The Pike Floodplain groundwater model has been developed as part of the South Australian Riverland Floodplains Integrated Infrastructure Program (SARFIIP). SARFIIP is a $155 million program funded through the Murray-Darling Basin Authority (MDBA) which aims to improve the watering and management of key River Murray floodplains in South Australia’s Riverland. By implementing managed inundation and groundwater manipulation of the Pike and Katarapko floodplains, the aim is to increase soil moisture availability to support native floodplain vegetation.
Historically, salinity investigations of the River Murray region have focused on the salt flux to the river, while neglecting the impact to the floodplain. The role of the Pike Floodplain model is to assess the salinity impact of works and measures on the floodplain. Building on the previously developed flow model of the Pike Floodplain, a solute transport model has been developed. The solute transport model is intended to be used to assess the ecological and environmental impacts and benefits of SARFIIP management options. Due to the scarcity of salinity data in the region, a quantitative calibration of the model was not practical and so a qualitative check of the model performance has been undertaken. Assessment of the model performance was undertaken using a number of criteria, including comparison to AEM data and ecological health data from the site.
Criteria have been developed which categorise conditions that are likely to be beneficial to, and similarly negatively impact, the health and recruitment of two tree types found on the Pike Floodplain. Python scripting has been used to determine the percentage of time the modelled water level and salinity meet the specified criteria over the benchmark period of 1975-2015. Comparison of these modelled results with on ground tree health surveys suggests that the shallow, low salinity areas in the model correspond to healthy vegetation on ground.