Why did CSIRO undertake an assessment on Norfolk?
Since the 1970s there has been a notable reduction in rainfall over Norfolk Island. This has been most obvious during spring where 23 of the last 25 years (prior to 2019) have seen rainfall below the long-term mean. Climate models project that Norfolk Island's winter and spring will continue to be drier in the future. Norfolk Islanders have endured numerous dry periods in the past but there is now strong evidence that the frequency and severity of dry periods have been and will continue to increase. Annual and seasonal temperatures for Norfolk Island are also projected to increase into the future. Seemingly small long term reductions in rainfall can result in large reductions in groundwater recharge and runoff.
In southern Australia similar have resulted in significant challenges to water management authorities, in many cases requiring upgrades to water storage and supply infrastructure in order to reliably meet current and future projected demands.
While the impact of water stress can be wide and far reaching, the consequences of completely running out of water could be catastrophic in a community as remote as Norfolk Island. By arming ourselves with knowledge it is possible to better manage risk and minimise harmful future impacts.
The information provided by this assessment can be used to help inform the Norfolk Island community. Norfolk Island Regional Council and Emergency Management Norfolk Island make decisions on how to further their resilience under a changing climate and projected extended dry spells, and how the Australian Government can best support these efforts.
Importantly, CSIRO provides scientific input but does not advocate for a particular approach. Nor does CSIRO seek to replace any planning processes, or recommended changes to existing plans or processes, or put any pressure on residents to monitor and manage their own water stores.
On-going measurements and further studies
Following the completion of the Norfolk Island Water Resource Assessment in 2020 the Department of Infrastructure, Transport, Regional Development, Communications and the Arts commissioned CSIRO to extend their baseline hydrological monitoring on Norfolk Island. This work is currently on-going.
In response to interest and concerns from the Norfolk Island Water Resource Assessment steering committee, in 2021 the Department also commissioned CSIRO to undertake an assessment of the potential for Norfolk Island Pine trees to intercept cloud water and asked that CSIRO extend their woody weed mapping on the island. These two studies were completed in June 2023.
Assessment aims
CSIRO’s assessment builds upon the responses provided to the recent questionnaire circulated by the Norfolk Island Regional Council, existing studies and local knowledge to provide a contemporary understanding of the water resources of Norfolk Island and the opportunities to increase water security. As part of this assessment, CSIRO undertook a program of data collection and field measurements. These included measurements of water infiltrating into the soil, surface runoff, groundwater storage and water use by vegetation and a selection of households. A lack of hydrological data on Norfolk Island meant anecdotal information and records, such as bore drilling logs, held by members of the community were vital to the success of the project.
Assessment deliverables
The assessment aimed to:
- implement a hydrological measurement and monitoring program on Norfolk Island
- enhance the capacity of the community and Council to manage their water resources
- provide information to help the Emergency Management Norfolk Island committee appropriately respond to the risk of a water emergency
- undertake a prefeasibility analysis to assess water source and storage options for increasing the resilience of existing water supplies and the potential for providing redundancy in supply.