eWater Source at WA’s Harding Dam

Using eWater Source and 32 climate projections, Water Corporation identified a significant decline in Harding Dam reliability under future climates.

The analysis revealed that longer drought sequences, not average rainfall change, pose the greatest risk to supply. The findings will directly inform future water planning and investment decisions in the Pilbara.

Water Corporation, in collaboration with the Western Australian Department of Water and Environmental Regulation (DWER) and the Australian Bureau of Meteorology (the Bureau), assessed climate change risks to Harding Dam, the primary water source for the West Pilbara Water Supply Scheme.

By combining the Bureau’s National Hydrological Projections with integrated modelling in eWater Source, the study translated climate uncertainty into clear insights about future water supply reliability.

The Challenge

Water Corporation has been working with DWER and the Bureau to understand how the Australian Water Outlook service, specifically the National Hydrological Projections, can be applied to assess climate change presents to the future reliability of the Harding Dam.

They found that planning water supply in the Pilbara was difficult due to:

• Highly variable, cyclone-driven rainfall
• Increasing temperatures and evaporation
• Deep uncertainty in future climate conditions

Harding Dam is particularly sensitive because it depends on infrequent, high magnitude inflow events, while experiencing high evaporation losses.

Water Corporation needed to move beyond historical analysis to understand future reliability under climate change, assess risk across a wide range of scenarios and ultimately identify adaptation pathways.

The Approach

Water Corporation developed an integrated modelling framework in eWater Source that linked:

• Rainfall-runoff processes
• Dam storage and evaporation dynamics
• Water supply demand and operational rules

Water Corporation generated multiple model simulations to test how the system behaved under different combinations of historical climate conditions (1940-2020) and the 32 future climate projections from the Bureau’s National Hydrological Projections to 2060.

For the Water Corporation, the undertook a second round of modelling to test more evolved options which has helped their asset managers to understand the supply capacity of the dam and inform the assessment of operational and supply options, including the viability of seawater desalination.

Using eWater Source, the team were able to run large ensembles of scenarios, capturing uncertainty and testing system response under a wide range of plausible futures.

Key Insights And Results

One of the key insights from the project was the modelling.

Using eWater Source, the modelling projected a noticeable decline in the proportion of time Harding Dam could reliably supply the West Pilbara Water Supply Scheme (link to scheme).

Applying the National Hydrological Projections with the water balance modelling found a significant reduction in supply reliability in future years, primarily due to extended drought duration.  

Further analysis revealed that:

• Average rainfall changes alone do not explain system performance
• Timing, sequencing, and variability of rainfall are critical
• System reliability depends on meeting key inflow thresholds during wet seasons

Source enabled Water Corporation to:

• Build end-to-end models linking climate, hydrology, and water systems
• Run multiple scenarios and climate projections efficiently
• Evaluate system performance under uncertainty
• Test operational and infrastructure options

eWater Source provided the critical capability to translate climate projections into actionable insights for water supply reliability and planning.

Next Steps

Water Corporation is now undertaking a long-term water supply strategy together with detailed asset planning for the West Pilbara scheme. eWater Source and the BOM’s National Hydrological Projections will provide key tools and data to support this critical work.

The Western Australian Government is committed to ensuring water management and planning reflects the values of the communities they serve,  The  key insights and in-depth evaluation,  enable more informed decision-making in water management for the people of the Pilbara  and ensures the continued strategic investment in climate resilient water systems across the state.

More information on this work and the National Hydrological Projections data set is available at: Application of projections_ Harding Dam supply reliability.pdf