Early-stage urbanization drives critical sediment production

Sediment production is often intensified in peri-urban areas as landscapes transition from predominantly rural to urbanized conditions. This transformation alters hydrological and sediment dynamics, which are complex and remain poorly understood, particularly during the process of urbanization. There is a need to begin systematically monitoring the impacts of urbanization on sediment production and transport. This study focused on monitoring suspended solids concentrations and loads in stormwater drainage systems over six months in Officer, Melbourne – a peri-urban area experiencing rapid urban development. Using low-cost automatic monitoring stations developed by our research team, we collected data across sites with different stages of urbanization, ranging from early construction to fully developed areas.

We found that during storm events, mean concentrations of suspended sediments in early urbanization stages can reach up to 100 times those observed in mature urbanized areas. Most importantly, suspended sediment yields in early-stage urbanization areas were up to 10 times higher than in fully developed areas, despite lower runoff volumes. Sediments from early stages of development were also finer than sediments from later stages. These high loads of fine sediments present increased risks to receiving water bodies, such as streams, bays, and wetlands, due to their ability to transport pollutants over long distances and contribute to environmental degradation.

The findings highlight the value of combining innovative monitoring technologies with geospatial and time series analysis to better understand sediment dynamics in a complex and rapidly urbanizing landscape. Additionally, the findings underscore that erosion and sediment control measures are vital, particularly during the early stages of urbanization, requiring proactive management throughout this process to mitigate fine sediment impacts and protect downstream waterbodies, ensuring sustainable growth in peri-urban areas.