Groundwater levels varying widely across region
The latest well monitoring results by Environment Canterbury show that groundwater levels in parts of North Canterbury and deep wells in Ashburton are low to very low for the time of the year. Groundwater levels around the rest of the region are better than for the same time last year.
Although water levels have decreased slightly since last month, groundwater levels in general are still at above or average levels for April and much higher than this time last year, said ECan hydrogeologist Dr Howard Willliams.
The groundwater levels in many shallow to intermediate depth wells (up to 50 metres deep) are high and reflect the average recharge from rain over the summer, tempered by natural decline and lower than normal demand for irrigation, due to the wetter, less sunny summer than previous summers. There is only a slight decrease from the previous month in these wells.
On the other hand, deeper wells (over 50 metres in depth) have shown only a limited response to rainfall and snow recharge over the last year and are below or just below average levels. Dr Williams says that some of these deep wells more than 150 metres deep are showing groundwater levels not much higher than at this time last year, suggesting that recharge rates are unable to keep up with both natural discharge and groundwater abstraction.
According to NIWA, rainfall was generally below average levels at Kaikoura and Waimate and above average at Winchmore, Lincoln and Rangiora. Soil moisture measurements taken at Kaikoura, Lincoln, Rangiora, Winchmore, and Waimate are close to average levels for this time of year.
Dr Williams says besides regularly monitoring wells all over the region, Environment Canterbury is keeping a register of observations from members of the public about the groundwater levels in wells and flows in rivers. “It’s useful to obtain this information to add to our records. People who live next to a river for instance are in the best position to see the changes in that river.†Anybody who would like to report recent changes in their wells and rivers can phone Environment Canterbury on
0800 324 636.
Below is a summary of the state of groundwater levels in different parts of the region.
Kaikoura
Groundwater levels in monitoring wells measured in April generally are low to very low. These levels reflect the lower than average rainfall experienced in this area over the last three months.
Waipara
Groundwater levels are generally low. Some shallow and deep wells in the Omihi and Waipara area continue to display historic low groundwater levels.
Ashley-Waimakariri Plains
Groundwater levels are at or above average at most monitoring sites across the Ashley-Waimakariri Plains area.
Central Plains, including West Melton
Groundwater levels at all depths are at average to below average levels with some exhibiting a declining trend, others a weak rising trend. Some deep wells in the Inland Plains are showing groundwater levels slightly above those monitored at this time last year, although are now on the decline.
Christchurch City
Groundwater levels are generally at average or above average throughout the area for this time of year.
Rakaia-Ashburton Plains
Shallow groundwater levels across the Ashburton-Lyndhurst Scheme area have dropped away to below average levels. Deep groundwater levels in the Urrall area remain below average and below levels at this time last year. However, groundwater levels monitored in other parts of the Rakaia-Ashburton Plains groundwater system are at or above average for this time of year.
Ashburton-Rangitata Plains
Most moderate to shallow depth wells (less than 50 metres deep) display average to above average groundwater levels, with all at higher levels than at this time last year. Inland wells that are more than 50 metres deep are showing below average levels, with some near the same levels as this time last year. Deep mid plains wells in the Chertsey area are showing average to below average groundwater levels, but above where they were at this time last year. Wells in the Mayfield-Hinds area are generally displaying average groundwater levels.
Rangitata-Orari deep aquifer
Groundwater levels in the deeper aquifer have risen since March and are now at average levels for April.
Orari shallow aquifer system
Groundwater levels in most shallow wells between the Rangitata and Waihi Rivers have declined since March and are at average levels.
The most recent monitoring data is available at:
http://www.ecan.govt.nz/Our+Environment/Water/Groundwater/Groundwater+Levels/
Irrigation restrictions
Irrigation restrictions are still in place on a number of Canterbury rivers. For an updated list go the Environment Canterbury homepage and click on Irrigation restrictions, bottom right.
For more information: Environment Canterbury Hydrogeologist, Dr Howard Williams, 03 371 7175.
Although water levels have decreased slightly since last month, groundwater levels in general are still at above or average levels for April and much higher than this time last year, said ECan hydrogeologist Dr Howard Willliams.
The groundwater levels in many shallow to intermediate depth wells (up to 50 metres deep) are high and reflect the average recharge from rain over the summer, tempered by natural decline and lower than normal demand for irrigation, due to the wetter, less sunny summer than previous summers. There is only a slight decrease from the previous month in these wells.
On the other hand, deeper wells (over 50 metres in depth) have shown only a limited response to rainfall and snow recharge over the last year and are below or just below average levels. Dr Williams says that some of these deep wells more than 150 metres deep are showing groundwater levels not much higher than at this time last year, suggesting that recharge rates are unable to keep up with both natural discharge and groundwater abstraction.
According to NIWA, rainfall was generally below average levels at Kaikoura and Waimate and above average at Winchmore, Lincoln and Rangiora. Soil moisture measurements taken at Kaikoura, Lincoln, Rangiora, Winchmore, and Waimate are close to average levels for this time of year.
Dr Williams says besides regularly monitoring wells all over the region, Environment Canterbury is keeping a register of observations from members of the public about the groundwater levels in wells and flows in rivers. “It’s useful to obtain this information to add to our records. People who live next to a river for instance are in the best position to see the changes in that river.†Anybody who would like to report recent changes in their wells and rivers can phone Environment Canterbury on
0800 324 636.
Below is a summary of the state of groundwater levels in different parts of the region.
Kaikoura
Groundwater levels in monitoring wells measured in April generally are low to very low. These levels reflect the lower than average rainfall experienced in this area over the last three months.
Waipara
Groundwater levels are generally low. Some shallow and deep wells in the Omihi and Waipara area continue to display historic low groundwater levels.
Ashley-Waimakariri Plains
Groundwater levels are at or above average at most monitoring sites across the Ashley-Waimakariri Plains area.
Central Plains, including West Melton
Groundwater levels at all depths are at average to below average levels with some exhibiting a declining trend, others a weak rising trend. Some deep wells in the Inland Plains are showing groundwater levels slightly above those monitored at this time last year, although are now on the decline.
Christchurch City
Groundwater levels are generally at average or above average throughout the area for this time of year.
Rakaia-Ashburton Plains
Shallow groundwater levels across the Ashburton-Lyndhurst Scheme area have dropped away to below average levels. Deep groundwater levels in the Urrall area remain below average and below levels at this time last year. However, groundwater levels monitored in other parts of the Rakaia-Ashburton Plains groundwater system are at or above average for this time of year.
Ashburton-Rangitata Plains
Most moderate to shallow depth wells (less than 50 metres deep) display average to above average groundwater levels, with all at higher levels than at this time last year. Inland wells that are more than 50 metres deep are showing below average levels, with some near the same levels as this time last year. Deep mid plains wells in the Chertsey area are showing average to below average groundwater levels, but above where they were at this time last year. Wells in the Mayfield-Hinds area are generally displaying average groundwater levels.
Rangitata-Orari deep aquifer
Groundwater levels in the deeper aquifer have risen since March and are now at average levels for April.
Orari shallow aquifer system
Groundwater levels in most shallow wells between the Rangitata and Waihi Rivers have declined since March and are at average levels.
The most recent monitoring data is available at:
http://www.ecan.govt.nz/Our+Environment/Water/Groundwater/Groundwater+Levels/
Irrigation restrictions
Irrigation restrictions are still in place on a number of Canterbury rivers. For an updated list go the Environment Canterbury homepage and click on Irrigation restrictions, bottom right.
For more information: Environment Canterbury Hydrogeologist, Dr Howard Williams, 03 371 7175.