Concerns Arise Over Flooding in Selwyn District
There is growing concern that the development of subdivisions is exacerbating flooding issues in parts of the Selwyn district. As more land is converted from open farmland to roads and residential areas, the drainage networks in the district are facing increased pressure.
Recently, Selwyn was placed under a state of emergency after experiencing two months’ worth of rainfall in just 48 hours. This extreme weather event caused severe flooding in areas such as Tai Tapu, Ladbrooks, and Doyleston.
Springs Ward Selwyn district councillor Grant Miller warned that such events may become the new normal. While developers have focused on building subdivisions with adequate stormwater plans, the capacity of the drainage systems to handle increased water flows into the rivers has been overlooked.
Two key waterways, the L II River and the Halswell River, have been particularly affected by the rapid growth of areas like Halswell and Lincoln since the earthquakes. The increase in impermeable surfaces due to housing developments has disrupted natural drainage patterns, leading to more water flowing through the drainage networks.
Efforts are being made to improve water management, with plans to investigate additional storage in the upper Halswell catchment. However, challenges remain in managing the overall volume of water in the drainage network.
Despite these efforts, concerns have been raised about the maintenance of drainage systems by landowners, especially as traditional farmers are being replaced by lifestyle block owners who may not prioritize drainage upkeep.
The management of Te Waihora/Lake Ellesmere during flooding events has also come under scrutiny, with discussions ongoing about the timing of lake openings to mitigate flood risks.
Impact of the Storm
According to Selwyn District Council Civil Defence manager Al Lawn, the recent storm lingered longer than expected, causing significant flooding in areas like Tai Tapu, Ladbrooks, and Doyleston. Post-storm assessments revealed that most buildings were safe, with only a few requiring temporary restrictions.
