Non-effluent water storage modelling using MEDLI

Abstract

MEDLI (Model for Effluent Disposal using Land Irrigation) is a Queensland Government-owned model (now managed by DES) that is the benchmark water balance model for wastewater reuse applications in Australia. MEDLI lends itself to further investment as a vehicle for delivering other research outcomes and new modelling capabilities. There is a need for MEDLI to be supported and maintained, and there are opportunities to expand its capabilities with reasonable additional investment.
MEDLI is designed for agricultural wastewater reuse applications but can, and has been, ‘tweaked’ to perform other tasks that have demonstrated MEDLI’s versatility and potential. Modelling of freshwater storages is an application well-suited to MEDLI. The most cost-effective and intuitive way to accommodate non-effluent water (freshwater) storage modelling is to program the feature into MEDLI.
Freshwater storage modelling requires additional inputs, algorithms and outputs, depending on the objective. Nutrient loading rates from different catchments and faecal deposition from livestock and wildlife (especially waterbirds) may be required for irrigation and water quality scenarios. Catchment modelling can be adapted from the MEDLI feedlot model. Nutrient loadings can be predicted from published values.
For biosecurity and pathogen risk assessment applications for the poultry industries, habitat attraction for waterfowl and prediction of waterfowl abundance will be required i.e. modelling when waterbodies will dry up during drought and waterfowl will flock to permanent water supplies on or near poultry arms, increasing the risk of disease transmission, including Avian Influenza.
DAF needs MEDLI as a research and regulatory tool and a vehicle for delivering outcomes, and DES needs DAF’s commitment and support to ensure MEDLI remains operational long-term. External funding for MEDLI is more justifiable once the freshwater storage framework is in place.