Rissington Bridge destroyed in flood. Video / Supplied
Horowhenua may have largely escaped Cyclone Gabrielle, but its effects are still being felt here: not in the least in the Manawatū River, which has its origins in Hawke’s Bay.
The opening of the Moutoa floodgates on Tuesday night has led to the spillway filling up with murky, brown water. Near the estuary, the river speeds by at a considerable clip and is as brown as coffee or tea with milk.
Debris covers much of the mudflats in the Manawatū River Estuary after Cyclone Gabrielle.
On its way down through the Tararuas it has deposited tonnes of tree limbs - from the branches of sizeable trees to stumps to whole trees and shrubs - along the foreshore and on to the mudflats of the river’s estuary, the primary feeding ground for migratory wading birds. The devastation is clear for all to see and has upset members of the Manawatū Estuary Trust.
Trust chairman Kelvin Lane said the estuary is a Ramsar site and an internationally recognised home to migratory birds, many of whom do not have webbed feet.
“They are waders, and stand on the mudflats in a little bit of water. In the next few weeks, they must fatten up to be ready for the big trek back to Alaska, or they won’t be able to go.”
Much of those mudflats are now covered with debris, severely limiting the feeding options for the birds.
Debris in the Manawatū River Estuary after Cyclone Gabrielle.
Debris can also be seen further upstream and even floating in the water at the mouth of the river. The boat ramp of the Marine Boating Club has collected substantial amounts of timber, also.
Lane blames the ongoing riparian planting farmers are required to do to protect banks of rivers and streams as the main culprit for all the debris that has washed down the river, though much of the debris appears to have come from larger trees, given the size of the branches or stumps.
“It is very clearly not forestry timber. Much of it looks like it has been taken down or has fallen off a long time ago and been left strewn on the banks, or the current storm has ripped trees out of the ground and washed them away.
“It does not make sense to cover banks in planting. We should change that and let the water do what it does. Right now, floodwaters are eroding banks and carrying the plantings with them.”
He is sure much of the timber on the mudflats comes from exotic trees, such as willows.
“They are not native trees. They have been uprooted or cut down previously and left on or near the bank. We have never seen this much debris in the estuary.”
Horizons Regional Council said that it’s pretty normal following an event of this scale to have so much debris in the estuary. The estuary is at the bottom of the catchment, so that debris has collated over a large area and come down. It’s also important to note that this event involved gale-force winds, which saw branches and trees make their way into rivers and streams.
Horizons said it’s unlikely that the debris is made up of riparian plants.
“Riparian planting [involves] natives, and [they are] on the smaller side. It’s possible that they get swept up during a flood - however, they would be a minimal portion of debris that’s at the bottom of the catchment.”
Image 1 of 10: Debris in the Manawatu River Estuary after Cyclone Gabrielle
