Point Walter is a point in the Swan River, Western Australia. It is located on the southern shore and forms the western end of Melville Water. Point Walter is located in the suburb of Bicton and is on the opposite side of the river to the suburbs of Mosman Park, Peppermint Grove, and Dalkeith. Point Walter is notable for the sand bar that extends over 1 km into the river, sections of which often submerge under high water. It is the site of various cultural monuments and activities, including a war memorial avenue. Point Walter was named in 1827 by Sir James Stirling, in honour of his favourite older brother, Walter Stirling.
A bar in a river is an elevated region of sediment (such as sand or gravel) that has been deposited by the flow. Types of bars include mid-channel bars (also called braid bars, and common in braided rivers), point bars (common in meandering rivers), and mouth bars (common in river deltas). Bars are typically found in the slowest moving, shallowest parts of rivers and streams. The locations of bars are determined by the geometry of the river and the flow through it. Point bars form on the inside of meander bends in meandering river because the shallow flow and low shear stresses there reduce the amount of material that can be carried there. The excess material falls out of transport and forms the bar.
Uniquely, for the bar at Point Walter, sand build-up over the past decade or so has made the ‘island’ at the spit’s centre a permanent feature of the river. The ‘island’ is now home to 14 plant species – including eight that are native to Western Australia.
EarthCache Task
At the given coordinates you will find what we consider to be the perfect viewing point for the Point Walter sand bar. Parking is nearby as are a cafe and toilets. In order to prove your visit and claim the find, we ask that you email us the answers to the below listed questions. Please take a photo of yourself/selves through the structure with the sand bar in the background. You can walk along the sand bar to obtain some of your answers (although bare feet & shorts are recommended). We have included some waypoints to help you with these. Please be careful of your geo-kids and be sure to judge the conditions on the day yourself however.
Once we receive your answers & we get back to you, you may log your find & attach the photo you took.
Questions: (there is a range of correct answers to each question due to the tidal nature of the river. We have recorded what we consider to be the minimum and maximum, so anything between these will be accepted)
1) how long does the sand bar at Point Walter extend into the river,** At some points of the year the end of the bar may be fenced off due to bird nesting. Please do not disturb the birds, and instead provide your measurement up to the fence line and state this in your answers. Thanks**
2) approximately how wide is the sand bars permanent feature at its widest point (to the closest 1m)
3) approximately how deep below the water level is the submersed section of the sand bar (to the closest 100mm)
Bonus question: (not a requirement for the earth cache, but just for fun)
4) the first name of the artist that created the structure overlooking the sand bar, along with the meaning of the monuments' name 'Habibi' (you may need to google)
Happy Caching!