Hydrology innovation garnering international attention

By on 9 August, 2017

Alan Pearse, a 3rd year student at QUT, has created a new tool to better model surface water contamination.


Contaminated surface runoff is a known source of environmental degradation across Australia’s waterways and coastal habitats.

Nineteen-year-old Queensland of University (QUT) student, Alan Pearse, sought to create a new tool to better understand this phenomena. Pearse’s innovation, known as IDW-Plus toolbox, has improved the understanding of how land use within a watershed can be integrated with hydrology data to deliver a more refined understanding of the potential mobilisation and delivery of contaminants downstream.

The toolkit has already gained international attention, with United States Geological Survey hydrologists using it to study how natural hazards threaten America’s water resources, while the US Department of Agriculture has hosted IDW-Plus on its website for scientists to download and use (view the toolbox and test data here).

Pearse’s concern for the environment was a key motivator for the third-year student in his work on the project.

“Our past methods assumed that each section of land in a catchment contributed equally to the body of water at the end, but this isn’t the case,” Pearse said. “Some land may have more water pass through, or be closer to a stream where more water is likely to collect and reach the end of the line. These areas, therefore, have a greater impact.”

“IDW-Plus takes factors like these into account and gives us a far better understanding of what is ending up in our lakes and rivers, and eventually in our oceans.

“It also performs these calculations in a fraction of the time it took in the past.”

Six outputs from the IDW-Plus tool to characterise Euclidean distance and flow length to stream and outlet. From: Peterson and Pearse 2017.


At its core, the tool uses inverse distance weighting interpolation (IDW) and additional inputs, primarily elevation and land use, to calculate six watershed metrics that account for the Euclidean or flow length distance to the surface flow and outlet. The resulting output classifies grid cells based on their potential contribution to the surface flow, and as a result, delivery to an output location. With this knowledge, areas within a watershed can be classified by their potential to contribute contaminants at a more sophisticated level.

The toolbox is made for use within Esri’s ArcGIS platform. Esri Australia has awarded Pearce the 2017 Australian Esri Young Scholars Award, which saw him showcase IDW-Plus at the Esri User Conference in California in July.

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