Flood 'moves mountains' of sediment

Landcare Research scientists have calculated the huge amounts of sediment shifted by the Manawatu River during the February floods

* and have advice on how to help reduce erosion caused by storms. Horizons Regional Council records for the February 16 flood show that the Manawatu River peaked at just over 8.9 metres

* a level second only to the flood of 1902 (www.horizons.govt.nz).

The floodwaters moved huge amounts of sediment, leaving widespread and serious damage. Roads were blocked, bridges washed out, and silt and sand dumped onto farmland, all resulting in significant losses to the local economy.

Landcare Research scientists Dr Roger Parfitt and Dr Troy Baisden stationed themselves on Palmerston North's Fitzherbert Bridge during the flood, lowering sampling devices into the river at regular intervals, as trees, hay bales and even cows floated by. They analysed the sediment