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Goulburn Broken Catchment Management Strategy

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Climate change strategies and plans

5. Impact of Climate Change on the Catchment’s Natural Resources

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The combination of exposure and sensitivity to climate change reflects the potential impact of climate change on the Goulburn Broken Catchment’s natural resources (as per figure 4). See figure 5, 6 and 7 below for results of the impact assessment. The criteria used for the impact assessment are outlined below in table 4 (exposure) and table 5 (sensitivity).

Figure 4: Climate change impact assessment framework (adapted from Schröter undated by Clifton and Pelikan 2014).

Table 4: Exposure assessment criteria with rationale (Clifton and Pelikan 2014)

WEIGHTING EXPOSURE CRITERION CRITERION RATIONALE
1 Maximum temperature: change in annual average Temperature influences landscape processes that are important to all natural resource classes and social-ecological systems. Maximum temperatures influence processes including water balance, fire and senescence in some winter-growing agricultural species. The annual average rather than the seasonal average was selected due to it being able to broadly represent the suite of climate changerelated temperature impacts across a year.
2 Average rainfall: Change in average spring rainfall Rainfall is a critical influence on landscape processes across natural resource classes and social-ecological systems and is a key expression of exposure to climate change. River flows and farming systems, particularly, were considered to be much more sensitive to changes in autumn and/or spring rainfall than changes in annual average rainfall. Climate change is also projected to lead to changes in seasonal distribution of rainfall, with more change during winter and spring than at other times of year.
3 Average rainfall: Change in average autumn rainfall
3 Surface water yields: change in mean annual flow Mean annual flow integrates impacts of changes in rainfall regime (amount, seasonality and variability), as well as temperature and potential evaporation. It is a key expression of exposure to climate change for water resources (including irrigation farming and towns). Change in mean annual flow is more relevant to agricultural water uses in irrigation regions than for other irrigation users and the environment. However, it is the only readily available data set that incorporates climate change projections.
4 Waterlogging and salinity: current shallow aquifer depth to water table Shallow aquifer depth to water table is a key pressure for natural resources in the Shepparton Irrigation Region and to a lesser extent in other irrigation areas and parts of the dryland. Shallow water tables are also important in sustaining groundwater-dependent ecosystems, which may be important drought refuges for native fauna.

Note: Only current conditions can be used as there is no other consistent data set available for the whole of the Goulburn Broken Catchment.

5 Flooding: area currently inundated in 1 per cent annual exceedance probability event Flooding is a critical influence on ecological processes in rivers, wetlands and floodplains and also poses an important climate-related hazard for built infrastructure and some land uses. The current 1 per cent annual exceedance probability event is a good guide to flood extent under climate change, although it is likely that floods in the current 1 per cent annual exceedance probability area may increase in frequency. Recent flood studies have not necessarily considered climate change and hence only current flood extent can be considered consistently across the region.
5 Minimum temperature: change in annual average Temperature influences landscape processes that are important to all natural resource classes and SESs. Minimum temperatures influence, for example, snow incidence and persistence and flowering patterns in agricultural and native
species. The annual average rather than the seasonal average was selected due to it being able to broadly represent the suite of climate change-related temperature impacts across a year.

Table 5: Sensitivity assessment criteria with rationale (Clifton and Pelikan 2014)

WEIGHTING EXPOSURE CRITERION CRITERION RATIONALE
1 Habitat condition: native vegetation fragmentation or connectivity The condition of native vegetation, particularly in terms of the level of fragmentation and disturbance, and its connectivity to large, contiguous areas is considered to strongly influence its vulnerability to a variety of pressures, including those arising from, or exacerbated by, climate change. These are critical sensitivity issues for terrestrial biodiversity and riparian and wetland vegetation.
1 Habitat condition: native vegetation condition
2 River health: index of stream condition streamside zone This is a measure of the condition of riparian vegetation and hence a key indicator of river health and the sensitivity of rivers to various pressures, including climate change. As this criterion incorporates vegetation condition and connectivity, it partly duplicates the habitat condition criteria.
3 Rarity: native vegetation range under current conditions Ecological vegetation class bioregional conservation status was the data set used to represent this criterion, highlighting ecological vegetation classes that have a restricted distribution. These are considered to be vulnerable to climate change because:
  • they have a naturally small range and may therefore be adapted to quite specific climatic conditions that may no longer exist at their current locations as a result of climate change.
  • clearing and other disturbances have modified their natural range and hence they are likely to be subject to a variety of other environmental pressures and hence most likely less resilient to climate change.
3 Land use: current land use Land use was classified according to sensitivity to various impacts of climate change. Data illustrates the variable nature of sensitivity to climate change.
3 Land and soil health hazards Several topography and landform criteria have been included in this criterion, such as slope and susceptibility to various soil health hazards (e.g. acidity, salinity, erosion). This highlights sensitivity to climate change from a land and soil health perspective.
4 Wetland health: proximity to wetlands The intention was to incorporate a measure of the hydrologic regime experienced by wetlands and hence their health from index of wetland condition datasets. However, there is insufficient data to represent the criterion across the Catchment. Proximity to wetlands is used as a surrogate, on the basis that wetlands are sensitive locations due to their dependence on strongly climateinfluenced factors such as river flows and/or water tables.

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Figure 5: Impact of climate change on the Goulburn Broken Catchment’s natural resources in scenario 2030. Figure 6: Impact of climate change on the Goulburn Broken Catchment’s natural resources in scenario 2050. Figure 7: Impact of climate change on the Goulburn Broken Catchment’s natural resources in scenario 2070.

Maps showing the exposure and sensitivity assessment results independently can be found in Appendix B and C respectively.

Please note: These maps are not intended to incorporate all decision-making elements but represent an assessment of climate change impact based on spatially-enabled criteria for exposure and sensitivity as part of a climate change vulnerability assessment. Vulnerability is used to highlight locations and issues to focus further analysis, including risk assessment and management. These maps should be considered in conjunction with the Climate Change Adaptation Plan for Natural Resource Management in the Goulburn Broken Catchment, Victoria, 2016 in its entirety.

  1. Has the most appropriate information been used for the impacts assessment? If not, why? Please provide details of other information.
  2. Is the presentation of spatial data (i.e. the maps) easy to interpret? If not, why? How can this be improved?