GEOMORPHIC WETLANDS SWAN COASTAL PLAIN DATASET REQUEST FOR MODIFICATION LOT 123 MORTIMER RD CASUARINA Prepared by: Mia Harris BSc Bioscience Pty Ltd TABLE OF CONTENTS 1. INTRODUCTION ...................................................................................................... 4 1.1. Background .......................................................................................................... 4 1.2. Site Description .................................................................................................... 4 2. WETLANDS ............................................................................................................... 6 2.1. Definition .............................................................................................................. 6 2.2. Vegetation and Soil Type .................................................................................... 7 2.3. Groundwater Levels and Soil Type ................................................................... 9 2.4. The Classification of Wetlands......................................................................... 11 2.5. Field Verification ............................................................................................... 13 3. DESKTOP STUDY .................................................................................................. 13 3.1. Climate ............................................................................................................... 13 3.2. Geomorphic Dataset .......................................................................................... 16 3.3. Topography ........................................................................................................ 17 3.4. Site Geology and Geomorphology ................................................................... 19 3.5. Hydrogeology ..................................................................................................... 20 3.6. Vegetation .......................................................................................................... 22 3.6.1. Vegetation Complexes and Floristic Community Types ........................ 22 4. WETLAND ASSESSMENT FIELD WORK ........................................................ 23 4.1. Hydrology and Soil Investigations ................................................................... 23 4.2. Soil Profiles ........................................................................................................ 24 4.3. Hydrological Data ............................................................................................. 24 4.4. Soil Data ............................................................................................................. 27 4.5. Vegetation .......................................................................................................... 28 4.5.1. Detailed Site Investigation ......................................................................... 28 4.5.3. Vegetation Condition ................................................................................. 31 5. FINDINGS ................................................................................................................ 32 5.1. Geomorphic Classification ............................................................................... 32 5.2. Purpose and Limitations of Bulletin 686 ......................................................... 33 5.3. Results of Bulletin 686 ....................................................................................... 34 6. DEVELOPMENT POTENTIAL ............................................................................ 36 7. CONCLUSIONS ...................................................................................................... 37 REFERENCES ................................................................................................................. 39 I ntegrating R e s o u r c e M a n a g e m e n t 2 APPENDIX 1: Soil Profiles ............................................................................................. 39 APPENDIX 1: Soil Profiles ................................................................ ............................. 40 APPENDIX 2: Guidance 51 Survey Results .................................................................. 45 APPENDIX 3: Bulletin 686 ............................................................................................. 47 APPENDIX 4: Historical aerial photographs ............................................................... 53 TABLE OF FIGURES Figure 1: Location of subject site ..................................................................................... 5 Figure 2: Average Annual Rainfall 1972-2010 .............................................................. 14 Figure 3: Rainfall over the study period ........................................................................ 15 Figure 4: Annual rainfall anomaly for south-western Australia ................................. 16 Figure 5: Geomorphic Wetlands Dataset Map ............................................................. 17 Figure 6: Topography and groundwater contours ....................................................... 18 Figure 7: Soil Geology ..................................................................................................... 20 Figure 8: DoW Peel Main Drain – Sub drain O ............................................................ 21 Figure 9: DEC Bush Forever site locations ................................................................... 22 Figure 10: Bore Locations ............................................................................................... 24 Figure 11: Groundwater levels October 2007-May 2011 ............................................. 25 Figure 12: Annual average groundwater levels of surrounding monitoring bores ... 26 Figure 13: EPA Guidance 51 Quadrat and Transect Locations .................................. 29 Figure 14: Bray and Curtis nearest neighbour pattern analysis dendrogram ........... 31 Figure 15: CCW and surrounding properties ............................................................... 35 I ntegrating R e s o u r c e M a n a g e m e n t 3 1. INTRODUCTION 1.1. Background Mr Ivan Yujnovich commissioned Bioscience to undertake an environmental study of his land at Lot 123 Mortimer Rd, Casuarina (32.235ºS, 115.853ºE). The purpose of the work was to make a detailed examination of the hydrology, soil and vegetation, upon which to determine the appropriateness of the Conservation Category Wetland (UFI 6679) classification to the north of the property. A wetland reclassification request was originally lodged on May 22nd 2006, albeit under different (then) Department of Environment guidance operating at the time. The request was rejected largely due to insufficient long term data and insufficient detail. DEC subsequently issued more detailed guidelines for making requests to modify the geomorphic wetlands dataset. This report goes well beyond the detail required of current guidelines, and represents 6 years of study and observation at the site. 1.2. Site Description Lot 123 is located approximately 33 km south of Perth and 9 km east of the coast (Figure 1). The property covers an area of approximately 45 hectares, the vast majority of which is vegetated with Banksia open woodland. It lies within the City of Kwinana and is surrounded by a mix of rural and special rural properties to the north, east and west with Mortimer Road defining the southern boundary. Under the Metropolitan Regional Scheme it is zoned Urban Deferred. The majority of the surrounding land has been cleared of native vegetation, either completely, or parkland cleared. I ntegrating R e s o u r c e M a n a g e m e n t 4 Figure 1: Location of subject site I ntegrating R e s o u r c e M a n a g e m e n t 5 2. WETLANDS 2.1. Definition The definition of wetlands of the Swan Coastal Plain as used in the Environmental Protection Act and Regulations is contained in Hill et al (1996). In particular, Chapters 2 and 3 address at length the basis of defining and geomorphically classifying wetlands, considering both internationally accepted definitions and the specific regional setting of the Perth area. ―Wetlands in Western Australia have been defined locally as: areas of seasonally, intermittently or permanently waterlogged soils or inundated land, whether natural or otherwise, fresh or saline, e.g. waterlogged soils, ponds, billabongs, lakes, swamps, tidal flats, estuaries, rivers and their tributaries” (ibid, p.32) The key words are waterlogged and inundated, and the definition recognises that such conditions may be permanent or intermittent. Unfortunately waterlogged is not a precise technical term and as such is subject to interpretation. Intermittent is also indefinite in that it does not define an appropriate time scale. Hill et al (1996) does provide assistance with interpretation with further description and illustrations. In particular, Figures 2.2, 2.3 and 2.5 show the authors relate inundation and waterlogging to groundwater levels. Figure 2.2 clearly shows that wetlands extend to the area where there is seasonal saturation of soil by capillary rise of groundwater to the surface. Figure 2.3 clearly shows that the upper extreme of the range of groundwater levels in pertinent to defining wetlands. “The term „waterlogged‟ is equivalent to saturated and is used as distinct from inundated in the following way in this classification: Waterlogged: those soils that are