Natural drainage channels were overwhelmed during the heavy rainfall and overland flow (moving flood waters) was seen across Muri village. The same area of beach was eroded during heavy rainfall in April.
“A holistic approach is required for the area. In fact, the whole island needs a drainage and stormwater control overhaul and Infrastructure Cook Islands (ICI) are working toward improving this area,” says an ICI spokesperson.
Very heavy rainfall experienced vthree times last year is highlighting predictions by climatologists that long-term climatic events will be characterised by less frequent but more intense rainfall events.
“We can expect the same rainfall to keep happening in the foreseeable future, therefore we have to adapt to this expectation in our development. We cannot keep filling in wetlands and lowlands, we need to build accommodation higher, harvest rooftop rainwater, and we need to invest in a drainage system but one that works to ensure reduced sedimentation to the marine environment. Simply clearing stream banks is not a good idea as this does not allow the capturing of sediments before storm water enters the lagoon.”
In remediating Nukupure beach, three organisations have plans for the area. Two activities have been planned already by the Mei Te Vai Ki Te Vai Project and the Muri Environment Care Group. The two activities are for beach replenishment and stabilisation work.
“Due to these plans, ICI has decided it would be best to save money and mined sand and wait for these two plans to be carried out. The beach erosion is not a safety hazard for anyone, it is just an eyesore at the moment. However, remedial work on the rugby field is taking place in order to allow for the sports field to be used safely,” says the spokesperson.
After the most recent erosion at Nukupure, ICI engineers are designing a measure to divert storm water away from the main rugby field area and with suitable retention measures. Better measures upstream of the area will need to be made to alleviate the pressure downstream in the long term.
Across the world, it is standard for infrastructure to be built to withstand what is termed 10 year rain events, not 100 year events.
In defining the two events, 10 year events have a 10 per cent chance of occurring in a given year whereas a 100 year event has a 1 per cent probability of occurring in a single year. To build all infrastructure to cater for a 100 year event is unaffordable and we know that Small Island Developing States such as the Cook Islands can struggle to cater even for 10 year events.
ICI asks for everyone to consider best practice when planning their developments and will be producing a development guide to provide clear directions on development under the ICI Ridge to Reef Project.
Employing best practices will be encouraged through the guide based on where development standards are heading, to ensure the best outcomes for the community.