Mountain Creek is a small subcatchment of the Mooloolah River catchment. Over time, urbanisation in the lower reaches of this catchment changed the way the water flowed in the catchment, resulting in flood mitigation works being undertaken in 1992 to protect residential areas. This resulted in a new channel in the creek being created and being stabilised with rock and concrete, which stopped the erosion in this area but moved the erosion elsewhere.
These changes to the creek reduced the stream length from a previous length in this section of 1.4km to approximately 1km. These changes increased the stream slope, resulting in increased velocities during rainfall which destabilised the system and resulted in more and more material being taken from the banks and sent off downstream.
Since then, as the creek has re-established its equilibrium, the creek has deepened and widened, contributing to the erosion we see today. The erosion is also natural and occurs as waterways change over time.
Key takeaways from this EarthCache:
- Erosion is something that can impact everyone - at this creek, if the erosion were to continue, it could easily impact people living nearby.
- The speed and direction of water flow impacts the amount of erosion and what part of the creek will be eroded.
- When the creek deepens, it slows the water, resulting in different parts of the creek being eroded.
- When water courses change length (either by natural or man-influenced means) how prone the surrounding area is to erosion will impact the overall geological makeup of the area.
To find this EarthCache, answer the following questions and send them to the cache owner.
- Looking around the site, do fallen trees decrease or increase the erosion at this site?
- How does the erosion at this site impact your visit to this area?