evaporation, and solar radiation, and with the release of MEDLI v2 acquiring this data has never been easier! Climate data can now be accessed in the required format from the Queensland Government’s SILO climate database.

What can MEDLI do for you?

MEDLI is the program recommended by Queensland’s Environmental Regulator when applying for approval of your effluent irrigation scheme. But MEDLI can benefit you even before submitting an application for approval. When you have Simmonds & Bristow perform MEDLI modelling for your site we can help you to determine the following information for designing or assessing your irrigation scheme:

The required area of land needed to dispose of your effluent via irrigation (this varies based on your climatic conditions, the soil type of your site, and the vegetation, as well as the effluent quality).

If you have a set area of land, we can tell you how much of your effluent you will be able to dispose of via irrigation, including the appropriate daily application rate.

We can model the sustainability of your irrigation scheme to determine whether your effluent quality is likely to cause salinity accumulation within your soil profile, or whether there may be an excess of nutrients running off the site or leaching into the groundwater aquifer.

We can help to determine the appropriate sizing of your wet weather storage.

We can also determine the most sustainable crop or pasture to grow within your irrigation area, or we can work out what irrigation application rate is most appropriate for providing healthy crop/pasture growth.

Here’s a sneak peak of what the new release looks like:

And a sneak peak of the output summaries: