Web location.. www.RiverRock.co.nz /Ngaruroro/Ngaruroro-Omahu Under construction.
Ngaruroro River - Omahu
Fernhill Bridge
The river bed is well filled with shingle which very much limits the river to carry the water it was designed to handle.
As the Gabrielle flood water was not able to pass under the bridge and get away due to berm-flow trees, overgrowth and restrictions, the flood water burst through just above the bridge and flooded the settlement of Omahu and others.
Flood photo
Omahu Flooded, Fernhill Omahu bridge in R foreground, broken stopbank L foreground. Photo / Dawson Bliss
WHY ?
Our rivers are not able to run freely when in flood.!
Our rivers were unable to flow downstream due to trees and obstructions, instead they overflowed their stop banks.
It is urgent to clean up the river beds and berms before we find ourselves with a huge damage cost.
Downstream from the above photo, the width between stopbanks is 410m. Of that 186m of trees and 183m of riverbed filled with shingle. Please view the G'Earth PDFs below to see why the stop banks failed.
1...... Tree chevrons obstructed the flow, and it went over the stop bank, could go the other way as there were trees in the way.
2...... The water guided by the tree chevrons could not get away due to being blocked by more trees, soo the water spilled over the stop bank.
3...... A ramp has blocked the passage of the water, the water unable to to get past the ramp, flowed over the stop bank.
4...... The water here could not get past the ramp and trees obstructing it, so the water flowed over the stop bank.
5...... The water here was obstructed by an old ramp and trees, so the water escaped by blowing out the stop bank.
6...... An earth chevron caused over spill here as the water was also impeded by trees in the spill over area..
7...... A Ramp and a group of trees caused a spillover the stop bank here.
8...... The water got behind the trees on the Hastings side, couldn't get away and breached the stopbank in 3 places, if these spillovers were the same as the other side, the subsequent damage would have been to Hastings would have been huge.
9...... Measurements for the width of the river and berm-flow taken here, not enough clear berm-flow area caused flooding upstream.