Summary - City of Gosnells

Wetlands Field Survey 83onto the floodplains below. The drains downslope from these floodplains should be redesigned to allowthe infiltration into the groundwater and nutrient stripping by vegetation in extensive but shallow,vegetated swales that mimic the original floodplains of the area.c. Palusplain mapped in DEC (2008b) where a change of classification to paluslope may be consideredSite 15 of the MKSEA study was located on a gentle slope that was mapped as a palusplain in DEC(2008b), but it was considered to be a paluslope on the data obtained in the current field survey. This isthe most well developed peat paluslope that has been identified locally and requires further study andcareful management to conserve its significant natural values.d. Upland mapped in DEC (2008b) where a change of classification to dampland may be consideredSite 27 of the MKSEA study was located in a shallow basin and was seasonally waterlogged. This areawas not mapped as part of a wetland in DEC (2008b) but was considered to be a dampland on the dataobtained in the current field survey. The hydrological factors maintaining this wetland are not clear andneed to be investigated in detail in order to manage the surrounding areas in a manner that is compatiblewith the conservation of this wetland.e. Sumpland mapped in DEC (2008b) where a change of classification to palusplain may be consideredUFI 8050 is mapped in DEC (2008b) as a sumpland. The area where this wetland is located is thelowest lying area in Precinct 1 and there is obviously a high watertable in this area (probably due toseepage from the base of the adjoining dunes of Bassendean Sands onto the Pinjarra Plain surface in thevicinity of UFI 8050. There are small sumplands in this area.However, these sumplands appear to havebeen excavated by landowners for use as ornamental ponds, and the fringing vegetation is degraded tocompletely degraded. The sumplands are interconnected by excavated channels to two drains (one ofwhich conveys water north via BFS 387 to Yule Brook, and the other west to Bickley Brook).The current investigation showed that the vegetated area of UFI 8050 is a palusplain (seasonallywaterlogged flat). It comprised Corymbia calophylla low forest over Kingia australis and mid-denselow shrubs in which about half of the species were obligate wetland plants.As with other areas of the MKSEA where there is a boundary between the Bassendean Sands and thePinjarra Plain, this area requires hydrogeological study to accurately map the wetland to define anappropriate buffer zone above the wetland and to develop a plan to restore the hydrological regime inthis area.f. Creeks that were not indicated in DEC (2008b)There was a small watercourse mapped in the current survey that extended from the UFI 7632 damplandto Yule Brook via UFI 7635. Part of the upper reaches of this creek were modified into an excavateddrain. However, the creek retained its natural form over much of its course.There was also a drain that extended from the UFI 7633 sumpland to Yule Brook via Coldwell Rd. Thisdrain was aligned along the route of a pre-existing creek in the area.A drain north-west of wetland UFI 7800 was also probably aligned along the route of a pre-existingcreek in the area.g. Uplands where no changes to the DEC (2008b) classification were recommended in the current surveyMKSEA Sites 22, 23, 24, 25 and 29 were located in dunes of deep, well-drained Bassendean Sands.These areas were not mapped as wetlands in DEC (2008b), which was confirmed in the current fieldsurvey.Tauss, C. and Weston, A.S. (2010). The flora, vegetation and wetlands of the Maddington-Kenwick Strategic Employment Area.A survey of the rural lands in the vicinity of the Greater Brixton Street Wetlands. Report to the City of Gosnells, W.A. Version 18.04.10