Table 1. Sub-indices, components and measures used in the IWC (DSE 2005). IWC sub-index Key ecological component Measure Measure type Wetland catchment Wetland catchment Percentage of land in different land use intensity classes adjacent to the wetland Threat Wetland buffer Average width of the buffer Component Percentage of wetland perimeter with a buffer Component Physical form Area of the wetland Percentage reduction in wetland area Component Wetland form Percentage of wetland where activities (excavation and landforming) have resulted in a change in bathymetry Threat Hydrology Water regime Severity of change to the water regime expected from activities identified to alter the water regime Threat Water properties Macronutrients (such as nitrogen and phosphorus) Severity of nutrient enrichment Threat Electrical conductivity (salinity) Severity of change in salinity Threat Soils Soil physical properties (soil structure, texture, consistency and profile) Percentage and severity of wetland soil disturbance Impact Biota Wetland plants Wetland vegetation quality assessment based on: critical lifeforms presence of weeds indicators of altered processes vegetation structure and health Component Impact Impact Component Wetland catchment Land use change and native vegetation clearing within the wetland catchment can cause changes in the amount and timing of water supply (surface water flows and groundwater levels) and the levels of nutrients, sediments and pollutants entering the wetland, and can cause secondary salinisation and a reduction in habitat quality for wetland fauna. Native vegetation adjacent to the wetland (i.e. within the buffer) plays an important role in ameliorating these impacts. It also provides protection from disturbance for wetland fauna. Physical Form The physical form of a wetland influences flooding depth, inundation duration and mixing. It also influences biological processes. The area of the wetland determines the amount and proportion of available habitat for biota. The bathymetry (underwater topography) of a wetland is determines the types of habitats present in a wetland. The principal threats to physical form are permanent reductions in wetland area (conversion to dry land by draining, filling, reduced water input etc.) and modifications to the wetland bed (by
Table 18. Threats to wetland hydrological regime, the actions that can be undertaken to score gain and the relevant management activities that can be selected for the management plan. Threat Gain action Management activity River regulation Restore natural water regime Provide environmental water Change operation of existing regulator Install regulator Activities that change the local surface drainage patterns Restore surface flow patterns Remove any impediments to delivery of water drained from surrounding landscape Artificially manipulated water inflow or drawdown (not associated with maintaining or restoring the reference condition of the wetland) Improve management arrangements Change operation of wetland hydrology to restore natural water regime Obstruction, regulation or alteration of the connection between the wetland and its water source Restore connection between wetland and water source Remove inflow obstructions Remove by-pass inflow obstructions Change operation of existing regulator Remove existing regulator Lower inflow threshold Obstruction or regulation of natural water outlets Restore outlet flow path Removing obstructions at outlet Change operation of existing outlet regulator Remove existing outlet regulator Drainage of water from the wetland through a pipe or channel Cease drainage of water Restore natural outlet level Remove or block outlet pipe Block outlet channel Install regulator on outlet channel Change operation of existing outlet channel regulator Disposal of waste or drainage water into the wetland (not associated with maintaining or restoring the reference condition of the wetland) Stop disposal of water to wetland Cease production of waste water Reduce volume of waste water (note new waste water volume, ML) Divert water before it reaches wetland Extraction of water directly from the wetland Stop water extraction N/A Activities that permanently raise the water level (e.g. damming the wetland or constructing levees to restrict the spread of water) Lower maximum water level Remove internal levees or other internal barriers Install connecting pipe through levee or internal wetland barrier Remove or lower dam wall or sill or install outlet within dam wall
intrusion resulting in an increase in salinity from its natural state lead to increased GW height levels: Consult CMA Catchment Management Plan Implement more efficient irrigation practices: - Benchmark current irrigation practice and reduce water use (note per cent reduction and new irrigation volume) - Stop irrigation Plant native vegetation (trees or other native deep-rooted perennials) in recharge areas (usually ridges and upper slopes) Plant native vegetation (trees or other native deep rooted perennials) in discharge areas (break of slope, or where there is perched/laterally flowing groundwater) Undertake groundwater extraction (pumping) Saline water intrusion from the marine environment resulting in an increase in salinity from natural state Cease activities that lead to marine water intrusion If marine water intrusion is due to of fresh groundwater reduce groundwater extraction Close artificially created connection to marine waters Table 20. continued. Threat Gain action Management activity Saline water is unnaturally delivered to a fresh or brackish wetland Stop delivery of saline water to wetland Divert discharge of saline water away from wetland (point source) Change irrigation and/or other land use practices (diffuse source, e.g. irrigation channels, saline runoff) Fresh water is unnaturally delivered to a saline wetland Stop delivery of freshwater to wetland Divert discharge of freshwater water away from wetland (point source) Change land use practice to stop freshwater delivery to wetland (diffuse source) Soils: Improving soil condition Wetland soils provide a physical substrate for aquatic plants and habitat for benthic invertebrates and micro-organisms. They store nutrients that are important for primary production, bind toxicants such as heavy metals and provide a site for many chemical transformations and nutrient cycling. Soils have physical (soil structure, texture and consistency), chemical (redox potential, salinity, acidity, dissolved organic carbon, nutrients, trace elements) and biological (micro-organisms, invertebrates, plants) components. The IWC includes an impact measure (soil disturbance) relating to the soil physical components.
CaLP species) Shooting under appropriate permits/licenses (non CaLP species) Table 21. continued. Threat Gain action Management activity Disturbance or pugging by feral animals (for species included in CaLP Act: foxes, rabbits, hare, pigs, goats, wild dogs) Note: NO GAIN is scored for management activities involving these species. Control feral animals in the wetland (CaLP species) Monitor and control as required (CaLP species) Shooting under appropriate permits/licenses (CaLP species) Baiting Trapping Rabbit-specific control: Warren fumigation Hand collapse Removal of surface harbor Rip warrens (seek approval of Regional Implementation Manager) Ferreting Carp mumbling Exclude carp from wetland Install carp exclusion screens at inlet/s Install carp exclusion screen with trap (push or jumping trap) at inlet/s Install carp separation cage out outlet Allow natural drying of wetland Trampling by humans Exclude or manage human access in the wetland Manage pedestrian access to wetland Prevent pedestrian access to wetland Provide low impact tracks (e.g. raised boardwalks) Rehabilitate closed tracks Cultivation Cease cultivation of wetland N/A Driving vehicles on wetland Stop or manage vehicle access in the wetland Exclude vehicles from wetland Confine vehicles to defined tracks Close tracks Rehabilitate closed tracks
Obstruction, regulation or alteration of the connection between the wetland and its water source Restore connection between wetland and water source Remove inflow obstructions Remove by-pass inflow obstructions Change operation of existing regulator Remove existing regulator Lower inflow threshold Obstruction or regulation of natural water outlets Restore outlet flow path Remove obstructions at outlet Change operation of existing outlet regulator Remove existing outlet regulator Drainage of water from the wetland through a pipe or channel Cease drainage of water Restore natural outlet level Remove or block outlet pipe Block outlet channel Install regulator on outlet channel Change operation of existing outlet channel regulator Disposal of waste or drainage water into the wetland (not associated with maintaining or restoring the reference condition of the wetland) Stop disposal of water to wetland Cease production of waste water Reduce volume of waste water (note new waste water volume, ML) Divert water before it reaches wetland Extraction of water directly from the wetland Stop water extraction N/A Restore hydrology (continued). Threat Gain action Management activity Activities that permanently raise the water level (e.g. damming the wetland or constructing levees to restrict the spread of water) Lower maximum water level Remove internal levees or other internal barriers Install connecting pipe through levee or internal wetland barrier Remove or lower dam wall or sill or install outlet within dam wall Activities leading to an increase in groundwater height Cease activities that increase GW height Manage surrounding land use to decrease GW levels: Consult CMA Catchment Management Plan Implement more efficient irrigation practices: - Benchmark current irrigation practice and reduce water use (note per cent reduction and new irrigation volume)
Shooting under appropriate permits/licenses (non CaLP species) Restore Soils (continued). Threat Gain action Management activity Disturbance or pugging by feral animals (for species included in CaLP Act: foxes, rabbits, hare, pigs, goats, wild dogs) Note: NO GAIN is scored for management activities involving these species. Control feral animals in the wetland (CaLP species) Monitor and control as required (CaLP species) Shooting under appropriate permits/licenses (CaLP species) Baiting Trapping Rabbit-specific control: Warren fumigation Hand collapse Removal of surface harbor Rip warrens (seek approval of Regional Implementation Manager) Ferreting Carp mumbling Exclude carp from wetland Install carp exclusion screens at inlet/s Install carp exclusion screen with trap (push or jumping trap) at inlet/s Install carp separation cage out outlet Allow natural drying of wetland Trampling by humans Exclude or manage human access in the wetland Manage pedestrian access to wetland Prevent pedestrian access to wetland Provide low impact tracks (e.g. raised boardwalks) Rehabilitate closed tracks Cultivation Cease cultivation of wetland N/A Driving vehicles on wetland Stop or manage vehicle access in the wetland Exclude vehicles from wetland Confine vehicles to defined tracks Close tracks Rehabilitate closed tracks Weed management within wetland Gain action Management activity
Threat Degradation of wetland by weed invasion Control weeds in wetland: Ensure weed cover does not increase beyond current levels (high threat and other weeds). Monitor for any new and emerging weeds and eliminate to <1% cover. Eradicate weeds in wetland: Non-high threat weeds: weeds that are up to 25% cover - ensure cover does not increase beyond current levels, weeds with >25% cover reduce to under 25% cover. High threat weeds: Eliminate all identified high threat weeds to <1% cover. Contact field officer if weed cover increases beyond current levels Spot spray Hand pull Herbicide injection Cut and paint – apply suitable herbicide Frilling – apply suitable herbicide Drill and fill with suitable herbicide Ring bark/cut down Controlled grazing (upon written approval) Mowing/slashing Chipping Mulching Revegetation in wetland Threat Gain action Management activity Clearing or degradation of wetland vegetation Supplementary planting or natural regeneration Natural regeneration expected from surrounding vegetation Monitor establishment of natural regeneration Develop species list for supplementary planting Collect indigenous seeds and/or divided/whole plants Place order with nursery Prepare planting or direct seeding area Plant tubestock or seedlings and guard if required Undertake weed control over planting area Replace unsuccessful seedlings if required Undertake further supplementary planting Revegetation Develop species list for revegetation Collect indigenous seeds and/or divided/whole plants Place order with nursery Prepare planting or direct seeding area Plant tubestock or seedlings and guard if required Undertake weed control over planting area Replace unsuccessful seedlings if required