Aquifer refill could double returns

Initial report quantifies increased economic benefits.

Initial report quantifies increased economic benefits.

Increasing the amount of cropland under irrigation could double returns for landowners. File picture

INCREASING the amount of water in the Makauri Aquifer for irrigation could more than double the economic benefits to the region compared with decreasing it, preliminary results of the Makauri Economic Project suggest.
Council water and coastal resources officer Alice Trevelyan presented the initial modelling results to a meeting of the environmental planning and regulations committee.

The economic project is to provide an understanding of the economic consequences of water availability in the Makauri Aquifer, including cutting back on actual use, the managed aquifer recharge (MAR), and surface storage options.

The Makauri Aquifer is one of Gisborne’s most economically-significant water resources, yet is thought to be declining by two centimetres a year.

It is over-allocated by about two-thirds of actual use and a reduction of 60-70 percent would be required to balance abstraction of irrigated water with natural recharge.

In a bid to reverse the decline, the MAR trial to be completed this winter will test injecting filtered water from the Waipaoa River into the aquifer.

If successful, it would increase water availability during the irrigation season on the Poverty Bay Flats.

Preliminary modelling

Preliminary modelling in the economic project looked at four scenarios based on different levels of water availability, and crops that need irrigation (high value) and those that do not (low value).

The scenarios were: maintaining status quo, decreasing irrigation by 30 percent, decreasing irrigation by 60 percent, and increasing irrigation by 30 percent.

Crops were assigned to four groups: higher value permanent crops dependent on irrigation, including kiwifruit and apples; higher value annual crops dependent on irrigation, including salad leaf, lettuce and broccoli; lower value permanent crops generally grown without irrigation, including oranges and grapes; and lower value annual crops generally grown without irrigation, including maize and sweet corn.

The models took into account the different proportions of the high and low value crops that would be grown, based on the water available.

From the status quo of a $20 million return, a 30 percent increase in irrigation would see a 43 percent increase to $28.5m, a 30 percent decrease would see a 30 percent decrease to $14m and a 60 percent decrease would see a 38 percent decrease to $12.4m.

Because of the scale of the project, the Ministry for the Environment has provided the council extra funding to broaden the report to include its effects on the entire region.

The research will review community linkages, assess input-output models, and analyse changes in gross regional product, employment, and international exports from the region and nation, based on the the four scenarios for the Makauri Aquifer.

The project due date has been extended a month to June 30. There will be workshops on the project in May.

INCREASING the amount of water in the Makauri Aquifer for irrigation could more than double the economic benefits to the region compared with decreasing it, preliminary results of the Makauri Economic Project suggest.
Council water and coastal resources officer Alice Trevelyan presented the initial modelling results to a meeting of the environmental planning and regulations committee.

The economic project is to provide an understanding of the economic consequences of water availability in the Makauri Aquifer, including cutting back on actual use, the managed aquifer recharge (MAR), and surface storage options.

The Makauri Aquifer is one of Gisborne’s most economically-significant water resources, yet is thought to be declining by two centimetres a year.

It is over-allocated by about two-thirds of actual use and a reduction of 60-70 percent would be required to balance abstraction of irrigated water with natural recharge.

In a bid to reverse the decline, the MAR trial to be completed this winter will test injecting filtered water from the Waipaoa River into the aquifer.

If successful, it would increase water availability during the irrigation season on the Poverty Bay Flats.

Preliminary modelling

Preliminary modelling in the economic project looked at four scenarios based on different levels of water availability, and crops that need irrigation (high value) and those that do not (low value).

The scenarios were: maintaining status quo, decreasing irrigation by 30 percent, decreasing irrigation by 60 percent, and increasing irrigation by 30 percent.

Crops were assigned to four groups: higher value permanent crops dependent on irrigation, including kiwifruit and apples; higher value annual crops dependent on irrigation, including salad leaf, lettuce and broccoli; lower value permanent crops generally grown without irrigation, including oranges and grapes; and lower value annual crops generally grown without irrigation, including maize and sweet corn.

The models took into account the different proportions of the high and low value crops that would be grown, based on the water available.

From the status quo of a $20 million return, a 30 percent increase in irrigation would see a 43 percent increase to $28.5m, a 30 percent decrease would see a 30 percent decrease to $14m and a 60 percent decrease would see a 38 percent decrease to $12.4m.

Because of the scale of the project, the Ministry for the Environment has provided the council extra funding to broaden the report to include its effects on the entire region.

The research will review community linkages, assess input-output models, and analyse changes in gross regional product, employment, and international exports from the region and nation, based on the the four scenarios for the Makauri Aquifer.

The project due date has been extended a month to June 30. There will be workshops on the project in May.

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