Ecohydrological Conceptualisation of the Fortescue Marsh Region
Yüklə 12,45 Mb. Pdf görüntüsü
|
- Bu səhifədəki naviqasiya:
- 4.2.4 Surface water catchments
- Catchments contributing to the eastern fringe of the Fortescue Marsh
- Catchments contributing to the southern fringe of the Fortescue Marsh
- Catchments contributing to northern fringes of the Fortescue Marsh
- 4.2.5 Flood regime
- Figure 4-8: Conceptual flooding and drying dynamics of the Fortescue Marsh groundwater with rainfall cumulative deviation plot (BOM Wittenoom gauge)
- 4.2.6 Hydrogeological setting
Scientific Name Common Name Conservation status (WA) Population (no. of individuals) Season Monitoring Period Acanthiza robustirostris Slaty-backed Thornbill none resident 2008 - 2008 Anas gracilis Grey Teal none 0 – 28,312 unknown 1999 - 2003 Anas superciliosa Pacific Black Duck none 0 – 63,560 unknown 1999 - 2003 Anhinga novaehollandiae Australian Darter none 0 – 1,474 unknown 1999 - 2003 Ardea pacifica White-necked Heron none 0 – 2,148 resident 1999 - 2003 Ardeotis australis Australian Bustard Priority 4 (WA) resident 1998 - 2008 Aythya australis Hardhead none 0 – 76,746 resident 1999 - 2003 Burhinus grallarius Bush Stonecurlew Priority 4 (WA) resident 1998 - 2008 Chlidonias hybrida Whiskered Tern none 0 – 19,601 unknown 1999 - 2003 Conopophila whitei Grey Honeyeater none resident 2008 - 2008 Cygnus atratus Black Swan none 0 – 17,535 i resident 1999 - 2003 Dendrocygna eytoni Plumed Whistling-duck none 0 – 17,500 resident 1999 - 2003 Emblema pictum Painted Firetail none resident 2008 - 2008 Eremiornis carteri Spinifexbird none resident 2008 - 2008 Falco hypoleucos Grey Falcon Schedule 1 (WA) resident 1998 - 2008 Himantopus leucocephalus White-headed Stilt none 0 – 24,837 unknown 1999 - 2003 Malacorhynchus membranaceus Pink-eared Duck none 0 – 11,157 unknown 1999 - 2003 Neopsephotus bourkii Bourke's Parrot none resident 2008 - 2008 Pezoporus occidentalis Night Parrot Schedule 1 (WA) 18 unknown 2005 - 2005 Phalacrocorax melanoleucos Little Pied Cormorant none 0 – 5,991 unknown 1999 - 2003 Phalacrocorax sulcirostris Little Black Cormorant none 0 – 27,630 unknown 1999 - 2003 Poliocephalus poliocephalus Hoary-headed Grebe none 0 – 12,673 unknown 1999 - 2003 Threskiornis spinicollis Straw-necked Ibis none 0 – 16,947 unknown 1999 - 2003 4.2.4 Surface water catchments Catchment areas contributing flows to the Marsh include (Map 4-01): Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 92 Our ref: FM-EcoConcept_v8.docx downstream portions of the Fortescue River catchment. The majority of this catchment extends beyond the study area; downstream portions of the Weeli Wolli Creek catchment, on the alluvial fan of this creek system. The majority of this catchment extends beyond the study area; Koodaideri Creek; Chuckalong Creek, located between the Weeli Wolli Creek to the west and Mindy Mindy Creek to the east; Coondiner Creek and Mindy Mindy Creek; BHP Billiton Iron Ore Roy Hill East; Goman/ Sandy Creek; Christmas Creek; Kulbee Creek; and Kulkinbah Creek. The Marsh itself consists of two basin areas (east and west) s eparated by a slightly more elevated divide. For each of these catchments, the relative contribution of different EHUs to the catchment area provides an indication of surface water processes (source, transfer and receiving) operating within the catchment (Map 4-01). This also provides a basis for comparing different catchments. For example, the Weeli Wolli Alluvial Fan sub-catchment to the south of the Marsh comprises mostly lowland sandplains, with gently undulating surfaces, significant infiltration losses and low surface water runoff. In contrast, the Goman/Sandy Creek sub-catchment to the north of the Marsh includes a combination of upland source and transitional areas with short flowpaths and high runoff, and lowland alluvial plains with higher infiltration and lower surface runoff. Each of the study area catchments are described in more detail as follows. Catchments contributing to the eastern fringe of the Fortescue Marsh A relatively small portion of the Fortescue River catchment, being 2,152 km 2 of the total catchment area of 16,281 km 2 , lies within the study area to the east of the Marsh (Map 4-01). This area can be partitioned into two distinct sub-areas, north and south of the Fortescue River respectively. The northern sub-area contains areas of EHUs 1 and 2 - upland source areas comprising hills and dissected slopes and plains. Surface water runoff from these areas is directed via dendritic drainage networks through short flow paths that terminate in the Fortescue River. The southern sub-area consists of lowland alluvial plains and sandplains (EHUs 5 and 6), which constitute part of the Fortescue River alluvial fan. These EHUs are associated with poorly defined drainage patterns, high infiltration rates and minimal runoff; although, some local scale surface water redistribution may occur. The Fortescue River including its associated floodplain is classified as a lowland major channel system (EHU 8). Catchments contributing to the southern fringe of the Fortescue Marsh Catchments that lie on the southern fringe of the Marsh include the Koodaideri Creek, Weeli Wolli Alluvial Fan, Chuckalong and Mindy Mindy/Coondiner Creek sub-catchments. These sub-catchments drain from the Hamersley Range and extend across the wide, flat plains between the base of the Hamersley Range and the Marsh. The Chuckalong catchment is a small catchment between the Weeli Wolli Alluvial Fan catchment and the Mindy Mindy / Coondiner Creek catchment. Examination of the 5 m DEM revealed that the Mindy Mindy Creek catchment is a sub-catchment of the Coondiner Creek catchment, with Mindy Mindy Creek flowing into the Coondiner Creek downstream of Coondiner Pool. Each of these catchments includes upland source areas of the Hamersley Range (EHUs 1 and 2) in association with upland drainage floors and channel networks (EHUs 3 and 4); however the proportional contribution of these units varies considerably between the catchments . 18 Also a listed species under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 93 Our ref: FM-EcoConcept_v8.docx Upon exiting the Hamersley Range, channel flows are dissipated across the lowland plains. Drainage through these areas can be complex and consists of low-energy channels, channel breakouts and depressions. Areas of sheetflow may also occur as dictated by surface types and gradients. Within the lowland sandplains, drainage is poorly organised and infiltration rates are high. Along the fringes of the marsh, the calcrete plains (EHU 7) have numerous localised drainage termini which can collect runoff, in addition to drainages extending into the Marsh. One of the most significant features to the south of the Marsh is t he Weeli Wolli alluvial fan (Map 4-01). The distribution of flow between the channels within the alluvial fan area varies with the intensity of the event. For example, during low flow events, flow will be confined exclusively to the main Weeli Wolli Creek channel; whereas, during large events the flow within the main channel would only represent a small proportion of the total flow across the alluvial fan. Surface water runoff from the Mindy Mindy / Coondiner Creek sub-catchment, with an area of 3,205 km 2 , flows in a north-easterly direction from the Hamersley Range into the Fortescue Valley. Coondiner Creek flows through Eagle Rock Pool and Eagle Rock Falls in the upper reaches of the catchment, and Coondiner Pool at the base of the creek system (Map 3-01). Coondiner Pool occupies an area of approximately 0.09 km² and is classified as a shallow, semi-permanent claypan area/wetland. It is underlain by low permeability, fine to medium-grained alluvium. The Wanna Munna sub-catchment lies to the southwest of Coondiner Creek sub-catchment, outside the study area. It is a relatively small catchment with an area of 502 km 2 and is bound by the Fortescue River, Weeli Wolli Creek and Coondiner Creek sub-catchments. The Wanna Munna sub-catchment is believed to respond primarily as an internally draining catchment during minor and average rainfall events. However, following significant rainfall events the internal capacity of this catchment may be exceeded with flows spilling over into Coondiner Creek. It is not known whether there is any significant groundwater outflow from the Wanna Munna area into the study area. Catchments contributing to northern fringes of the Fortescue Marsh Drainage from the Chichester Range flows towards the Marsh via a series of floodplains, all uvial fans and incised ephemeral creeks. These drainage features extend along the northern edge of the Marsh, between 5 and 10 km from the base of the Chichester Range and sloping at around 0.3%. Catchments lying to the north of the Marsh include the BHP Billiton Iron Ore Roy Hill East, Goman/ Sandy Creek, Christmas Creek, Kulbee Creek and Kulkinbah Creek c atchments (Map 4-01). These catchments include a relatively even distribution of upland source areas (EHU 1 and 2 within the Chichester Range) and lowland alluvial plains (EHU 6). The upland areas drain into a series of relatively well-defined, parallel drainage channels. Moving further south, the topography becomes flat and the drainages become narrower and more divergent. A number of drainages penetrate into the Marsh, where they further distribute into splay channels and marsh playas. Areas of sheetflow may occur in the interdrainage zones. In comparison with the catchments located on the southern fringes of the marsh, flow distances from the upland to lowland areas on the northern fringes of the Marsh are shorter and cross a narrower alluvial plain. In some locations the drainages from these northern catchments feed into semi -permanent waterbodies on the fringes of the Marsh, possibly associated with channel remnants and scours. These waterbodies are referred to as Yintas and have cultural significance to Traditional Owners. Fortescue Marsh Basin The Marsh (EHU 9) is the terminus for all surrounding catchments. Runoff from the surrounding catchments is influenced by surface detention, vegetation uptake, seepage and other removal processes before reaching the Marsh basin. Examination of the 5 m DEM suggests that flood waters can pond up to 8 m in depth in the lowest elevation portions of the marsh following significant flood events. Water stored in the Marsh will slowly dissipate via seepage and evaporation. As these dissipation processes progress, the extent of the Marsh waterbody decreases and separates into a series of pools as controlled by basin topography until the surface completely dries. During the evaporation process, surface water salinity increases and traces of precipitated salt can be seen as floodwaters recede. During the seepage process, a proportion of the increasingly saline waterbody percolates into the deep, valley floor alluvium. Based on comparison between Landsat and surface topographic data, flood peak elevations of up to 407 m AHD have occurred in the Marsh area in the past several decades. Spillover from the Marsh Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 94 Our ref: FM-EcoConcept_v8.docx beyond the Goodiadarrie Hills requires Marsh flood elevations in excess of 412 m AHD, suggesting that this is a very rare event under the prevailing climate regime. Examination of the 5 m DEM, together with aerial photographs, shows that the Marsh can be partitioned into two internal catchment areas (Figure 4-7). These eastern and western basins interconnect during and following large flood events and wet periods, but may remain disconnected with lower inflows. The eastern basin is likely to spillover into the western basin at a level of around 406 m AHD. While the east- west divide is evident from the 5 m DEM and satellite imagery of flood inundation areas, field investigation and groundtruthing would be required to understand the process and explaination for formation of the divide. Satellite imagery of the Marsh (Figure 4-7 top frame) clearly illustrates this east-west divide, showing inundation of the eastern basin whilst the western basin remains dry. This situation was likely due to inflow from the upper Fortescue River catchment, following a localised rainfall event. The bottom frame in Figure 4-7 shows the Marsh basin elevations based on the 5 m DEM, with lower elevations to the east of the divide. Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 95 Our ref: FM-EcoConcept_v8.docx Figure 4-7: Fortescue Marsh internal catchment delineation as indicated by: inundulation of the west catchment only in early 2012 (Top) and by elevation differences between the east and west basins (Bottom) Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 96 Our ref: FM-EcoConcept_v8.docx 4.2.5 Flood regime Surface water expression is intermittent across the majority of the Marsh. Flooding of the Marsh corresponds with episodic surface flow events. Little data are available to quantify the flood regime of the Marsh. Flooding of the Marsh results from direct rainfall, runoff from the surrounding catchments and inflow from the Upper Fortescue River and Weeli Wolli Creek. Large surface water inflows to the Marsh are generally associated with large-scale cyclonic events in the summer months, with a mean recurrence interval of about five to seven years (DEC 2009). Historical flooding patterns of the Marsh can be inferred from Landsat imagery. The combination of Landsat imagery and high resolution DEM information can be used to improve the estimates of flooding depths and extents. A baseline flooding history dataset has been generated by UWA PhD candidate Alex Rouillard based on a review of historic Landsat images, but is yet to be published. This data would be useful to validate outputs from the conceptual water balance model (Section 4.2.6), which suggested a maximum (simulated) flooding extent of just more than 50% of the total Marsh area, and occurred only once over a 27 year simulation period (further detail provided in Section 4.2.7). Rainfall measured at the BOM Wittenoom rainfall gauge (BOM station number 5026) shows a largely drying cycle (Figure 4-8) for most of the period from 1950 to the mid 1990s. This period is followed by a wet period to the early 2000s, with clear indications of a drying period since 2001/02. A conceptual depiction of the dynamics of flooding and drying scenarios observed in the Marsh over the past three decades is shown in Figure 4-8. During the drought period from 1980 to around 1993, surface water inflows to the Marsh were well below the longe term average, with low volumes of water captured in the Marsh resulting in the Marsh being dry for extended periods. The Marsh acts as a groundwater sink although the net groundwater contribution to the Marsh is minimal, owing to the removal of shallow groundwater by evapotranspiration. A much wetter period followed between 1999 and 2002, with a number of cyclones resulting in high inflows into the Marsh and extended periods of ponding. This wetter phase facilitated groundwater recharge and rise of the watertable. The nature of groundwater flow during mounding events is still radial with respect to the Marsh basin, however the flow directions may be reversed (i.e. away from the Marsh) for short periods until the groundwater system re-equilibrates. The current period (post 2002) has seen a reduction in rainfall and runoff into the Marsh. The reduction in inflows and ponding events has contributed to a general drying trend compared to the 1999 to 2002 wet period. Outputs from the Marsh conceptual water balance model (Fig ure 4.13 and Figure 4.14) support the contention that the Marsh experiences long term (interannual to decadal) drying and wetting cycles in response to climatic conditions. Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 97 Our ref: FM-EcoConcept_v8.docx Figure 4-8: Conceptual flooding and drying dynamics of the Fortescue Marsh groundwater with rainfall cumulative deviation plot (BOM Wittenoom gauge) Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 98 Our ref: FM-EcoConcept_v8.docx 4.2.6 Hydrogeological setting As detailed in Section 2, the Fortescue Valley is underlain by a flat-lying, complex sequence of Quaternary and Tertiary alluvial, colluvial and lacustrine sediments. The saturated thickness of sediments beneath the Marsh which overlie sedimentary rocks of the Wittenoom Formation is on average 40 m (can be deeper, up to 70 m bgl, at places). Hydrostratigraphy The M arsh’s aquifer system (Figure 4-9) is associated with the following general hydrostratigraphic sequence: Alluvial and colluvial deposits, consisting mainly of fine grained material but with occasional courser grained components such as those associated with outwash fans. The permeability of the alluvium is reported to be in the order of 0.1 to 1 m /day, with coarser material exhibiting higher permeability (FMG 2005a). The alluvium is the product of complex formation proce sses and is likely to be highly variable physically and with respect to its hydraulic properties. In places the Marsh bed includes shallow hardpans with very low permeability. Tertiary Detritals (TD3 unit). A mix of complex lacustrine deposits, with textural variations from sandy silt to a silty clay, generally texturally finest at the Marsh, with very low permeability (less than 0.1 to 0.01 m/day), effectively an aquitard. Pisolitic gravel may be present in places at the base of the TD3 unit forming localised aquifers. Calcrete layers associated with ancient watertable levels. Although referred to as calcrete this unit may contain significant silcrete and ferricrete horizons as the new drilling work undertaken in 2013 and 2014 by UWA shows that this unit underwent further significant silicification or iron enrichment at places. In the Mount Lewin area, the hydraulic conductivity of the calcrete unit has been determined to be in the range of 3 m/day to 20 m/day, with an average of approximately 10 m/day (Aquaterra, 2005c). The permeability of the calcrete in the area north of the Marsh is significantly higher, FMG (2010) reporting values over 100 m/day. There may be other calcretisation horizons within the Fortescue Valley, as it is not clear whether the calcr ete outcrops to the south of the Fortescue Marsh belong to Oakover Formation. The recent UWA work confirms that in parts of the Marsh, particularly along the southern perimeter of the Marsh and further south of that perimeter, outcropping calcrete extends to a depth of approximately 16 to 25 m bgl. Calcrete is an important part of the regional aquifer under the Fortescue Marsh. Brecciated siliceous caprock has also been identified as a potential aquifer within the alluvial/colluvial deposits in the Fortescue Valley area (MWH 2009). On the northern flanks of the Marsh, the mineralised Marra Mamba Formation (a member of the Hamersley Group) dips and intersects the alluvium and Wittenoom Formation. The permeability of the Marra Mamba Formation is reported to be in the order of 3 m/day (Aquaterra 2005c). The Wittenoom Formation dolomite at depth under the Marsh. Weathered sections of the Wittenoom dolomite tend to have relatively high transmissivities (in the order of 20 m /day or more) due to the karstification (MWH 2009). Beneath the Marsh the aquifer system hosts saline to hypersaline (in the order of TDS 10,000 to 75,000 mg/L) water and the deeper aquifers are saturated with hypersaline water (in the order of TDS 75,000 to 160,000 mg/L) (FMG 2005a; FMG 2009a). The hypersalinity is a consequence of the downward density- driven migration of salt due to the increased density of the solution. Ecohydrological Conceptualisation of the Fortescue Marsh Region Status: Final September 2015 Project No.: 83501069 Page 99 Our ref: FM-EcoConcept_v8.docx Kataloq: media media -> Uşağın fərdi psixoloji hazırlığı 20 azn ağız boşluğunun kompleks peşəkar gigiyenası 80 azn media -> Tibb xidmətinin adı media -> Әrin cәmi vә hәr bir kateqoriya üzrә mәblәği vә kredit portfelindә xüsusi çәki media -> Qeyri-standart kreditlәrin cәmi vә hәr bir kateqoriya üzrә mәblәği vә kredit portfelindә xüsusi çәkisi media -> Ramiz ƏSKƏr türk xalqlari əDƏBİyyati oçerkləRİ-1 Bakı – 2011 media -> AZƏrbaycan miLLİ elmlər akademiyasi folklor institutu qarabağ: folklor da bir tariXDİr V kitab Yüklə 12,45 Mb. Dostları ilə paylaş:
|