No.28 2008

Will we have enough water for farm irrigation by 2040?
Farm irrigation in Canterbury. (Photo: MS Srinivasan, NIWA)
The potential effect of climate change on river flows and future water supply for farm irrigation in Canterbury has been under scrutiny by NIWA scientists.
Using a river flow simulation model and focusing on the Rangitata catchment, we have been able to compare river flow under the current climate against a future climate scenario projected for 2040.

International medal for NIWA's work on irrigation schemes
Ned Norton with his award. (Photo: Nelson Boustead, NIWA)
NIWA scientist Ned Norton has won an international award for his work on the environmental impacts of irrigation schemes.

Water resources outlook (September–November 2008)
Northern North Island
Normal or below normal soil moisture levels and river flows are likely.
Southwestern and southeastern North Island
Normal soil moisture levels and river flows are likely.
Northern and eastern South Island
Normal soil moisture levels and river flows are likely.
Southwestern South Island
Below normal soil moisture levels and river flows are likely.

Studies assist in restoring Lake Ellesmere
Dr Don Jellyman measuring a 1.45 m migrating female longfin eel at Te Waihora (Lake Ellesmere). (Photo: Greg Kelly, NIWA)
 
The ecosystem of Te Waihora (Lake Ellesmere) is threatened by past human activity on the Canterbury plains, which has resulted in a high accumulation of nutrients in the water, and, combined with low lake levels, problems with algal blooms.

Water resources review (June–August 2008)
River flows
June–August 2008 river flows
River flows over the last three months were above normal in the North Island and northern and eastern South island. The Southern Alps south of Arthur’s Pass were drier than normal.
[Water resources information provided by NIWA field teams, regional and district councils, and hydropower companies.]

Watercress: one step to cleaner waterways?
Extensive growth of watercress in a farm drain in the Rotorua region. (Photo: James Sukias, NIWA)
Nitrogen and phosporus runoff from farms is having a significant effect on the viability of lakes in the Rotorua district but new work by NIWA scientists may provide a solution to help the clean-up.
Watercress, which grows naturally in New Zealand, is being trialled to see if it removes nutrients from waterways.